&EPA
United States
Environmental Protection
Agency
Office of Transportation EPA420-R-04-002
and Air Quality January 2004
Progress Report on
Clean and Efficient
Automotive Technologies
Under Development at EPA
Interim Technical Report
> Printed on Recycled Paper
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EPA420-R-04-002
January 2004
Progress Report on Clean and Efficient Automotive
Technologies Under Development at EPA
Interim Technical Report
Advanced Technology Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
NOTICE
This Technical Report does not necessarily represent final EPA decisions or positions.
It is intended to present technical analysis of issues using data that are currently available.
The purpose in the release of such reports is to facilitate an exchange of
technical information and to inform the public of these technical developments.
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Authors and Contributors
The following EPA employees were major contributors to the development of this technical
report:
Jeff Al son
Dan Barba
Jim Bryson
Mark Doorlag
David Haugen
John Kargul
Joe McDonald
Kevin Newman
Lois Platte
Mark Wolcott
Report Availability
An electronic copy of this technical report is available for downloading from EPA's website:
http://www.epa.gov/otaq/technology.htm
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 4
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Table of Contents
Abstract 6
Executive Summary 7
1. Introduction 14
2. Overview of Individual Technologies 15
3. Key Design Features for Hydraulic Hybrid Vehicle Technology Packages 27
4. Vehicle Technology Packages and Modeling Scenarios 52
5. Projection of Fuel Economy Improvement Potential 54
6. Projection of Incremental Vehicle Cost 62
7. Projection of Payback Period and Lifetime Savings 71
End Notes -References 76
Appendices 77
Appendices
Appendix A: Sensitivity Analysis with ReducedRoadload Scenarios
Appendix B: Discussion of Efficiency Benefits of and Design Options for Increasing Average
Engine Load Factor
Appendix C: Description of EPA 's Variable Displacement Engine Design
Appendix D: Description of EPA 's Variable Compression Ratio Engine Design
Appendix E: Engine Maps
Appendix F: Hydraulic Pump/Motor Maps
Appendix G: Derivation of Base Roadload Specifications
Appendix H: Detailed City/Highway Fuel Economy Results
Appendix I: FEV Report - Cost and Fuel Economy Comparison of Diesel and Gasoline
Power trains in Passenger Cars and Light Trucks
Appendix J: FEV Report - Variable Compression Ratio and Variable Displacement Engine
Cost
Appendix K: Price Factors: Price per Unit Weight by Component System
Appendix L: Incremental Cost Calculations by Technology Scenario
Appendix M: Methodology for Brake Savings
Appendix N: Calculations of Payback by Technology
Appendix O: Review by External Organizations
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 5
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Abstract
This progress report summarizes the status of several automotive powertrain technologies under
development in EPA's Clean Automotive Technology program: hydraulic hybrid drivetrains,
clean diesel engines, and variable displacement engines.
The economic projections in this progress report are based on a longer-term, high-volume
scenario where the economies of scale and relative profit for the advanced technology vehicles
approach those for high-volume conventional vehicles today. Costs will undoubtedly be higher
during a transition period when economies of scale will be much lower and there will be a series
of necessary up-front investments, but estimates of these temporary transition costs are beyond
the scope of this paper. On the other hand, costs may ultimately be lower than those projected
here for any technology that truly achieves long-term market maturity, as that type of sustained
market share would no doubt justify continued cost reduction that cannot be predicted at this
time.
Various combinations of the new technologies included in this progress report could "payback"
to the consumer in 1 to 10 years, depending on the personal vehicle type and technology
package. All of these technology packages could provide net vehicle lifetime savings for
consumers—ranging from $1000 to $3000 for most cases—as discounted operating savings over
time more than offset higher initial vehicle prices. The maximum vehicle fuel economy
improvement and lifetime savings are achieved with a clean diesel engine (with or without
variable displacement) and a full hydraulic hybrid drivetrain with engine-off strategy. A central
assumption in this analysis is that the addition of the new powertrain technologies do not change
vehicle size, acceleration, or range. As no new lightweight materials are assumed, overall
vehicle weights increased by from 30 to 250 kilograms due to the added components in the
various technology packages.
In every case, these new automotive powertrain technologies payback for an owner of a larger
personal vehicle more quickly than they do for an owner of a smaller personal vehicle. These
new technologies would payback in large sport utility vehicle (SUV) applications with 4-wheel
drive in 1-5 years and would payback in midsize car applications with 2-wheel drive in 3-10
years, based on current fuel prices.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page
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Executive Summary
This progress report primarily addresses four technology approaches with which EPA has direct
experience, due to active in-house projects under EPA's Clean Automotive Technology program:
> mild hydraulic hybrid drivetrain, with both engine-on (where the engine is always on
unless shut off) and engine-off (with engine on and engine off cycling) strategies
> full hydraulic hybrid drivetrain, with both engine-on and engine-off strategies
> clean diesel engine
> variable displacement engine
Hydraulic hybrid drivetrains have been a core focus of EPA's Clean Automotive Technology
program since the mid-1990s. EPA has cooperative research and development agreements
(CRADAs) with Eaton Corporation, Parker-Hannifin, and the Ford Motor Company. Much of
EPA's early research focused on the design of individual hydraulic hybrid components optimized
for passenger vehicle applications (i.e., smaller, lighter, and more efficient), but more recently
EPA has been working with its private sector partners to demonstrate complete hydraulic hybrid
drivetrains in specific vehicle applications. For example, EPA recently built a mild hydraulic
hybrid urban delivery vehicle that competed in the Michelin Bibendum Challenge in September
2003 and won a gold medal for fuel efficiency and a silver medal for acceleration performance.
EPA is currently building a full hydraulic series hybrid urban delivery truck that will have
further fuel economy and performance improvements.
Clean Diesel Combustion is a second core focus of EPA's in-house research and development
program. EPA has demonstrated the lowest diesel engine-out nitrogen oxide emissions levels
ever reported in the literature, and is in discussions with several private sector organizations on
potential future partnerships to further develop this technology. Since it is premature to make
cost projections for Clean Diesel Combustion, this report uses a combination of conventional
diesel engine technology along with emissions aftertreatment technology (both for particulate
matter and oxides of nitrogen emissions) as a basis for costing out clean diesel engine
technology, and as a first-order surrogate for the costs that would be associated with Clean
Diesel Combustion.
Variable displacement refers to a specific engine concept developed by EPA that divides the
engine into two separate modules, each with its own crankshaft, that allows one-half of the
engine to be shut down and the other half to be operated at a much more efficient level, during
low-load vehicle operation. EPA is currently in the process of considering a prototype engine to
further evaluate this concept.
EPA is also optimistic about the potential of electric hybrid and fuel cell vehicle technologies,
but they are not included in this progress report because they are not part of EPA's Clean
Automotive Technology research and development program. While there are some comparable
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 7
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cost analyses that exist for hybrid electric vehicles (HEV)1, EPA does not at this time have the
ability to project future HEV costs with confidence. EPA is optimistic that the consumer
payback of electric hybrid vehicles will continue to improve in the future. Honda and Toyota
currently offer three hybrid electric models in the US market and reports suggest that owners
have been pleased with the performance of these first-generation electric hybrids. Nearly every
automobile manufacturer has announced plans to bring additional electric hybrid vehicles to the
US market in the next few years which suggests that the industry believes that the economics of
electric hybrids will continue to improve. EPA is actively seeking more updated information
from automobile manufacturers on the cost and performance of electric hybrid vehicles. Fuel
cell vehicles are the subject of intense research and development within both the industry and the
federal government's FreedomCar project, but it is impossible at this time to project fuel cell
vehicle cost with certainty.
In this progress report, a total of 40 modeling scenarios are analyzed, comprising 2 personal
vehicle classes, 5 drivetrain configurations, and 4 engine packages. Two of these scenarios
represent the "baseline" cases for the two personal vehicle classes, so there are 38 non-baseline
scenarios evaluating vehicles with advanced technology packages. It should be emphasized
that, because of the large number of technology packages evaluated in this study, it was not
possible to optimize every design. The goal in this paper is to evaluate plausible designs, and it
is expected that commercialization would yield optimization for all of the technology packages.
A central assumption in this analysis is that the addition of the new powertrain technologies do
not change vehicle size, acceleration, or range. As no new lightweight materials are assumed in
this analysis, overall vehicle weights increased by from 30 to 250 kilograms due to the added
components in the various technology packages. The two personal vehicle classes, chosen to
represent the types of powertrains used in other high-volume vehicle classes as well, are:
> large SUV, 4-wheel drive (e.g., Ford Expedition, Chevrolet Suburban, Dodge Durango)
> midsize car, front wheel drive (e.g., Chevrolet Monte Carlo, Toyota Camry, Honda
Accord)
The 5 drivetrain configurations are:
> conventional transmission (the baseline)
> mild hydraulic hybrid with engine-on strategy
> mild hydraulic hybrid with engine-off strategy
> full hydraulic hybrid with engine-on strategy
> full hydraulic hybrid with engine-off strategy
The 4 engine configurations are:
> conventional gasoline engine (the baseline)
> clean diesel engine
> gasoline variable displacement engine
1 One source of information on cost of electric hybrid powertrain components is "Comparing the Benefits and
Impacts of Hybrid Electric Vehicle Options" a report published by the Electric Power Research Institute in 2001
(with contributions from a number of consulting firms, automobile companies, and governmental bodies).
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page
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> clean diesel variable displacement engine
For each of the 20 large SUV modeling scenarios, Table ES-1 projects the absolute fuel economy
level in miles per gallon, as well as the fuel economy improvement, incremental cost, cost per %
fuel economy improvement, cost payback period, and lifetime savings all compared to the
baseline 4-wheel drive (4WD) large SUV with a conventional gasoline engine and conventional
transmission.
Table ES-1: Key Projections for Large 4WD SUV Modeling Scenarios
/ . / ' '
Large Sport Utility Vehicle
(4WD)
Fuel Economy (MPG) *
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Fuel Economy Improvement (%)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
New Vehicle Cost Increase ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cost Increase / FE Improvement ($ per %)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cost Payback to Consumers) (Years)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Net Lifetime Savings to Consumers) ($)
Conventional Gasoline Engine
17.2
23.6
19.7
26.8
19.4 I 20.0
27.0 | 27.6
22.5 j 22.8
30.9 ; 31.3
20.2
27.2
22.8
23.0
32.0
24.1
31.2 ; 34.6
base
37%
15%
56%
13% | 17%
57% I 61%
31% | 33%
80% i 82%
18% 34%
59%
33%
82%
86%
40%
101%
base
$1,668
$532
$2,195
$1,321 '• $1,336
$2,983 ! $2,999
$1,822 I $1,838
$3,487 I $3,504
$552 i $575
$2,217 $2,241
$1,055 $1,084
$2,721
$2,749
base
$45
$36
$39
$100 j $81
$52 j $49
$59 i $56
$44 ! $43
$32 $17
$38 $26
$32 $27
$33 $27
base
3.6
2.3
3.5
4.9 | 4.4
4.6 i 4.5
4.2 j 4.1
4.5 . 4.5
2.0
3.2
1.2
2.5
2.1 2.0
3.3 2.9
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
base
$2,060
$1,175
$2,738
$955
$2,733
$2,067
$3,318
] $1,282
I $2,880
j $2,202
| $3,401
$2,159
$3,559
$2,975
$4,145
j $3,527
I $4,786
j $3,472
I $4,852
* Fuel economy values are laboratory values and are about 15% higher than real-world projections.
The large number of technology packages yields a broad range of projected fuel economy
improvements. The new technologies could increase the fuel economy of a typical 4WD large
SUV from 17.2 mpg to as little as 19.4 mpg (for the conventional engine with mild hydraulic
hybrid and engine-on strategy) to as much as 34.6 mpg (for the clean diesel variable
displacement engine with full hydraulic hybrid and engine-off strategy). This range reflects a
fuel economy increase of 13-101% (all fuel economy values in this report are expressed as
laboratory values, similar to the values used for CAFE compliance and are about 15% higher
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page 9
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than real world projections provided to consumers). The technologies that could yield these fuel
economy increases would add $500-3500 to the cost of a new 4WD large SUV.
The incremental cost for any particular technology package reflects both the cost of any added
components as well as the savings from any components of the conventional vehicle that can be
deleted. For example, as shown in detail in Section 6, for the package involving a conventional
gasoline engine with full hydraulic hybrid drivetrain in a 4WD large SUV, there are several
components that can be deleted from a conventional 4WD SUV (most notably the automatic
transmission and transfer case) that total approximately $2200 in supplier cost. This offsets a
major portion of the additional cost of the hydraulic drivetrain in the 4WD large SUV, and is a
major reason why the overall incremental cost is low and the consumer payback is so short for
the 4WD large SUV.
It is very important to emphasize the underlying assumptions involved in the cost projections.
The central assumption is that the cost projections are for a longer-term scenario where the
economies of scale (component production volumes on the order of one million units per year)
and relative profit for the advanced technology vehicles approach those for high-volume
conventional vehicles today. The rationale for this assumption is threefold: 1) it allows an
"apples and apples" comparison with conventional technology, 2) a valid long-term business
case is a critical parameter for justifying investment in a new technology, and 3) it is consistent
with the cost assumptions in most other technology studies. These cost projections are not
relevant to a transition period where the advanced technology is initially commercialized (and
annual component production volumes might only be in the thousands or tens of thousands).
During a transition period, there will be many relevant cost factors that will be nonexistent or
negligible in a mature market, including but not limited to: recovery of research and
development expenditures; initial investment in component manufacturing facilities, vehicle
assembly plants, and dealer and maintenance infrastructure; engineering time for vehicle design
modifications to accommodate the new technology; and higher per unit costs due to lower
economies of scale. Accordingly, the transition costs would be higher than the long-term cost
projections for the advanced technologies in this study. On the other hand, it is also a basic tenet
of automotive production that, once a technology achieves market maturity, there is
overwhelming economic incentive to continue to invest in research to continually reduce cost.
So it is also likely that the cost projections in this report underestimate the potential to reduce
cost if and when any of these advanced technologies actually achieve market maturity. The
bottom line is that the cost projections in this study are most relevant to a period 5-10 years
beyond initial commercialization when economies of scale first reach high levels.
Cost payback period to the consumer, or how many years it would take for the discounted fuel
savings (and brake savings, for hydraulic hybrid drivetrains) to offset the higher initial vehicle
cost, is the best single metric for identifying those technologies which will be most attractive to
vehicle manufacturers and new vehicle buyers alike. Table ES-1 shows that, for 4WD large
SUVs, the payback periods for the full range of new technologies analyzed in this report range
from 1.2 years for a conventional gasoline engine and a full hydraulic hybrid drivetrain with an
engine-off strategy (the consumer acceptance of the engine cycling frequency of this
configuration is unknown), to 4.9 years for a conventional gasoline engine and a mild hydraulic
hybrid drivetrain with an engine-on strategy. Most important, almost all of the twenty 4WD
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 10
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large SUV scenarios yield paybacks of 4.5 years or less. Lifetime savings is the sum of the
discounted fuel savings due to higher vehicle fuel economy and the discounted savings in brake
maintenance (only for the hydraulic hybrid powertrains due to regenerative braking) minus the
higher initial technology cost. By definition, any scenario that has payback less that the typical
14-year vehicle lifetime will also show a positive lifetime savings, and Table ES-1 shows that
owners of 4WD large SUVs with advanced technologies could reap discounted lifetime savings
up to $5000 per vehicle.
Table ES-2 projects the absolute fuel economy level, fuel economy improvement, incremental
new vehicle cost, cost per % fuel economy improvement, cost payback period, and lifetime
savings for the 20 midsize car scenarios.
Again, the large number of technology packages yields a broad range of projected fuel economy
improvements. The new technologies could increase the fuel economy of a typical midsize car
from 29 mpg to as little as 32.4 mpg (for the conventional engine with mild hydraulic hybrid and
engine-on strategy) to as much as 64.3 mpg (for the clean diesel variable displacement engine
with full hydraulic hybrid and engine-off strategy). This range reflects a fuel economy increase
of 12-122%. The technologies that could yield these fuel economy increases would add $400-
2700 to the cost of a new midsize car.
Table ES-2 shows that, for midsize cars, the payback periods for the full range of new
technologies analyzed in this report range from 2.9 years for a variable displacement engine and
a conventional transmission, to 9.6 years for a conventional gasoline engine and a mild hydraulic
hybrid drivetrain with an engine-on control strategy. All of the remaining midsize car scenarios
yield paybacks of 4-7 years. Owners of midsize cars with advanced technologies could reap
lifetime vehicle fuel savings as much as $1400 per vehicle.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 11
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Table ES-2: Key Projections for Midsize Car Modeling Scenarios
Midsize Car
(2WD)
Fuel Economy (MPG)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
/// ///y/ / 1>/ TJ
O AC" / ^^ -J"" / *^ -J"" / ^ -J"" / ^ -J""
/ ^*/^^*/ ^ / ^*
29.0
39.8
35.4
46.9
32.4 ]
48.5 !
TV., ,
57.5 I
34.1
50.2
42.0
59.3
36.0
50.0
44.1
58.7
43.5
59.9
45.4
64.3
base
37%
22%
62%
12% |
67% j
41% ;
99% i
18%
73%
45%
105%
24%
73%
52%
103%
50%
107%
57%
122%
base
$1,206
$412
$1,613
$998 I
$2,182 |
$1,373 j
$2,567 |
$1,009
$2,195
$1,386
$2,581
$1,114
$2,307
$1,493
$2,692
$1,133
$2,330
$1,525
$2,722
base
$32
$19
$26
$83 !
$32 I
$34 I
$26 j
$57
$30
$31
$25
$46
$32
$28
$26
$23
$22
$27
$22
base
6.7
2.9
6.2
9.6 |
6.9 !
6.0 !
6.7 I
6.5
6.5
6.0
6.5
6.1
7.1
6.0
7.1
4.2
6.0
5.8
6.4
base
$583
$756
$895
$70 j
$817 :
$862 !
$1,045 !
$320
$933
$982
$1,129
$525
$808
$1,101
$986
$1,381
$1,403
$1,182
$1,231
Clean Diesel Variable Displacement Engine
Fuel Economy Improvement (%)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
New Vehicle Cost Increase ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cosf Increase / FE Improvement ($ per %)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cosf Payback to Consumers) (Years)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Net Lifetime Savings to Consumers) ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
* Fuel economy values are laboratory values and are about 15% higher than real-world projections.
All of the above results in Tables ES-1 and ES-2 are for a "base roadload" case where
aerodynamic drag and tire rolling resistance are assumed to be equivalent to typical production
levels today. Appendix A gives a perspective for the same 40 vehicle technology packages for a
"reduced roadload" case where average roadload due to aerodynamic drag and tire rolling
resistance is reduced by 20 percent due to assumed future improvements in vehicle design and
tires. In general, the reduced roadload scenarios summarized in Tables A-l and A-2 of
Appendix A yield higher percentage fuel economy improvements, higher incremental vehicle
costs, lower payback periods, and higher net consumer savings relative to the base roadload
results in Tables ES-1 and ES-2.
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page 12
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Appendix O contains a second sensitivity analysis focused on the cost projections for the 32
technology packages involving hydraulic hybrid drivetrains and based on alternative cost
assumptions for hydraulic components provided by one reviewer. This sensitivity case increases
the initial cost (and reduces the lifetime savings) of various technology packages involving
hydraulic hybrid drivetrains by between $270 and $670, and increases the payback periods of
most of these technology packages by 1-2 years.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 13
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1. Introduction
The purpose of this progress report is to describe to the public the status of, and to provide a
basis for setting priorities among, various technologies under development in EPA's Clean
Automotive Technology program.
This report has six additional sections. Section 2 describes the individual automotive
technologies which are the subject of this report. Section 3 describes in some depth the key
design features associated with the hydraulic hybrid vehicle technology scenarios. Section 4
groups the individual technologies into the 40 vehicle technology scenarios which are modeled
and evaluated later in the report. Section 5 projects the fuel economy improvement potential for
the vehicle technology scenarios. Section 6 projects the likely cost increases associated with the
advanced technologies. Finally, Section 7 projects the consumer "payback" periods and
associated lifetime savings.
There is a series of appendices following the body of the report. Appendix A provides a
sensitivity analysis for the key fuel economy and economic projections in the body of the report
based on an alternative set of assumptions related to lower vehicle roadload (aerodynamic drag
and tire rolling resistance). Appendices B through N provide more detailed technical
information to support the fuel economy and economic projections made in the body of the
report.
A preliminary draft of this study was distributed to, and comments were received from, six
external organizations for their technical review. Appendix O summarizes the most important
comments received during the review process, and includes a sensitivity analysis for the cost
projections for hydraulic hybrid drivetrains based on a series of alternative cost assumptions
provided by one reviewer.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 14
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2. Overview of Individual Technologies
There are a large number of technologies now being developed and evaluated which can improve
personal vehicle fuel economy beyond that already achieved by today's "conventional" vehicles.
The National Academy of Sciences (NAS) report "Effectiveness and Impact of Corporate
Average Fuel Economy (CAFE) Standards," published in January 2002, evaluated those
"existing and emerging" technologies which it believed had the greatest likelihood of being
integrated into commercial vehicles in the next 10-15 years.1 The technologies included in the
NAS report are technologies that can generally be described as "incremental" improvements to
the conventional gasoline engine/transmission powertrain, which has been the standard
powertrain for personal vehicles in the United States for the last century.
This progress report examines several technologies which were not included in the above NAS
report, and which would tend to involve somewhat greater changes in the design of automotive
powertrains than those evaluated by NAS. This report focuses on those technologies for which
EPA has first-hand experience, because of active in-house R&D as part of EPA's Clean
Automotive Technology development program.
This report evaluates the following basic technology approaches:
> mild hydraulic hybrid drivetrain
> full hydraulic hybrid drivetrain
> clean diesel engine
> variable displacement engine
As will be discussed later, various combinations of these individual technologies can be included
in a single powertrain. The following subsections briefly describe these four individual
technologies, as well as two additional technologies also under development at EPA but which
are not as advanced in development and thus are not evaluated in detail.
2.1 Mild Hydraulic Hybrid Drivetrain
A mild hydraulic hybrid vehicle (which is also referred to as Hydraulic Launch Assist by Eaton
Corporation, Hydraulic Power Assist by Ford Motor Company, or as a parallel hydraulic hybrid
vehicle) has both a conventional vehicle powertrain (e.g., gasoline engine with conventional
transmission) and a hydraulic secondary energy storage system that captures and stores a large
fraction of the energy normally wasted in vehicle braking and uses this energy to help propel the
vehicle during the next vehicle acceleration. The primary hydraulic components are two
hydraulic accumulator vessels (a high-pressure accumulator capable of storing hydraulic fluid
compressing inert nitrogen gas and a low-pressure accumulator) and a hydraulic pump/motor
unit which both "pressurizes" the high-pressure accumulator by pumping in greater volumes of
hydraulic fluid during braking and, in the opposite direction, utilizes the high-pressure hydraulic
fluid to generate and supply additional torque to the driveshaft during acceleration.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 15
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Hydraulics have, of course, been used on a number of stationary and non-road vehicle
applications for decades. Sporadically, researchers have investigated hydraulics for on-highway
vehicle applications. General Motors investigated hydraulics some time ago, and Professors
Beachley and Fronczak led a longtime program on hydraulics for vehicle applications at the
University of Wisconsin. Several years ago, a consortium that included VOAC and FIB A
Canning, outfitted hydraulic systems on several urban buses and refuse trucks in Canada and
Japan. Currently, researchers at FEV of America and Southwest Research Institute have carried
out hydraulics research under contract to EPA, and EPA currently has cooperative research and
development agreements (CRADAs) with Ford Motor Company, Eaton Corporation, and Parker-
Hannifin. Eaton Corporation and PermoDrive are now offering commercial applications of
hydraulic retrofit systems.
Section 3 provides a detailed description of the mild hydraulic hybrid vehicle designs that will be
evaluated in subsequent sections.
Hydraulic launch assist can be viewed as an "add on" to a conventional powertrain that does not
require any fundamental changes to the way the powertrain operates. When the vehicle brakes,
the hydraulic pump/motor uses the kinetic energy of the braking event to charge hydraulic fluid
from a low-pressure accumulator into a high-pressure accumulator, increasing the pressure of the
nitrogen gas in the high-pressure accumulator up to 5000 pounds per square inch. During the
next vehicle acceleration, the hydraulic pump/motor unit uses the high-pressure hydraulic fluid
to generate torque, sending the fluid back to the low-pressure accumulator, which is transferred
to the driveshaft.
One issue with a mild hydraulic hybrid vehicle is whether the engine would ever be shut off to
save fuel in those modes where engine power is not required (e.g., idle or deceleration) or where
the hydraulic launch assist alone is able to provide sufficient power. This study will consider
both "engine-on" and "engine-off' approaches. With an engine-on strategy, the engine would
only be shut down when the driver turns the engine off, usually at the end of a trip. With an
engine-off strategy, engine operation will be shut down whenever the vehicle is not moving.
One major benefit of a hydraulic hybrid vehicle is the ability to capture a large percentage of the
energy normally lost in vehicle braking. In urban stop-and-go driving, as much as one-half of all
of the energy available at the vehicle wheels is lost in braking and a mild hydraulic design can
capture and re-use a large portion of this otherwise wasted energy. The specific fuel economy
improvement associated with a mild hydraulic hybrid vehicle is dependent upon vehicle driving
cycle, i.e., there will always be a larger improvement for those vehicles with a high amount of
stop-and-go driving. While a mild hydraulic hybrid does require the addition of several
components not on conventional powertrains, these components are made from conventional
materials, and are relatively straightforward to manufacture.
Compared to mild electric-battery hybrid systems, hydraulics have a much higher power density
(and can capture a significantly higher percentage of braking energy). The main challenges are
noise and packaging, but these engineering issues are expected to be solvable. In January 2002,
Eaton Corporation, a major automotive component supplier, stated that the system "could be
readied for commercial introduction by mid-decade." " EPA recently built a mild hydraulic
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 16
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hybrid urban delivery truck that competed in the Michelin Bibendum Challenge in September
2003 and won a gold medal for fuel efficiency and a silver medal for acceleration performance.
Hydraulic hybrid technology has perhaps the greatest commercial potential for a wide range of
medium-duty vehicles such as urban delivery trucks, but this study evaluates its potential for
sport utility vehicles and other personal vehicles as well.
2.2 Full Hydraulic Hybrid Drivetrain
A full hydraulic hybrid vehicle represents a second-generation or second-phase hydraulic hybrid
vehicle. While a first-generation mild hydraulic hybrid vehicle essentially adds on a hydraulic
energy storage system to a conventional vehicle powertrain, a full hydraulic hybrid vehicle is
designed to maximize the benefits of a hydraulic powertrain. The nature of a full hydraulic
hybrid vehicle, where there is almost an infinite number of unique designs and control systems,
makes it difficult to specify one design that is preferable to others. However, Section 3 lays out
plausible designs for the full hydraulic hybrid vehicles that will be evaluated in subsequent
sections. While the basic hydraulic components in a full hydraulic hybrid vehicle are similar to
those used in a mild hydraulic hybrid, a full hydraulic hybrid opens up several interesting
possibilities with respect to powertrain design, including for example, a greater potential for
more frequently shutting the engine off and/or operating the engine at or near its peak efficiency.
However, whether the engine would ever be shut off to save fuel, at those times where the
vehicle is not in motion or where there is sufficient hydraulic energy to power the vehicle, is also
an important design issue for a full hydraulic hybrid vehicle. As with the mild hydraulic hybrid
drivetrain discussed above, this study will consider both engine-on and engine-off approaches.
With a full hydraulic hybrid vehicle with engine-off strategy, the engine will be cycled on and
off in a manner to optimize overall vehicle efficiency. It is important to note that the consumer
acceptance of frequent engine cycling is unknown.
There are two primary efficiency benefits of a full hydraulic hybrid system. One, as with a mild
hydraulic hybrid, is the ability to capture a large percentage of the energy normally lost in
vehicle braking. Based on EPA data, a full hydraulic hybrid can capture and re-use up to 80% of
this otherwise wasted braking energy. Two, the full hydraulic hybrid design permits much
greater use of engine-off strategies and maximizes the operation of the engine at or near its peak
efficiency. A full hydraulic hybrid drivetrain also allows the possibility of downsizing the
engine (which is assumed in this study), which is relatively more important with an engine-on
strategy than with an engine-off strategy, since with the latter the engine is already operating at
or near its peak efficiency point most of the time. Compared to a mild hydraulic hybrid vehicle,
a full hydraulic hybrid will require a more sophisticated powertrain control system, but can also
allow the deletion of the traditional mechanical transmission.
EPA work on full hydraulic hybrid technology has been a primary emphasis in the Clean
Automotive Technology program since the early 1990s. EPA has proven the basic feasibility of
full hydraulic hybrids with a series of test chassis that were built and evaluated. For example,
one of the EPA full hydraulic hybrid proof-of-concept test chassis, equipped with a small state-
of-the-art diesel engine and tested at rolling resistance and aerodynamic drag values of 0.006 and
0.2 respectively, has already achieved over 80 mpg over the Federal Test Procedure on diesel
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 17
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fuel, at a 3800-pound test weight. EPA is now in the process of building a full hydraulic hybrid
urban delivery truck that will allow a fuller demonstration and evaluation of the technology.
As with mild hydraulic hybrid vehicles, two challenges for full hydraulic hybrids are noise and
packaging. A challenge more unique to the full hydraulic hybrid vehicle, with its more
sophisticated control system that will likely involve a different engine operating strategy than
with a conventional vehicle or with mild hydraulic hybrids, is making the system transparent to
the driver. However, ongoing EPA work suggests these challenges will be solvable and that full
hydraulic hybrids will be a serious competitor for future vehicles where maximizing fuel
economy improvement is a primary objective. As with mild hydraulic hybrids, the most
compelling initial application may be in medium-duty vehicles with a very high frequency of
urban stop-and-go operation, but again this analysis only considers the potential for full
hydraulic hybrids in sport utility vehicles and other personal vehicle applications. The increased
torque and torque response available from a full hydraulic hybrid, without the fuel economy
tradeoffs usually associated with high performance vehicles, may very well be the most
important early commercialization driver for full hydraulic hybrid vehicles, considering the price
premium currently paid for such enhanced performance by many consumers.
2.3 Clean Diesel Engine
Conventional diesel engines have the following characteristics: direct cylinder fuel injection
(i.e., diesel fuel is not premixed with air prior to combustion), compression ignition (combustion
is initiated by the injection of diesel fuel into the hot, compressed charge-air), little or no intake
air throttling, high air-to-fuel ratios, and high compression ratios. Compared to gasoline engines
of similar size, diesel engines typically are more costly, more durable, and more efficient. In the
US market, the relative attributes of gasoline and diesel engines have resulted in gasoline engines
capturing over 99% of the personal vehicle market (the only personal vehicles available with a
diesel engine option are the Volkswagen New Beetle, Golf and Jetta) and diesel engines
representing the entire line-haul, Class 8 over-the-road truck market. Medium-duty trucks have
seen more of a direct competition between the two engines, with the tendency in recent years for
diesel vehicles to be taking greater market share.
There has been a vigorous, ongoing debate about the environmental merits of diesel engines in
the US. By far the most obvious environmental benefit of diesel engines is the high-efficiency
characteristic. As will be discussed in more detail later in this study, all other things being equal,
today's diesel engines are projected to achieve about 37% higher fuel economy than today's
gasoline engines, which is equivalent to about a 27% savings in fuel consumption. This
projection is similar to recent statements from the industry: General Motors has reported that
diesel engines use about 30% less fuel than gasoline engines (equivalent to about 43% higher
fuel economy) and DaimlerChrysler has recently stated that its diesel-powered Liberty sport
utility vehicle, slated for introduction in the US market in late 2004, is expected to provide up to
a 30% improvement in fuel economy.1111V Even recognizing that diesel fuel contains about 16%
more energy and carbon than an equal volume of gasoline, a vehicle mile traveled with a diesel
engine that has 37% higher fuel economy should reduce vehicle energy consumption and carbon
emissions by about 15%. On a life-cycle basis, the benefit of diesel engines is likely even
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 18
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greater due to the fact that US refineries are designed to optimize gasoline production, yielding
higher per gallon energy losses for gasoline production than for diesel fuel production. There are
other environmental advantages of diesel engines as well: near-zero evaporative hydrocarbon
emissions due to the extremely low vapor pressure of diesel fuel, low cold start emissions, and
low in-use emissions deterioration.
On the other hand, diesel combustion has in the past resulted in high levels of oxides of nitrogen
(NOx) and particulate matter (PM) emissions. High levels of NOx and PM emissions are due in
part to the fact that aftertreatment solutions have been much more difficult for diesel engines
than for gasoline engines. In order to permit diesel engines to compete for even its small
(generally less than 1%) part of the personal vehicle market, in the past Congress and EPA
permitted diesel vehicles to emit higher levels of NOx and PM emissions than gasoline vehicles.
This will change as EPA's Tier 2 emission standards phase in beginning in 2004 when gasoline
and diesel vehicles are subject to the same set of emission classification bins and all gasoline and
diesel vehicles must meet an average NOx standard. EPA regulations require a huge reduction in
diesel fuel sulfur levels beginning in 2006. This will not only reduce emissions from the
millions of heavy-duty trucks and buses powered by diesel engines already on the road, but will
also facilitate the development of the next generation of clean diesel engines that may be
considered for personal vehicle applications.
There is increasing evidence that automakers will be able to design diesel vehicles that can
comply with the Tier 2 emission standards later this decade. European automobile
manufacturers have been at the forefront of recent advances in diesel engines for use in personal
vehicles due to the fact that diesel engines have as much as 50% of the new personal vehicle
market in some European countries. Today's small European diesel engines have greatly
improved performance and environmental characteristics compared to diesel engines of just a
few years ago. US and Japanese-based automobile companies are also investing in diesel engine
R&D, driven in part by the demand for diesels in Europe but also by the possibility that diesel
engines may return to the US personal vehicle market. At this time, the primary path towards
compliance with EPA's Tier 2 standards in the future involves advances in diesel emissions
control aftertreatment. There has been considerable progress with oxides of nitrogen adsorption
catalyst technology, as well as with catalyzed particulate matter trap technology with active
regeneration control to ensure regeneration even under extreme conditions. In April 2002, EPA
tested a prototype Toyota Avensis, a compact diesel car that Toyota is developing for the
European market, possibly as early as 2004.v The vehicle uses a DPNR (diesel particulate-NOx
reduction) emission aftertreatment system which includes both a particulate trap and a NOx
adsorber. This prototype met the Tier 2 bin 5 emission levels of 0.07 grams per mile NOx and
0.01 grams per mile particulate matter. While challenges remain with respect to meeting EPA
Supplementary Federal Test Procedure (SFTP) emission standards, there appear to be no
fundamental barriers to the development and introduction of advanced diesel emission control
technology like DPNR to a broad range of personal vehicle applications.
In addition to diesel vehicle and fuel regulations, under its Clean Automotive Technology R&D
program, EPA is also evaluating unique diesel engine concepts with a goal of identifying a Clean
Diesel Combustion concept that could simultaneously be extremely efficient, clean, and cost
effective. EPA first publicly discussed this work at a diesel workshop at MIT in November
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 19
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2002.V1 EPA has now demonstrated lower engine-out nitrogen oxide emissions levels than
anything reported in the literature, and this suggests the potential for a diesel engine design,
using innovative air, fuel, and combustion management and conventional particulate matter trap
aftertreatment, that might be able to achieve Tier 2 bin 5 NOx levels without the need for NOx
aftertreatment. EPA is currently in the process of discussing this technology in technical forums
with the goal of setting up a consortium of one or more interested private sector companies to
carry this research forward.
Of course, whether diesel engines will enter the US personal vehicle market will depend on more
than just environmental issues, there are also issues of consumer acceptance and cost.
Historically, diesel engines have always been more costly than gasoline engines. We will return
to this important issue in Section 6.
2.4 Variable Displacement Engine
A variable displacement engine is an engine that can be operated at multiple displacements by
varying the cumulative volume swept by the pistons. The concept of variable displacement has
received attention for many years because of its obvious potential to increase vehicle fuel
economy. In a conventional vehicle where the engine is the only source of on-board power, the
engine must be sized to accommodate the maximum power requirements for rapid acceleration,
hill climbing, and/or towing. The efficiency of an internal combustion engine is highest at
relatively high loads. Unfortunately, engine efficiency is much poorer at low and moderate
loads, and most people operate their vehicles at lower engine loads much more frequently than
they do at high engine loads (for example, maintaining a constant 70 miles per hour during
highway driving places only a moderate load on the engine). The net result is that the average
overall efficiency of a conventional gasoline engine (typically between 15% and 20%) is much
lower than its peak efficiency (typically between 30% and 35%). If the displacement of the
engine could be varied, then the engine could be operated at or near its peak efficiency much
more often, leading to a large increase in the average overall efficiency of the engine. Appendix
B has a more in depth discussion of the potential efficiency benefits available from increasing
the average engine load factor.
There has been considerable research into ways to vary engine displacement. Probably the most
well known approach is to simply shut down one or more engine cylinders, generally referred to
as cylinder deactivation. There are several ways to shut down cylinders, most based on denying
fuel and air to selected cylinders. General Motors has been a leading proponent of what they call
"Displacement-on-Demand." Its approach automatically closes both intake and exhaust valves
for half of the engine cylinders during light load operation when power demands are low.
General Motors has stated that its Displacement-on-Demand technology can boost fuel economy
by an average of about 8% and as high as 25% in certain real world driving conditions. General
Motors has announced that it will introduce Displacement-on-Demand in 2004 on over 150,000
of its Vortec V-8 engines, and that it expects to increase production of this technology to nearly
1.5 million units by 2007, including both pickup truck and sport utility vehicle applications/11
The recent NAS study included cylinder deactivation in its "production-intent" technology
scenarios, postulating a 3-6% fuel economy improvement at a cost of $112-$252 per vehicle/111
Cylinder deactivation has the primary advantage of being a relatively straightforward approach
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to variable displacement, minimizing necessary changes to conventional engine design, but has
the drawback of retaining the friction losses involved in a moving piston acting against a "gas
spring."
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Figure 2-1: EPA Variable Displacement Engine Concept
There is an alternative
approach to variable
displacement that may
well have the potential to
be a more cost effective
approach for improving
vehicle fuel economy.
One critical feature of the
EPA concept, shown in
Figure 2-1, is that it
involves two crankshafts,
one for each of the two
engine "modules." Each
engine module/crankshaft
acts as an independent
unit. The "base" engine
module would be sized to
be able to provide
sufficient power for most
vehicle operation, and
during these times the first
engine module will
generally have a relatively
high load factor and efficiency, while the second engine module does not operate at all. Because
of the independent crankshafts, when the second engine module is not operated, not only is
combustion inhibited but the pistons in the second engine module do not move either, which
means no friction losses whatsoever. This is a primary advantage of this design. During high
power needs, such as acceleration, hill climbing, and/or towing, the second engine module is
quickly started and the control system adjusts the individual power levels of the two engine
modules to optimize overall powertrain efficiency. Appendix C contains more details about
EPA's variable displacement design.
One operational challenge that must be addressed relates to rapid and seamless start-up of the
second engine module. It is important that the second engine be able to move from being off to
full power within 0.3 seconds or less. Frequent starting of the second engine module also raises
issues of driver "feel", noise, emissions and durability, so engine startup, control, and power
balancing are essential elements of this engine design.
Specific efficiency and cost projections will be made in later sections, but it appears that this
variable displacement concept has the potential to be more cost effective than cylinder
deactivation and other variable displacement concepts that have been discussed in the literature
to date.
Sections 2.1 through 2.4 describe the four technologies under development at EPA that are
evaluated in detail later in this report. Sections 2.5 and 2.6 describe two additional technologies
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which are at a more preliminary stage of development at EPA and therefore cannot be evaluated
in detail at this time.
2.5 Variable Compression Engine
A variable compression engine is an engine that can be operated at different compression ratios.
As with variable displacement, the general concept of variable compression has received
attention for many years due to its potential to increase vehicle fuel economy. In a conventional
vehicle where the engine is the only source of on-board power, the engine design is
compromised with a single compression ratio that provides acceptable combustion under all
vehicle and engine operating modes. In general, raising compression ratios higher than those
typically used in today's gasoline engines (8:1 or 9:1 with regular gasoline and 10:1 or 10.5:1
with premium gasoline) would increase engine efficiency. But, at high engine loads,
compression ratios higher than these levels generally lead to excessive peak cylinder pressures
and pre-ignition. The basic concept of a variable compression engine fueled with gasoline is that
compression ratios would be increased to, say, 13:1 or 14:1 during most vehicle and engine
operating modes, where efficiency would be increased with no negative side effects, and then
lowered during the intermittent high power modes where high compression is not desired. Such
a design could potentially yield a large increase in the average overall engine efficiency.
There has been much research into variable compression engines, with several such operating
engines. Saab has a prototype variable compression engine that appears to be one of the most
advanced concepts.1X The Saab Variable Compression (SVC) engine is a 1.6-liter, 5-cylinder
engine. The mechanism for the varying compression is "tilting" the monohead of the engine
through the use of hydraulic actuators. This is turn varies the volume of the combustion
chambers and the resulting compression ratio from 8:1 to 14:1. Saab states that its SVC engine,
without downsizing the engine, increases fuel economy by about 4%. With a smaller engine and
supercharging, the fuel economy increase can be as high as 30%. Saab has not announced any
formal commercialization plans. The NAS study included variable compression engines in its
"emerging" technology scenarios (i.e., 10-15 years), postulating a 2-6% fuel economy
improvement at a cost of $210-$490 per vehicle.x
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Figure 2-2: EPA's Variable Compression Engine Concept
EPA has developed a
variable compression engine
concept that also appears to
have promise. The EPA
concept achieves two unique
compression ratios, without
changing the overall length
of the engine cylinder or the
length of the connecting
rod/piston assembly, by
using a "pi ston-within-
piston" mechanism. Figure
2-2 shows a detailed
drawing of this "piston
within a piston." During
times of low and moderate
power demand that typify
most driving modes, the top
of the inner piston is flush
with the top of the outer piston, yielding a compression ratio higher than those used in
conventional vehicles and improving efficiency. When vehicle power demand increases to the
point where this compression ratio might lead to pre-ignition or durability concerns, a command
signal causes the inner piston to recede to the second position within the outer piston, thereby
increasing the total clearance volume and reducing the compression ratio to prevent pre-ignition
and/or durability concerns. One important feature of this design is it will require fairly simple
engine design changes. A second important feature of this design is that good fuel-air mixing
and combustion is retained under both compression modes because the piston bowl resides
within the receding inner piston and therefore the outer piston squish height (the distance
between the piston at top dead center and the cylinder head) does not change. The only change
is the distance of the piston bowl from the cylinder head. Appendix D contains a more detailed
description of the "piston within a piston" design.
As with all variable compression engine concepts, there are several challenges that remain to be
addressed. The biggest challenge with EPA's variable compression engine concept is the
reliability and durability of the inner piston mechanism.
The likely cost and efficiency of variable compression engines are unknown at this time, though
it is likely that they will be similar to those of variable displacement engines.
2.6 Homogeneous Charge, Compression Ignition Engine
In terms of fundamental combustion, a homogeneous charge, compression ignition (HCCI)
engine can be considered a hybrid between a conventional gasoline engine (which premixes the
fuel and air before combustion and uses a spark to initiate combustion) and a conventional diesel
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engine (which does not premix the fuel into the air and which uses the injection of fuel into the
hot, compressed charge-air to initiate combustion). An HCCI engine premixes the fuel and air
(like a conventional gasoline engine) and uses control of compressed charge-air temperature as
the primary means to initiate combustion (somewhat like a conventional diesel engine). HCCI
engines have the potential to be able to combust a wide variety of fuels including gasoline (high
octane and low cetane), diesel (high cetane and low octane), and many alternative fuels. The
primary challenge for HCCI engines, and the primary reason they have not been commercialized
in the past, is that the design and operational features of previous engines made it extremely
difficult to control the combustion process, particularly in terms of ignition timing and
combustion rate. But the major advances in computerized controls of the last two decades and
breakthroughs in new engines have greatly improved the potential for successful development of
HCCI engines.
The primary driving force for interest in HCCI engines has been their potential environmental
performance. Gasoline engines, particularly in combination with sophisticated three-way
catalysts, can yield extremely low criteria emissions but have relatively low overall efficiency.
Diesel engines provide much higher efficiency than gasoline engines, but have historically had
high emissions, particularly of particulate matter and oxides of nitrogen (NOx). In effect, HCCI
engines offer the best of both worlds: the potential to equal or possibly exceed diesel efficiencies
with emissions as low as or likely lower than gasoline engines. In fact, the extremely high air-
fuel ratios of HCCI engines suggest the likelihood of engine-out NOx emission levels so low that
NOx emissions aftertreatment will likely not be needed to meet Tier 2 levels, a situation that will
not be possible with either conventional gasoline or conventional diesel engines. The air-fuel
premixing minimizes the formation of parti culate matter, so parti culate traps are not needed
either. Engine-out levels of hydrocarbons and carbon monoxide are sufficiently high that
oxidation catalysts will be needed to bring these emissions down to Tier 2 levels. But, the cost
of a simple oxidation catalyst is much lower than that of today's three-way catalysts used on
conventional gasoline vehicles and much lower than the NOx adsorbers and paniculate traps that
are likely to be needed on conventional diesel engines.
HCCI engines are the subject of considerable research and development by industry,
government, and academic researchers throughout the world. To our knowledge, EPA has been
able to achieve what no other researcher has yet reported: the ability to run a 4-cylinder HCCI
engine over a broad engine map with acceptable combustion control and engine performance.
EPA has demonstrated engine operation that yields efficiencies very similar to today's best
diesel engines, NOx emissions at levels of below 0.2 grams per kilowatt-hour, and near-zero
particulate matter emissions.X1
As with any advanced engine concept, there are challenges that remain to be overcome. Like
diesel engines, HCCI engines achieve higher cylinder peak pressures than do conventional
gasoline engines, which must be addressed in engine design. HCCI engines require high boost
levels, which will require a turbocharger and/or supercharger, which raises cost and packaging
issues. And HCCI engines have high air charge cooling requirements, which will likely require
an intercooler, which raises packaging issues.
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The likely cost of HCCI engines is unknown. Relative to a conventional diesel engine, HCCI
engines have some elements that will increase costs (the need for higher boost and cooling, more
sophisticated engine control system) and some elements that will decrease costs (a relatively
inexpensive fuel injection system, a simpler emissions aftertreatment system). Similarly, precise
estimates of HCCI engine efficiency are not possible pending further research and development.
At this time, our best estimate is that the cost and efficiency of HCCI engines will be similar to
those of clean diesel engines.
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3. Key Design Features for Hydraulic Hybrid Vehicle
Technology Packages
The purpose of this section is to describe key components in a hydraulic hybrid vehicle (HHV),
demonstrate the feasibility of integrating these systems into a large sport utility vehicle (SUV)
and a midsize car, and estimate the mass increase of the hydraulic drivetrains included in this
study over conventional drivetrains. A separate section on hydraulic hybrid vehicle design
features is appropriate because hydraulic hybrid drivetrains involve a wider range of changes
than replacing one engine design with another, and because there is much less in the existing
literature on hydraulic hybrid designs. The section is organized into two parts. Subsection 3.1
describes the key individual components used in some or all of the hydraulic hybrid designs, and
Subsection 3.2 describes specific, plausible mild and full hydraulic hybrid system designs for the
SUV and midsize car scenarios.
The analysis assumes base vehicle specifications and components similar to a 1999 Ford Taurus
and a 1999 Ford Expedition. The Taurus and Expedition were chosen because previous EPA
hybrid drivetrain development programs focused on these vehicles. The rear suspension system
for the large SUV is assumed to be an independent design similar to the 2003 Ford Expedition,
rather than the live axle used in the 1999 Expedition. Table 3-1 summarizes some specifications
for the base SUV and midsize car used in the analysis.
Table 3-1: Base Conventional Vehicle Specifications
Component
Engine
Transmission
Front differential final
ratio
Rear differential final ratio
Rear suspension
Transfer case
Curb weight
Fuel Tank size
SUV
5.4L V8 gasoline
4R100 4-speed automatic
3.55
3.73
Independent
Modes: Automatic 4WD,
4WD high, 4WD low
5700 Ib.
28 gallon
Midsize Car
3.0L V6 gasoline, 2v/cyl
AX4S 4-speed
automatic
3.77
-
-
-
3350 Ib.
16 gallon
3.1 Key Components of a Hydraulic Hybrid Vehicle
The key components of a hydraulic hybrid vehicle include:
> pump/motor(s) with integral valves
> accumulators with integral valves
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> hydraulic fluid
> an oil conditioning system
> a hydraulic power steering system (for some configurations only)
> a unique battery, alternator, and starter system
> general hydraulic fittings and hoses
Each of these components is described in this subsection and form the basis for estimating the
mass of the four specific hydraulic hybrid configurations in Subsection 3.2. Component mass for
each vehicle configuration is a key input in the methodology for projecting incremental cost in
Section 6.
3.1.1 Pump/Motor with Integral Valves
Hydraulic pump/motor (P/M) units are energy conversion devices. In the pump mode, the P/M
converts kinetic energy from vehicle motion into hydraulic energy, which is stored in an
accumulator. In the motor mode, the P/M converts hydraulic energy stored in the accumulator
into vehicle kinetic energy as the vehicle accelerates. Hydraulic P/Ms are analogous in function
to electric generators and electric motors used in electric hybrid vehicles. P/M designs used in
high fluid pressure applications are typically of the bent-axis or swashplate (in-line) type. In a
bent-axis design, the pistons reciprocate on an axis that is "bent" on an angle relative to the
input/output shaft. In a swashplate unit, the pistons reciprocate on an axis that is in-line with the
input/output shaft. Bent-axis P/Ms achieve higher efficiencies than swashplate units, which
make them more attractive for high fuel economy HHV applications.
For this reason, the P/M used in this analysis is a high efficiency, variable displacement bent-axis
unit. It has an integrated flow control valve and proportional electro hydraulic displacement
actuator providing infinitely variable control between zero and maximum displacement. The P/M
is made primarily of cast iron and steel, with some bronze and aluminum components.
Manufacturing complexity for a P/M, which contains pistons, connecting rods, cylinder bores,
rotating shafts, roller and bronze bearings, and electronic components and sensors associated
with displacement and mode control, is similar to that found in automotive engines. High and
low-pressure ports with face seals connect the P/M to the accumulator through hoses and tubing.
The P/M case is designed to handle the maximum pressure from the low-pressure accumulator
(1.4 MPa or 200 psi), eliminating the need for a separate leakage recovery system.
The estimated mass of a stand-alone 110 cc/rev unit with SAE standard 4-bolt mounting flange
and splined input shaft is 37 kg, based on a unique EPA P/M design. Other size units scale
roughly proportional to displacement; therefore a 55 cc/rev unit is projected to weigh half that of
the 110 cc/rev unit (18.5 kg). The P/M was designed to handle pressures of 48.3 Mpa (7000 psi),
although all projections in Section 5 assume a maximum P/M inlet pressure of 34.5 Mpa (5000
psi) to allow for a safety margin. Since a lighter P/M could be designed for the 34.5 MPa
application analyzed in this study, the above P/M mass estimate is conservative.
Depending on application in the drivetrain (engine pump, front drive unit, etc.), the P/M mount
geometry will differ from the SAE 4-bolt mount, although the mass will be similar. Changes to
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the base mass of 37 kg due to mounting or integration with other components will be addressed
within the discussion of each hybrid configuration.
3.1.2 Accumulators with Integral Valves
Hydraulic hybrids utilize accumulators to store energy. In this way, accumulators are similar in
function to the battery pack of an electric hybrid vehicle. However, unlike batteries,
accumulators have extremely high power densities (kW/kg) and can operate over a wide range of
power at very high efficiency. On the other hand, energy density (kJ/kg) is relatively low
compared to an electric battery. Thus, accumulators are better suited for short bursts of power
rather than for sustained energy delivery. Accumulators are used to store energy from vehicle
braking, and depending on the vehicle configuration, they can be used to allow the engine to run
at a near steady-state output independent of drive power demand.
The type of hydraulic accumulators used for the HHVs in this analysis are hydro-pneumatic
accumulators — they store energy in a gas spring. The oil in a hydraulic hybrid vehicle is
essentially non-compressible, and therefore cannot store energy. Instead energy is stored in a gas
(nitrogen) that is compressed by incoming oil. A movable barrier (such as a rubber bladder,
metal-lined plastic bag, bellows, or piston) separates the oil from the gas as the accumulator fills
with oil, keeping the gas inside the accumulator and preventing it from spreading throughout the
hydraulic system. Within the gas side of the accumulator is flexible open-celled foam that
increases accumulator efficiency by reducing heat losses.
All of the hydraulic hybrid configurations in this analysis require one high-pressure and one low-
pressure accumulator. The difference in pressure between the high and low-pressure
accumulators, when connected to the inlet and outlet ports of a P/M, is transformed into shaft
torque to be used to accelerate or decelerate the vehicle or absorb engine power. Both the high
and low-pressure accumulators
have composite shells made Figure 3-1: Accumulator Components
from carbon and e-glass fiber
with an epoxy matrix. EPA
contractors have fabricated
and successfully tested several
sizes of carbon/e-glass fiber
composite accumulators. The
basic components of the
accumulators are shown in
Figure 3-1 and described
below.
Composite Wrap
Gas Volume (With Foam)
End Boss
Gil Port
Gil Volume Thermoplastic Liner Gil/Gas Separator
End Boss
Gas Fort
High-Pressure Accumulator Shell
The high-pressure accumulator shell is constructed of carbon fiber and e-glass with an epoxy
matrix. The carbon fiber provides most of the vessel's strength, while the e-glass provides
impact strength. The high-pressure accumulator could be reinforced entirely of carbon fiber (no
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e-glass) to reduce mass, but costs would likely increase. EPA chose a reasonable balance
between cost and mass for its design.
The high-pressure accumulator has a maximum service pressure of 35 MPa (5000 psi), and is
designed to have a burst pressure safety factor of 3.0 (i.e., the burst pressure is 105 MPa or
15,000 psi). The vessel is constructed with a sacrificial outer layer to provide abrasion
protection. The high-pressure accumulator has steel end bosses that are molded into the molded
thermoplastic liner with threaded bosses for insertion of the oil and gas end ports. The total mass
of a 56.8 L (15 gallon) high-pressure accumulator shell is 38.0 kg.
Reducing the safety factor with respect to a burst pressure of 2.25 could reduce the mass of the
accumulator shell. This is the same value utilized by the natural gas vehicle industry. This
would likely reduce the mass of the carbon, e-glass and epoxy by fifteen to twenty percent, for a
total shell mass of 32.6 to 34.0 kg. Additional mass could likely be removed from the end bosses
and liner in a mass production design. The vessels this data are based on were development
prototypes utilizing existing tooling when possible.
Low-Pressure Accumulator Shell
The low-pressure accumulator is used to store and contain the oil when it is not in the high-
pressure accumulator. It also provides sufficient inlet pressure to the hydraulic pumps to avoid
cavitation, a condition arising in pumps when inlet pressure falls low enough to cause bubbles to
form in the fluid. An atmospheric reservoir could be used in place of the low-pressure
accumulator, but additional charge pumps would be required to boost inlet pressures to the main
pumps. This would increase mass, complexity, and energy losses of the system.
The low-pressure accumulator is designed for a maximum service pressure of 1.4 MPa (200 psi),
and has a burst pressure safety factor of 5 (i.e., the burst pressure is 7 MPa or 1000 psi). It is
constructed of a glass fiber and epoxy matrix. The recommended safety factor with respect to
stress rupture is higher for glass fiber composite pressure vessels than for carbon fiber vessels. A
lower mass carbon/e-glass shell could be constructed at higher cost, but this was not the
approach used by EPA. The low-pressure accumulator has aluminum end bosses molded into
the thermoplastic liner that have threaded bosses to allow the insertion of oil and gas end fittings.
The total mass of a 56.8 L (15 gallon) low-pressure accumulator shell is 13.0 kg. Additional
mass could likely be removed from the end bosses and liner in a mass production design. The
vessels this data are based on were development prototypes utilizing existing tooling when
possible.
Nitrogen
Nitrogen, the gas typically used to charge hydro-pneumatic accumulators, is non-reactive and
inexpensive due to its abundance in the atmosphere. The high-pressure accumulator is pre-
charged with nitrogen to a level that both maximizes the energy storage in the accumulator and
keeps the minimum system pressure high enough to deliver the required torque from the P/Ms.
A 56.8 L (15 gallon) high-pressure accumulator is charged with 7.5 kg of nitrogen to obtain a
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pre-charge of 12.4 MPa (1800 psi). A 56.8 L (15 gallon) low-pressure accumulator is charged
with 0.3 kg of nitrogen to obtain a pre-charge of 0.5 MPa (70 psi).
Accumulator Foam
When the oil flows into the accumulator and the gas is compressed, heat is generated and
transferred to the oil and the shell of the accumulator. When the oil flows back out of the
accumulator, the nitrogen expands and cools and heat transfers back to the gas from the oil and
the shell of the accumulator. Some of this heat is irreversibly lost in the process, decreasing the
efficiency of the accumulator.
To reduce the heat loss, open-cell foam is placed inside the oil-gas separator along with the
nitrogen. The foam reduces the heat loss by providing a heat sink, and providing a large surface
area for heat transfer to occur over small differential temperatures. The foam used for the HHV
accumulators is polyurethane foam with a density of 96 kg/m3. It is reaction injection molded in
place inside the oil-gas separator using a two-component curing foam, not unlike that used in
automotive seat fabrication. A 56.8 L (15 gallon) accumulator has 5.2 kg of polyurethane foam
cast into each bag, for a total of 10.4 kg for both accumulators.
Oil-Gas Separator
The oil and gas sides of the accumulator are separated to prevent the nitrogen charge gas from
going into solution in the oil. This can result in the gas coming back out of solution when the oil
is brought to a lower pressure, turning the single-phase relatively non-compressible oil to a two-
phase mixture of gas and oil that is highly compressible. Gas bubbles in the oil can lead to
extreme cavitation wear on pump components and can also cause noise as the bubbles are
collapsed in the pump.
Conventional bladder accumulators utilize an elastomeric rubber bladder to separate the nitrogen
and oil. Bladders perform well in many respects, but nitrogen permeation rates through the
rubber material are considered too high for automotive applications where a "fill for life"
specification is highly desirable. Thus, it is assumed that an HHV will utilize a permeation-free
barrier similar to concepts currently under development at EPA. The mass of these barriers is
expected to be similar to the mass of conventional bladders, with approximately 50 percent
higher cost.
To prevent the bag from being herniated out of the accumulator oil port, an anti-extrusion valve
is necessary. It is a step valve that is depressed to seal off the accumulator to prevent further
expulsion of oil and rupture of the bag. The permeation-free barrier bag has a metal plate
bonded to the end to make contact with the anti-extrusion valve.
In order to charge the accumulator with nitrogen, a nitrogen charge valve is affixed to the end of
the oil-gas separator bag. This is a steel fitting bonded to one end of the oil-gas separator, with a
schraeder valve for filling. The nitrogen gas port has 0.5 kg of steel for the high-pressure
accumulator and 0.2 kg of aluminum for the low-pressure accumulator, for a total of 0.7 kg.
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Integral Valve
Both the high-pressure and low-pressure Fi§ure 3'2: Accumulator Integral Valve
accumulators utilize one valve that is
integrated with the fluid port (see Figure 3-2).
The valve has three main functions. The first,
as mentioned earlier, is to prevent the bladder
from herniating out the fluid port when oil is
fully drained from the accumulator. The
second is to function as a flow fuse in the
event of a catastrophic hydraulic line failure.
The valve automatically closes if the flow
rate out of the accumulator exceeds a predetermined level. Finally, the valve can function as a
leak free shut-off. When the vehicle is parked or being serviced, the valve can keep the majority
of hydraulic oil in the system trapped indefinitely. The steel high-pressure valve has a mass of
4.3 kg, and the low-pressure valve has a mass of 2.9 kg.
Table 3-2: Accumulator Component Mass Summary
Accumulator Summary
Table 3-2 presents a summary
of the component masses for
56.8 L (15 gallon) high-pressure
and 56.8 L (15 gallon) low-
pressure accumulators. The
mass of other size accumulators
required for the hybrid
configurations discussed in
Subsection 3.2 is extrapolated
from this prototype design.
3.1.3 Hydraulic Fluid
The two main criteria for
selecting an acceptable
hydraulic fluid for use in
hydraulic hybrid vehicles are 1)
high and low-temperature
performance, and 2) service life.
The fluid must provide sufficient lubrication at continuous service temperatures of 93 °C (200
°F), with extreme intermittent operating temperatures of up to 121 °C (250 °F). At the same time,
the fluid must be able to flow at -40 °C (-40 °F) without causing harmful cavitation at the pump
inlet. Viscosity breakdown and fluid oxidation must be minimal, such that oil changes will not
be necessary between 150,000-mile service intervals.
Component
Composite Shell
Carbon Fiber
E-Glass Fiber
Epoxy Matrix
Liner
End Bosses
Gas Valve
Bag
Foam
Nitrogen
Shutoff Valve
Total
Low-pressure
Accumulator
Mass (kg)
5.7
1.6
4.4
2.1
0.2
1.0
5.2
0.3
2.9
23.5
High-pressure
Accumulator
Mass (kg)
16.1
3.4
7.6
4.4
6.0
0.5
1.0
5.2
7.5
4.3
56.0
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The most cost-effective hydraulic fluids that meet these design criteria for the hydraulic system
are blends of synthetic Poly-Alfa-Olefin (PAO) or high-grade mineral oil (Group III) base
stocks. These possess a high viscosity index (i.e., their viscosity changes relatively little with
temperature), and provide long service lives without unacceptable degradation in performance.
The estimated density of this type of fluid is 0.84 kg/L.
The majority of the oil in a HHV is in the accumulators. When "full" of oil, approximately 50
percent of the interior volume of an accumulator is oil. This is done to maximize the energy
storage of the accumulator (based on the gas change-of-state equation for nitrogen) and is related
to the nitrogen pre-charge pressure chosen. Some oil is also present in the P/M cases, hydraulic
lines, valve blocks, oil cooler and filter. The oil present in these components is estimated based
on the interior dimensions of EPA prototype hardware and adjusted based on the vehicle
configurations analyzed in the following subsections.
3.1.4 Oil Conditioning System
In a hydraulic hybrid, the oil needs to be kept clean and its temperature controlled to prevent
excessive weaR&Damage to the components in the system. This is accomplished using a filter,
an air-to-oil cooler, and valves to control oil flow. The size of the filter, cooler, and valves will
vary depending on the size of the hydraulic system in the HHV. A schematic of the system is
shown in Figure 3-3.
When the front drive motor is motoring, oil Figure 3-3: Oil Conditioning System
flows from the high-pressure accumulator to
the low-pressure accumulator. At this time
low low-pressure oil is directed through a filter
and air-to-oil cooler. If the back-pressure
exceeds a predetermined level, a relief valve
opens, and flow can bypass the filter and
cooler. If the oil temperature is low, a
thermostatic valve opens to bypass the cooler.
When the drive motor is pumping, oil flows
from the low-pressure accumulator to the high-
pressure accumulator. Oil is prevented from
back-flushing the filter by a check valve and is
instead directed around the filter and cooler. This redirection of flow also minimizes the
pressure drop from the low-pressure accumulator to the front drive motor and helps prevent
cavitation.
3.1.5 Hydraulic Power Steering System
In a full hydraulic hybrid (FHH) vehicle, the engine is mechanically decoupled from the road.
Therefore, it does not have to be running while the vehicle is propelled forward or in reverse. In
turn, the engine is not always available to drive the power steering pump as in conventional
vehicles, so an alternative system must be used to provide power steering. Since high-pressure
Thermostatic Relief Valve
High-Pressure Accumulator
Front Drive Motor
—1 I Filter
Air-to-Oil Cooler
Low-Pressure Accumulator
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hydraulic oil is always available, the obvious solution is to take advantage of this source of
power. Simply connecting a conventional rack and pinion assembly to the high-pressure
accumulator will not work, however, because conventional systems are a "flow through" design.
When steering assist is not needed, oil flows freely through the system. This type of system
would quickly deplete the accumulator pressure.
An alternative to conventional power steering, which is better suited to a FHH vehicle, is an on-
demand hydraulic assist system which allows fluid to flow to the rack only when power assist is
needed. This type of system is used on the 1975-1991 Citroen CX, which utilizes hydraulic fluid
stored in an accumulator at a pressure of 1000 psi for power steering, ride height adjustment, and
power assist brakes. The Citroen's power steering system uses a rack and pinion similar to
conventional systems combined with a pressure control mechanism to adjust pressure to the rack
based on steering wheel input.
In order to find the mass difference between the conventional system and the on-demand system,
any components which are not common to both systems are weighed and the difference is
calculated. The conventional system consists of a pump, fluid reservoir, hydraulic lines, and
steering gear assembly. The on-demand system uses a control mechanism, hydraulic lines,
pressure control valve, and steering gear assembly. The hydraulic lines for the two systems are
similar, so their mass is ignored. The control valve mechanism from the Citroen is a relatively
old design, and has not been optimized for mass reduction. A mass reduction of 1 kg is assumed
based on an analysis of similar components.
The Ford Expedition uses a recirculating ball steering gear rather than the rack and pinion used
in the Citroen. A power steering system for a FHH Expedition has not yet been developed, but
the recirculating ball steering gear could be modified to operate in the same manner as the
Citroen rack and utilize the same control mechanism. The Expedition steering gear incorporates
a control valve mechanism in the housing that is not needed for a FHH, so the mass of the
steering gear has been reduced by 2.5 kg to account for this.
A conventional system is designed
to operate at 1000 psi, while a FHH
will have fluid available at a
minimum of 2000 psi. The mass
shown for the FHH steering gear has
been reduced by 0.6 kg to account
for the smaller forcing piston that
would be allowed by the higher
pressure. Overall, a mass reduction
of 2.7 is estimated by replacing the
conventional power steering system
of the Expedition with an on-
demand power steering system (see
Table 3-3).
Table 3-3: Large SUV Power Steering System
System
Type
Conventional
Power
Steering
On-Demand
Power
Steering
Power Steering
Component
Pump, Reservoir, and Fluid
Steering Gear
Total
Control Mechanism
Steering Gear
Pressure Regulator
Total
Mass
(kg)
4.1
13.2
17.3
5.1
10.0
0.5
15.6
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Similar reductions could be realized in a midsize car. The Ford Taurus uses a rack and pinion
steering gear that can be modified to work with the Citroen control valve assembly. Because the
Taurus rack and pinion assembly includes control valves, the mass was reduced for this analysis
by 1.4 kg. Also, because the Taurus system operates at 1000 psi and the fully integrated
hydraulic hybrid will have operate
at a minimum of 2000 psi, the Table 3-4: Midsize Car Power Steering System
forcing piston can be reduced in
size, resulting in a mass savings of
0.58 kg. Overall, replacing the
conventional power steering with
an on-demand hydraulic power
steering system on a midsize car is
estimated to result in a mass
reduction of 0.5 kg (see Table 3-4).
System
Type
Convention
al Power
Steering
On-
Demand
Power
Steering
Power Steering
Component
Pump, Reservoir, and
Fluid
Steering Gear
Total
Control Mechanism
Steering Gear
Pressure Regulator
Total
Mass
(kg)
3.8
8.5
12.3
5.1
6.2
0.5
11.8
The mild hydraulic hybrid (MHH)
vehicle analyzed in this study does
not decouple the engine from the
road. Hence, like a conventional
vehicle, the engine must be running when the vehicle is propelled forward or in reverse.
Although a MHH vehicle could use an on-demand power steering system like that described for
the FHH, it is assumed for this analysis that a conventional power steering system will be
retained primarily to minimize changes to the baseline conventional vehicle. Engine shut-off
should not negatively affect power steering performance because the engine will start in a
fraction of a second after the brake pedal is released, and generate hydraulic pressure for power
steering as the vehicle begins to move. For parallel parking maneuvers, where several engine
stops may occur, an operating mode to keep the engine idling could be selected using the
automatic shift lever.
The advantages of using an on-demand system in a MHH would be seamless operation and
reduced parasitic losses. Calculations show that a high-pressure accumulator in a MHH would
provide adequate fluid for the power steering even if the steering wheel is turned from lock to
lock repeatedly while the vehicle is not moving.
3.1.6 Battery, Alternator, and Starter System
Because the engine can be shut off in a HHV during typical operation, some means of driving the
alternator to maintain battery charge must be added for certain hybrid configurations. In
addition, more frequent engine starting, if accomplished using a conventional starter, would
require a larger battery to handle the higher usage. However, the need for accessory drive
modifications depends on the exact hybrid configuration, with some requiring no change at all
from the conventional system.
For MHHs or FHHs using a strategy where the engine runs at all times (engine-on strategy), no
change is required for the battery, alternator, or starter. The alternator is driven directly by the
engine and the battery requirements and starter usage are the same as in a conventional vehicle.
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It is possible to reduce the size of the battery and starter in FHHs because the engine P/M is
available to help start the engine. However, this analysis conservatively assumes that the battery
and starter in a FHH are the same size as that used in the conventional vehicle.
For MHH vehicles with "engine off strategies, there is an increased demand on the battery to
restart the engine. Based on the 1994 Volkswagen Golf Ecomatic, which featured an engine-off
strategy, it is estimated that a 25 percent larger battery would be required. Since the engine duty
cycle is still high for a MHH vehicle even with on/off operation, no change is required of the
alternator. The stock starter is retained and used as in a conventional vehicle, although with a
higher frequency of starts.
For the FHH vehicles with engine-off strategies, the engine duty cycle (the amount of time the
engine runs compared to total vehicle drive time) is significantly reduced. Depending on the
engine used, engine duty cycle can be as low as 20 percent during city driving. For low engine
duty cycle configurations, a hydraulically driven alternator is added to keep the battery charged.
The hydraulically driven alternator combines a conventional alternator with a fixed displacement
hydraulic motor controlled by a pulse-width modulated flow control valve. The alternator mount
for the hydraulically motor and valve is offset by elimination of the pulley from the conventional
alternator.
Engine starting in a FHH vehicle is accomplished using either the electric starter or the engine
P/M or both. The conventional starter is retained because there may occasionally be insufficient
pressure in the high-pressure accumulator to start the engine. In this case, the electric starter
kicks the engine and the hydraulic motor helps the starter to reduce amperage draw. If system
pressure is high enough, the engine P/M starts the engine on its own. Using this strategy to
reduce battery draw during frequent starts, the battery can be kept the same size as in the
conventional vehicle. In fact, because the P/M is available to help the electric starter, it is likely
that the battery size and starter size could be reduced in FHH configurations with engine-off
strategies. However, this study conservatively assumes no reduction in the battery or starter size
for the FHH vehicles.
3.1.7 General Hydraulic Fittings And Hoses
The hydraulic oil in a HHV is contained and directed to the pumps, motors, valves and
accumulators by hoses, tubes and fittings. Tubes are steel lines with brazed or flared end
connections. Hoses are rubber conduits, reinforced with fibers or steel wire or braids. Fittings
are connectors, adapters, and end pieces for the hoses and tubes. It is desirable to keep the
number of fittings and connections in the vehicle low because each connection adds complexity
and cost to the vehicle and is a potential leak point.
To keep pressure drops to an acceptable level for high efficiency and to minimize mass, cost, and
space allocated to the oil conduits, 1" ID lines are used for the high-pressure P/M connections,
and 1.25" ID lines are used for the low-pressure P/M connections. The mass of these lines is 2.2
kg/m for the high-pressure lines and 1.2 kg/m for the low-pressure lines. Because the number
and type of fittings is highly dependent on the configuration, mass estimates of total fittings used
will be given for each vehicle configuration below.
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3.2 Four Hydraulic Hybrid Configurations
This subsection describes four hydraulic hybrid configurations. These are 1) Full Hydraulic
Hybrid SUV (FHHSUV), 2) Mild Hydraulic Hybrid SUV (MHHSUV), 3) Full Hydraulic
Hybrid Car (FHHCAR), and 4) Mild Hydraulic Hybrid Car (MHHCAR). For each
configuration, a vehicle layout is presented detailing hydraulic component sizes and function. In
addition, unique features of the configuration are described and mass estimates are given for
conventional components removed and HHV components added. The mass estimates are used to
project incremental costs for the hybrid technology packages later in Section 6. It is important to
emphasize that there are a large number of possible designs for each of the four configurations.
Plausible designs have been chosen based on EPA experience, but it is likely that further
improvements would be made if and when hydraulic hybrid designs are commercialized.
Figure 3-4: FHHSUV Configuration
I35cc/iev f N^
^ CJ_)
3.2.1 Full Hydraulic Hybrid SUV
A FHHSUV could be configured in
many unique ways depending on the
tradeoffs associated with packaging,
cost, fuel economy, acceleration
performance, etc. This analysis focuses
on one plausible configuration that
EPA believes is representative of the
various options available. The
configuration was designed to have
similar launch feel, 0-60 mph
acceleration time, and towing capability
as the baseline conventional vehicle.
Figure 3-4 presents the basic FHHSUV
configuration used for this analysis.
In this configuration, the automatic
transmission is replaced with a
hydraulic hybrid drivetrain. A 4.6 L gasoline engine replaces the baseline 5.4 L engine. (For the
diesel full hydraulic hybrid, a 3.8 L engine replaces the original diesel engine.) This is possible
because the hydraulic drivetrain with the 4.6 L engine provides comparable O-to-60 mph
acceleration. In addition, high-power towing can be handled with the smaller engine because
peak engine output can be delivered at any vehicle speed in a FHH, while engine power is
somewhat limited by discrete ratios inherent in conventional transmissions.
The engine is coupled to a 135 cc/rev hydraulic pump/motor (P/M), which operates as a pump to
supply hydraulic power to the drive motors and/or to fill the high-pressure accumulator as
needed. The engine P/M can also be used to start the engine when operated as a motor.
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A 110 cc/rev hydraulic P/M is integrated into the front differential. The front P/M is operated in
a motor mode to accelerate the vehicle, in a pump mode to slow the vehicle down by capturing
kinetic energy, and in a reverse mode for vehicle reverse. The various modes are accomplished
through the use of a flow control valve integrated into the P/M housing.
A 110 cc/rev motor is integrated into a rear drive assembly which also includes a two-speed
gearbox and a differential. The rear motor operates in a motor mode to accelerate the vehicle
and in a reverse mode for vehicle reverse; it is not used for regenerative braking. The rear
motor/gearbox/differential (discussed in greater detail below) is capable of delivering
significantly greater torque than the front drive unit to give the vehicle good launch acceleration.
The front and rear units can be used independently or together to provide the most efficient
transfer of energy to the wheels.
Figure 3-5: Front
Pump/Motor/Differential Assembly
^-Front of Vehicle
Differenlial
Front Pump/Motor/Differential Assembly
The front power unit combines a P/M and the
differential into a common housing. The
assembly consists of a 110 cc/rev unit and
differential with a 4.5:1 final drive ratio. P/M
speed at a vehicle speed of 161 km/hr (100 mph)
is estimated to be 4700 rpm. The layout of the
system is illustrated in Figure 3-5. Alternatively,
a helical gear set could be used for the differential
in place of the conventional hypoid gear set
shown. Combining the P/M into the same housing
as the differential eliminates the front drive shaft
from the conventional 4WD SUV, which has a
mass of 5.0 kg.
To estimate the mass increase of adding a P/M to the front base front differential, the mass of the
stand alone SAE 4-bolt flange 110 cc/rev hydraulic unit was adjusted down to account for the
savings from integrating the P/M with the differential housing. It is estimated that the P/M mass
could be reduced by 8 kg (from 37.2 kg to 29.2 kg) by: 1) eliminating the drive flange, front
bearing, and part of the pinion shaft from the base differential, 2) eliminating the SAE mount,
front bearing, and a portion of the input shaft from the stand-alone P/M, and 3) adding housing to
combine the two components together.
The front drive unit is designed to efficiently provide torque for moderate accelerations and
decelerations typical of normal driving. Heavy accelerations are accomplished by using both the
front and rear hydraulic power units. The front power unit decelerates the vehicle when operating
as a pump to capture energy normally lost to friction brakes in a conventional vehicle. The unit is
sized to capture energy from normal, moderate braking events (deceleration events of less than
0.15 g), and is supplemented by friction brakes for more aggressive braking.
Rear Motor/Gearbox/Differential Assembly
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The basic components of the rear assembly envisioned by EPA include a motor, gear reduction,
clutch out mechanism, and a differential. Depending on the size of the motor and the gearing
option chosen, a FHHSUV can be configured to provide limited 4WD capability (low speeds
only for lower costs) or full 4WD performance similar to that offered on current SUVs. For this
analysis, a rear drive system with full 4WD capability was chosen to allow comparison with a
conventional 4WD SUV. The system consists of a 110 cc/rev P/M, a 2-speed planetary gearbox
with two forward ratios and a geared neutral, and differential with 4.0:1 final drive. The
components are integrated into one combined housing as part of an independent rear suspension.
The overall layout of the system is
given in Figure 3-6 Alternatively, a Figure 3-6: Rear Motor/Gearbox/Differential
helical gear set could be used for the Assembly
differential instead of the hypoid
arrangement shown.
^Front of Vehicle
In low gear, a planetary ratio of 3.5:1
gives the same launch torque as the
conventional SUV. In high gear, the
planetary ratio is 1:1, which lowers
motor speeds for 4WD use at highway
speeds. The geared neutral operating
mode of the planetary is used to
reduce spin losses from the motor at
highway speeds for increased fuel
efficiency when 4WD is not selected.
The motor portion of the integrated system is approximately 37 kg, nearly the same as the base
stand-alone motor described in Subsection 3.1.1. For this analysis, the motor flow control valve
is designed to allow both forward and reverse operation. However, depending on the overall
gearing approach used, a geared reverse may be the more cost-effective design.
The motor bearings support the sun gear of the planetary, while the ring and carrier are supported
by the differential pinion gear bearings. The three modes of operation in the planetary are
obtained using a band clutch on the ring gear and a multi-disk clutch between the ring gear and
carrier. The mass of the planetary section of the system, including planetary gears, clutches,
clutch actuation valves, and housing is estimated to be 10 kg. The differential portion of the
assembly remains largely unchanged from the baseline vehicle, except for the elimination of the
drive shaft flange, which was taken into account in the above estimate. The motor section of the
assembly is based on the prototype EPA design, and is included in the mass summary table for
the FHHSUV (Table 3-8). Mounts for the system are similar in mass to the mounts for the base
differential, with one large mount integrated into the differential cover (not shown in the figure)
and a second mount near the large bearing of the motor to react the wheel torque.
Engine Pump Mount
The engine P/M mount is an aluminum bell housing bolted to the block. The bell housing
accepts the 4-bolt flange of the base P/M and the splined shaft of the P/M fits directly into the
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crankshaft. A second rear mount (similar to the rear mount for the base automatic transmission)
is present on the P/M to stabilize the engine and P/M. Thus, there no mass increase associated
with the rear mount P/M mount. The mass of the bell housing for the main 4-bolt mount is
estimated to be 5.3 kg.
Battery/Alternator/Starter and Power Steering Systems
As explained in Subsection 3.1.6, the FFtHSUV will utilize a hydraulically driven alternator for
all engine-off strategy engine options. The hydraulically driven alternator allows the battery to
charge when engine duty cycle is too low, which would occur during extended periods of city
driving. The hydraulically driven alternator adds 4 kg for a 4 cc hydraulic motor and 0.5 kg for a
PWM control valve, for a total of 4.5 kg over the base conventional vehicle's alternator system.
The battery size and starter remain unchanged.
The conventional power steering system is replaced with an on-demand power steering system
fed by the high-pressure accumulator (as described in Subsection 3.1.5). The mass of the on-
demand power steering system is projected to be 1.7 kg less than the base conventional system.
Hydraulic Circuit
Figure 3-7 presents the hydraulic circuit diagram for the FFtHSUV. The line lengths in the
diagram are used to estimate the mass of lines and hoses, fittings, and oil contained in the
system. The line length and hose routing estimates are based on dimensions of a 1999 Ford
Expedition. Table 3-5 gives mass estimates for the fluid conduits used to carry fluid throughout
the system. Tables 3-6 and 3-7 provide estimates of the amount of oil in the hydraulic circuit,
and the mass of the oil conditioning system, respectively.
Figure 3-7: FHHSUV Hydraulic Circuit Diagram
D-B-o
t High Pressure Line
Hydaiiic Power Steering System (HPSS)
HydaiiicallyQiven Alternator System(HDAS)
LcwPressureLire Oil CcnditicningSyEtem(OCS)
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Table 3-5: FHHSUV Fluid Conduit Mass Summary
Component
Main Loop Hose/Tube
Accessory Loop Hose/Tube
Fittings/Hose ends
Sub Totals
High Pressure
Length
(m)
2
1
Mass
(kg)
4.4
0.5
17.4
22.3
Low Pressure
Length
(m)
2.0
1.0
Mass
(kg)
2.4
0.1
8.5
11.0
Total: 33.3
Table 3-6: FHHSUV Oil Mass Summary
Component
Accumulator
Pumps
Oil Conditioning System
Fluid Conduits
Total:
Volume
(L)
28.4
12.1
3.0
2.7
46.3
Mass
(kg)
23.8
10.2
2.5
2.3
38.8
Table 3-7: FHHSUV Oil Conditioning
System Mass Summary
Component
Frlter
Oil to Air Cooler
Valves and Manifold
Mount
Total:
Mass (kg)
2
4
2.5
1
9.5
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FHHSUV Mass Summary
Table 3-8 summarizes the mass of components added and removed for the FHH SUV
configuration. The component mass will be grouped into categories of similar manufacturing
complexity to estimate cost in Section 6.
Table 3-8: FHHSUV Mass Summary
Gas Engine with Engine Off Strategy
Category
P/Ms
Accumulators
Gearbox
Hydraulic circuit
Accessories
Brackets & Mounts
Components Removed
Component
135 cc engine pump motor (w/ mounting flange and bearing)
1 10 cc pump motor (combined fit power unit saves 8 kg est.)
1 10 cc motor for rear power unit
15 gal composite accumulator (high pressure)
15 gal composite accumulator (low pressure)
2 speed planetary (w/housing) for rear power unit
oil cooler and filter loop (front motor low side) + mount
fitting and hoses
fluid in HP accumulator, fittings, hoses, oil conditioner
hydraulic driven alternator
on-demand power steering system
accumulator mounting brackets
engine/PM coupling and fasteners
engine downsize
automatic transmission
transfer case
net downsize of fuel tank
rear drive shaft
front drive shaft
transmission cooler and lines
transmission fluid
power steering system (pump, reservior, steering gear)
TOTAL MASS ADDED
Mass
(kg)
45.7
29.2
37.2
56.0
23.4
15.0
9.5
33.3
38.8
4.5
15.6
6.0
5.3
-31.0
-106.0
-47.3
-2.4
-9.8
-7.3
-1.8
-11.8
-17.3
84.8
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3.2.2 Mild Hydraulic Hybrid SUV
Figure 3-8: MHHSUV Configuration
Figure 3-8 presents the MHHSUV assumed in this analysis. The configuration was designed to
have similar launch feel, 0-60 mph acceleration time, and towing capacity as the baseline
conventional vehicle. In this
configuration, the base 5.4 L engine and
automatic transmission are retained. In
addition, a 110 cc/rev hydraulic P/M is
integrated into the 4WD transfer case
along with a 1.35:1 helical gear set.
The P/M is operated in a motor mode to
assist the transmission in accelerating the
vehicle, and operated in a pump mode to
slow the vehicle down by capturing kinetic
energy. The P/M modes are accomplished
through the use of a flow control valve
integrated into the P/M housing. The
speed of the P/M is 5000 rpm at 161 km/hr
(100 mph).
The P/M is used primarily to capture vehicle kinetic energy. The energy is stored in a 26.5 L (7
gallon) accumulator and reused during the next acceleration. The system operates exactly like the
base conventional system whenever the P/M is offline.
Integrated Transfer Case and Pump/Motor
A 110 cc/rev P/M is integrated into
the transfer case housing through a
1.35:1 gear ratio. The layout shown
(Figure 3-9) assumes that the
electronic shift servo is repositioned
slightly and the transfer case
housing strengthened somewhat to
accommodate the addition of the
P/M. Overall, it is estimated that the
gear set and housing additions
would add 3.5 kg to the individual
mass of the base transfer case and
stand-alone P/M. A vehicle mount
is attached to the P/M to supplement
the existing transfer case mount at
the transmission interface, adding
1.0 kg, for an overall addition of 4.5
kg.
Figure 3-9: Integrated Transfer Case and P/M
Transfer
Case
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A more integrated package could be achieved using a 148 cc/rev unit with no gear reduction.
However, overall mass would be roughly equal to that in the layout shown in Figure 3-9, as
savings from greater integration would be offset by the increased mass of the P/M.
Battery/Alternator/Starter and Power Steering System
As discussed in Subsection 3.1.6, a MHHSUV with an engine-off strategy requires 25 percent
greater battery capacity to handle the increase starter load, resulting in a battery mass increase of
5.2 kg. No change is required for the alternator because the engine shuts off only at zero vehicle
speed, keeping engine duty cycle high enough to charge the battery using the conventional
charging system. The stock starter is retained and used as in a conventional SUV, although with
a higher frequency of starts.
The MHHSUV uses a conventional power steering system to keep changes to the base
conventional vehicle to a minimum. Optionally, an on-demand power steering system (as
described in Subsection 3.1.5) could be used to take advantage of the hydraulic pressure in the
accumulator and reduce parasitic losses. The choice between power steering options may vary
depend on the vehicle application and anticipated sales volume of the MHHSUV in relation to
the conventional configuration.
Hydraulic Circuit
Figure 3-10 contains the hydraulic circuit diagram for the MHHSUV. The diagram is used to
estimate the mass of lines and hoses, fittings, and oil contained in the system. The line length and
hose routing estimates are based on dimensions of a 1999 Ford Expedition. Table 3-9
summarizes the mass of the fluid conduits for the MHHSUV. Table 3-10 gives the amount of oil
in the hydraulic circuit, and Table 3-11 present the mass estimates for oil conditioning system.
Descriptions of these components are given in Subsection 3.1, as it applies to the MHHSUV.
Figure 3-10: MHHSUV Hydraulic Circuit Diagram
» High Pressure Line
Low Pressure Lire aiCcnditicningSystem(OCS)
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Table 3-9: MHHSUV Fluid Conduit Mass Summary
Component
Main Loop Hose/Tube
Accessory Loop Hose/Tube
Fittings/Hose ends
Sub Totals
High Pressure
Length
(m)
0.5
0
Mass
(kg)
1.1
0.0
4.2
5.3
Low Pressure
Length
(m)
0.5
0.0
Mass
(kg)
0.6
0.0
2.1
2.7
Total: 8.1
Table 3-10: MHHSUV Oil Mass Summary
Component
Accumulator
Pumps
Oil Conditioning System
Fluid Conduits
Total:
Volume
(L)
12.8
3.8
2.5
0.6
19.7
Mass
(kg)
10.7
3.2
2.1
0.5
16.5
Table 3-11: MHHSUV Oil
Conditioning System Mass Summary
Component
Filter
Oil to Air Cooler
Valves and Manifold
Mount
Total:
Mass (kg)
2
3
2.5
1
8.5
MHHSUV Mass Summary
Table 3-12 summarizes the mass of components added and removed for the MHHSUV
configuration. The component mass will be grouped into categories of similar manufacturing
complexity to estimate cost in Section 6.
Table 3-12: Mass Summary for MHHSUV
Gas Engine with Engine Off Strategy
Category
P/Ms
Accumulators
Gearbox
Hydraulic circuit
Accessories
Brackets & Mounts
Components Removed
Component
1 10 cc pump motor (w/mounting flange for transfer case)
7 gal composite accumulator (high pressure)
7 gal composite accumulator (low pressure)
1.4 gearset integrated into transfer case
oil cooler and filter loop (front motor low side)
fitting and hoses
fluid in HP accumulator, fittings, hoses, oil conditioner
Battery up size
accumulator mounting brackets
pump motor isolation mount (in addition to transfer case mount)
net downsize of fuel tank
TOTAL MASS ADDED
Weight
(kg)
37.7
32.3
14.3
3.5
8.5
8.1
16.9
5.2
4.5
1.0
-1.3
130.7
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3.2.3 Full Hydraulic Hybrid Car
Similar to the FHHSUV, a FHHCAR can be configured many different ways depending on
tradeoffs associated with packaging, cost, fuel economy, acceleration performance, etc. A front-
wheel drive configuration is shown
in Figure 3-11. In this
configuration, all the P/Ms are
CD
Figure 3-11: FHHCAR Configuration
2.5 L
located in the front of the vehicle
in a single combined housing.
Alternatively, a FHHCAR could be
configured in an all-wheel drive
arrangement, with one motor
connected to the rear wheels
through a differential. For this
analysis, the front-wheel drive
layout was chosen to compare
directly to the baseline midsize car.
The key components are sized to provide performance equivalent to the baseline conventional
vehicle while maximizing fuel efficiency. Energy stored in the hydraulic accumulators and
engine operation flexibility possible in a hydraulic powertrain allow the baseline 3.0 L V6 engine
to be downsized to a 2.5 L gasoline engine. (For the diesel full hydraulic hybrid, a 2.3 L engine
replaces the original diesel engine.) In addition, the torque converter and automatic transmission
of a conventional car are replaced with an integrated hydraulic transaxle including an engine
P/M, one drive P/M, one drive motor, and a one-way clutch.
The P/Ms are used in a manner similar to the FHHSUV described earlier in Subsection 3.2.1.
The 80 cc/rev engine P/M is used to start the engine and then operates as a pump to supply
hydraulic power. The 65 cc/rev drive P/M is used to propel the vehicle, in forward and reverse,
and brake the vehicle. This P/M delivers a large majority of the energy to and from the wheels
during typical driving. The 90 cc/rev motor can deliver significantly more torque to the wheels
and is used to provide good acceleration for the vehicle in forward and reverse. This motor is
coupled with a one-way clutch to reduce the introduction of parasitic losses to the drivetrain
when it is not being used. Finally, for energy storage there is a 37.9 L (10 gallon) high-pressure
accumulator and a 37.9 L (10 gallon) low-pressure accumulator.
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Integrated Hydraulic Transaxle
All of the P/Ms and the clutch are integrated into
one hydraulic transaxle. Each drive motor has its
own pinion gear to provide a unique ratio with the
ring gear of the differential. A potential layout of
the system is shown in Figure 3-12. The overall
layout is similar in size to the baseline conventional
automatic transmission. To minimize complexity,
the hydraulic transaxle is connected to accumulators
through one high and one low-pressure hose/line.
Individual fluid conduits connect the individual
P/Ms within the transaxle. The estimated mass of
the transaxle excluding the P/Ms is 41.3 kg. The
estimate is based on a prototype layout designed by
an EPA contractor.
Figure 3-12: FHHCAR Integrated
Hydraulic Transaxle
Battery/Alternator/Starter and Power Steering Systems
The FHHCAR is similar to the FHHSUV with regards to the battery/alternator/starter and power
steering systems. A hydraulically driven alternator, which combines a 3 cc hydraulic unit, a
control valve, and an alternator, adds 3.5 kg compared to the base alternator system. The mass
of the on-demand power steering system is projected to be roughly the same (see Subsection
3.1.5) as the base conventional system.
Hydraulic Circuit
Figure 3-13 contains the hydraulic circuit diagram for the FHHCAR. The diagram is used to
estimate the mass of lines and hoses, fittings, and oil contained in the system. The line length
and hose routing estimates are based on dimensions of a 1999 Ford Taurus. Tables 3-13, 3-14,
and 3-15 give a summary of mass estimates for these components.
Figure 3-13: FHHCAR Hydraulic Circuit Diagram
lit egrated Hydauli c
TiansaxJewith
Ci 1C oiditi cning SyS em
and Hydraiiically Driven
Al ter nator S \stem
D
> High Pressure Line
Low Pressure Lire
HyAauUc Power Steering System (HPSS)
HyAauUrallyQiven Alternator System(HDAS)
Ql Ccnditicning System (OCS)
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Table 3-13: FHHCAR Fluid Conduit Mass Summary
Component
Main Loop Hose/Tube
Accessory Loop Hose/Tube
Fittings/Hose ends
Sub Totals
High Pressure
Length
(m)
3
0.5
Mass
(kg)
6.6
0.3
4.5
11.4
Low Pressure
Length
(m)
1.0
0.5
Mass
(kg)
0.8
0.1
2.2
3.0
Total: 14.4
Table 3-14: FHHCAR Oil Mass Summary
Component
Accumulator
Pumps
Oil Conditioning System
Fluid Conduits
Total:
Volume
(L)
18.9
7.7
2.5
2.1
31.2
Mass
(kg)
15.9
6.5
2.1
1.8
26.2
Table 3-15: FHHCAR Oil Conditioning
System Mass Summary
Component
Frlter
Oil to Air Cooler
Valves and Manifold
Mount
Total:
Mass (kg)
1
3
1.5
0.5
6
FHHCAR Mass Summary
Table 3-16 summarizes the mass of components added and removed for the FHHCAR
configuration.
Table 3-16: Mass Summary for FHHCAR
Category
P/Ms
Accumulators
Gearbox
Hydraulic circuit
Accessories
Brackets & Mounts
Components Removed
Component
80 cc pump motor
65 cc drive motor
80 cc drive motor
10 gal composite accumulator (high pressure)
10 gal composite accumulator (low pressure)
integrated transmission (w/o motors)
oil cooler and filter loop (front motor low side)
fitting and hoses
fluid in HP accumulator, fittings, hoses, oil conditioner
hydraulic driven alternator
on-demand power steering system
accumulator mounting brackets
engine downsize
automatic transmission
net downsize of fuel tank
transmission fluid
power steering system (pump, reservior, steering gear)
TOTAL MASS ADDED
Mass
(kg)
27.1
22.0
27.1
41.7
18.1
41.3
6.5
14.4
24.1
3.5
11.8
6.0
-21.0
-85.0
-4.1
-10.0
-12.3
111.1
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Figure 3-14: MHHCAR Configuration
3.2.4 Mild Hydraulic Hybrid Car
Figure 3-14 presents the Mild Hydraulic Hybrid Car (MHHCAR) configuration assumed in this
analysis. The configuration was designed to have similar launch feel and 0 to 60 mph
acceleration time as the baseline conventional vehicle. In this configuration, the baseline 3.0 L
engine and automatic transmission
are retained and a 55 cc/rev
hydraulic P/M is integrated into the
transmission. The P/M is sized to
capture the energy from normal
braking and weighs 18 kg. For
comparison, the AX4N automatic
transmission used in the Ford
Taurus weighs approximately 85
kg (dry). There is a 1.27:1 gear
reduction from the P/M to the
transmission. This reduction,
coupled with a final drive ratio of
3.77:1 produces an overall ratio of 4.79:1. Therefore the P/M can provide or absorb over 1400
N-m of torque at the wheels. Finally, for energy storage there is a 15.1 L (4 gallon) high-
pressure accumulator and a 15.1 L (4 gallon) low-pressure accumulator.
no
Figure 3-15: MHHCAR Transaxle
Vertical cross-section
view as seen from
driver's seat forward
toward engine
approximate vertical profile of
transverse V6 engine
Integrated P/M and Automatic Transmission
The layout of the integrated P/M and
automatic transmission system is
presented in Figure 3-15. The P/M is
oriented with its drive shaft parallel to
the transmission axle shafts. The
connection between the P/M and
transmission is accomplished through the
use of a chain drive similar to the chain
between the input shaft and main
transmission shaft in the Taurus AX4N
transmission and many other front wheel
drive automatics. A P/M mount is added
to the automatic transmission and
housing strength is increased to support
the additional mass of the P/M. Also, the
transmission is slightly longer to
accommodate the extra gear & chain
assembly that connects the P/M to the
transmission. The estimated mass
increase over the baseline automatic
transmission resulting from the addition of the chain drive and P/M mount is 8.3 kg.
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Battery/Alternator/Starter and Power Steering System
Similarly to a MHHSUV, a MHHCAR with an engine-off strategy requires 25 percent greater
battery capacity to handle the increase starter load, resulting in a battery mass increase of 4.6 kg.
No change is required for the alternator or starter (see Subsection 3.1.6). A conventional power
steering system is used on the MHHCAR as described in Subsection 3.1.5 to keep changes to the
base conventional vehicle to a minimum.
Hydraulic Circuit
Figure 3-16 contains the hydraulic
circuit diagram for the MHHCAR.
The schematic is used to estimate
the mass of lines and hoses, fittings,
and oil contained in the system. The
line length and hose routing
estimates are based on dimensions
of a 1999 Ford Taurus. Tables 3-17,
3-18, and 3-19 give a summary of
mass of the hydraulic components
for the MHHCAR.
Figure 3-16: MHHCAR Schematic
I High fressuie Line
Low fressure Line
Oil Ccnditicning System (OCS)
Table 3-17: MHHCAR Fluid Conduit Mass Summary
Component
Main Loop Hose/Tube
Accessory Loop Hose/Tube
Fittings/Hose ends
Sub Totals
High Pressure
Length
(m)
3
0
Mass
(kg)
6.6
0.0
4.2
10.8
Low Pressure
Length
(m)
1.0
0.0
Mass
(kg)
0.8
0.0
2.1
2.9
Total: 13.8
Table 3-18: MHHCAR Oil Mass Summary
Component
Accumulator
Pumps
Oil Conditioning System
Fluid Conduits
Total:
Volume
(L)
7.6
1.9
2.5
2.0
14.0
Mass
(kg)
6.3
1.6
2.1
1.7
11.7
Table 3-19: MHHCAR Oil Conditioning
System Mass Summary
Component
Filter
Oil to Air Cooler
Valves and Manifold
Mount
Total:
Mass (kg)
1
3
2
1
7
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MHHCAR Mass Summary
Table 3-20 summarizes the mass of components added and removed for the MHHCAR
configuration.
Table 3-20: MHHCAR Mass Summary
Category
P/Ms
Accumulators
Gearbox
Hydraulic circuit
Accessories
Brackets & Mounts
Components Removed
Component
55 cc pump motor
4 gal composite accumulator (high pressure)
4 gal composite accumulator (low pressure)
additional input to final drive of trans, extra housing, mounts, chain
oil cooler and filter loop (front motor low side)
fitting and hoses
fluid in HP accumulator, fittings, hoses, oil conditioner
battery up size
accumulator mounting brackets
net downsize of fuel tank
TOTAL MASS ADDED
Weight
(kg)
18.6
24.0
11.2
8.3
5.0
13.8
9.6
4.6
4.0
-1.8
97.3
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4. Vehicle Technology Packages and Modeling Scenarios
This progress report evaluates four basic technology approaches that could improve vehicle fuel
economy: mild hydraulic hybrid drivetrains, full hydraulic hybrid drivetrains, clean diesel
engines, and variable displacement engines. As will be explained below, these individual
technologies, when grouped into reasonable packages, leads to a total of 40 vehicle technology
packages defined by three different dimensions:
> 2 vehicle classes
> 5 drivetrain configurations
> 4 engine configurations
4.1 Two Vehicle Classes
Midsize cars with front wheel drive and large sport utility vehicles (SUVs) with 4-wheel drive
are the two vehicle classes chosen to simplify this analysis. In EPA's Fuel Economy Trends
report, one classification methodology for new vehicles involves dividing the fleet into 16
different classes: two-seater cars, minicompact cars, subcompact cars, compact cars, small
station wagons, midsize cars, midsize station wagons, large cars, small SUVs, mid SUVs, large
SUVs, minivans, small pickups, midsize pickups, large pickups, and large vans. (Some analyses
also include medium-duty passenger vehicles, the largest SUVs and passenger vans in excess of
8500 pounds gross vehicle weight rating, as a 17th personal vehicle class.) Carrying out this
technology evaluation for all 16 or 17 vehicle classes, rather than the 2 chosen vehicle classes,
would greatly increase the number of vehicle technology scenarios. Instead, EPA staff chose to
focus on two vehicle classes which, because of their high sales volumes and relatively low fuel
economies, have the potential to yield large aggregate fuel and carbon savings: midsize cars
(e.g., Chevrolet Monte Carlo, Toyota Camry) and large SUVs (e.g., Dodge Durango, Ford
Expedition). These two classes alone represent about one-quarter of the overall personal vehicle
market and a higher proportion of overall fuel use and carbon emissions. The baseline midsize
car uses front wheel drive, while the baseline SUV uses 4-wheel drive. The impact of various
technology packages on fuel economy and cost for these high-volume classes will "carry over"
to other vehicle classes in varying degrees, but it seemed most appropriate to focus initially on
high-volume vehicle classes with relatively low fuel economies.
4.2 Five Drivetrain Configurations
There are 5 transmission/hydraulic hybrid drivetrain configurations. The first simply involves
the conventional transmission that is standard on nearly all personal vehicles today. The second
and third cases involve mild hydraulic hybrid drivetrains, differing only in whether the
powertrain strategy never shuts the engine off except when the driver explicitly does so (i.e.,
engine-on strategy) or does in fact shut the engine off during times when the engine power is not
needed and when overall vehicle efficiency can be increased by shutting the engine down
(engine-off). The fourth and fifth scenarios involve full hydraulic hybrid drivetrains, again with
both engine-on and engine-off approaches. Hydraulic hybrid drivetrains in general are briefly
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 52
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described in Section 2 and specific hydraulic hybrid vehicle designs are described in greater
detail in Section 3. It is important to note that consumer acceptance of the frequent engine
cycling associated with the engine-off strategy is unknown at this time.
4.3 Four Engine Configurations
There are 4 engine technology configurations. The first is simply the conventional gasoline
engine that is used on nearly all personal vehicles today. The second configuration is a clean
diesel engine able to meet Tier 2 emission standards. The third is a variable displacement
gasoline engine. The fourth is the one engine configuration that involves two changes: both a
clean diesel engine and variable displacement. This configuration makes technical sense because
the diesel cycle improves basic combustion efficiency over the full range of engine operating
conditions, while variable displacement increases the frequency of engine operation at or near
the regions of peak efficiency.
Table 4-1 shows the 40 vehicle technology packages, of which 2 are baselines (i.e., represent
today's vehicles with conventional gasoline engines and conventional transmissions) and the
remaining 38 are the technology packages evaluated in this study.
Table 4-1: 40 Vehicle Technology Packages
/ r\ r^1 j
Large Sport Utility Vehicle
(4WD) '
Fuel Economy (MPG) *
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
(base)
X
X
X
X
X
X
X
! x
! x
1 x
1 x
x !
x !
x 1
x I
X
X
X
X
Midsize Car
(2WD)
Fuel Economy (MPG) *
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
(base)
x
x
x
x
x
x
x
x
! x
! x
1 X
X
x !
x !
X 1
X
X
X
X
* Fuel economy values are laboratory values and are about 15% higher than real-world projections.
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5. Projection of Fuel Economy Improvement Potential
5.1 Overview
EPA staff developed a new modeling tool called the Stored Hydraulic Energy Research Platform
Analyzer (SHERPA), using Matlab and Simulink on a desktop personal computer, to project
likely fuel economy levels for the 40 vehicle technology scenarios. The model is designed to be
able to simulate operation of vehicles with all of the unique engine and drivetrain designs
included in the 40 vehicle technology configurations. For each scenario and driving cycle
studied, the model produces a summary file including statistics for each of the vehicle's
components and an energy balance table to show where the fuel energy was consumed either by
internal losses or vehicle propulsion.
The major inputs to the model are the vehicle roadload specification, vehicle mass, the efficiency
maps of the engines and hydraulic components, the control strategy, and the driving cycles.
The vehicle roadload specification determines the amount of
force required to propel the vehicle as a function of vehicle
speed. The baseline 4WD large SUV had a test weight of
5563 pounds and the baseline midsize car had a test weight of
3517 pounds. For modeling scenarios involving changes to
the powertrain, the masses of component packages were added
to or subtracted from the baseline vehicle to estimate the total
mass for each configuration. With respect to two other important components of vehicle
roadload, EPA assumed that vehicle aerodynamic drag and tire rolling resistance were similar to
today's production vehicles. Automobile manufacturers provide roadload equations to EPA as
part of the vehicle emissions certification and fuel economy testing programs, and EPA
generated representative values for the modeling scenarios by performing a simple sales-
weighted analysis of the roadload equations for the top-selling vehicles in both the large SUV
and midsize car classes.
To model the various engines, representative engine maps (fuel energy efficiency as a function
of load and RPM) based on manufacturer or in-house data were used, scaled to match the
vehicle's power and torque requirements. Appendix E gives the 4 basic engine maps that are
used in this report: for the base gasoline and diesel engines for both the large SUV and the
midsize car applications. Maps for the variable displacement engines were modifications of
these engine maps. Appendix F gives the efficiency maps for the hydraulic pump/motors, which
were based on efficiency data from prototype units developed and tested by EPA.
The control strategies are fairly straightforward, based on first-order approaches to hydraulic
hybrid vehicle operation and direct EPA experience with in-house hydraulic hybrid vehicle test
chassis. It should be noted that for the large number of fuel economy modeling scenarios it was
not possible to optimize the control strategy for each in the time available for this study. For this
reason, there are only relatively minor changes in strategy for each fuel economy modeling
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 54
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scenario. Any production vehicle would have an optimized strategy that would likely produce
higher fuel economy than the results projected in our modeling.
The driving cycles used are the standard Federal Test Procedure (FTP) city and highway cycles
used to measure the fuel economy and emissions of conventional vehicles. These driving cycles
are used to generate the fuel economy test data that is then adjusted (to better reflect what
consumers will achieve in real world driving) to provide the fuel economy label values displayed
on showroom vehicles and in the EPA/DOE Fuel Economy Guide. The city label number is
90% of the city test result and the highway label number is 78% of the highway test result.
Unless noted otherwise, the fuel economy values shown in this report are unadjusted, combined
city/highway fuel economy test values, which are approximately 15% higher than the projected
real-world values on new car labels and in the Fuel Economy Guide.
Figure 5-1 is a diagram of the top level for the fuel economy modeling of a mild hydraulic hybrid
vehicle showing the basic flow of information among the different parts of the model. The
model is a "forward" model for which results flow from a driver torque request to a vehicle
response. The model "driver" compares the actual vehicle speed with the vehicle speed desired
by the driving cycle and requests positive or negative torque at the wheels as required. This
modeling method is computationally expensive (i.e. not as fast as we might like) but has the
advantage of following the same basic principles as an actual vehicle and driver.
Figure 5-1: Mild Hydraulic Hybrid Fuel Economy Modeling Diagram
Launch Assist Vehicle Morfe/
Cyber Driver
Command Torque Nrn
Turbine RPM gals
Lockup
vspeed m/s Tortlue Mm
Drake Torque Nm
line State"™1* Throttle
r& Engi
Engine/Torque Converter
Sys MPa
DesWheelTrq Nm
Trans RPM
Wheel RPM
\&peed m/s DrakeTorque Nm
ERPM
Stored Energy kW-s
Etorque Nm
'„ Displacement
State
Drive Torque Nm Dist mi
%Thrattle Turbine RPM
Motor Tonque Nm Wheel RPM
Drake Torque Nm Motor RPM
Brakes, Transmission &
Vehicle Dynamics
% Displacement F|OU|
Sys MPa
RPM MotorTorque Nm
Drive Motor
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
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As an initial test of the validity of the model, we compared the fuel economy modeling results
for the base conventional engine/transmission vehicles with actual fuel economy test data for
conventional vehicles obtained from the formal EPA fuel economy database. Appendix G shows
the data that was used for this comparison.
For a group of top-selling large SUVs, the sales-weighted average city/highway fuel economy
from EPA's federal fuel economy database (based on formal testing of prototype vehicles by
EPA and industry) is 14.5/21.3 mpg (combined value of 16.9 mpg), with a range of 12.8 to 15.4
mpg city and 19.1 to 22 mpg highway. Our model projected city/highway fuel economy, for a
representative large SUV with a 5.4-liter gasoline engine and conventional transmission, of
14.9/21.2 mpg (combined value of 17.2 mpg). For a group of top-selling midsize cars the sales-
weighted average city/highway fuel economy from the official EPA fuel economy database is
24.2/37.8 mpg (combined value of 28.9 mpg), with a range of 22.2 to 25.8 mpg city and 35.4 to
39.2 mpg highway. Our model projected city/highway fuel economy, for a representative
midsize car with a 3.0-liter engine and conventional transmission, of 24.3/37.9 mpg (combined
value of 29.0). SHERPA projections are within 3% of the average city, highway, and combined
city/highway test results for both large SUVs and midsize cars from the EPA fuel economy
database and so SHERPA is very good at predicting the fuel economy of vehicles with
conventional powertrains. Likewise, model results for some of the full hydraulic hybrid
configurations have also been compared to actual test data from EPA's full hydraulic hybrid
proof-of-concept test chassis with good correlation.
5.2 Example
To illustrate the fuel economy modeling process, the following is a briefcase study of the design
process and key design assumptions that were made for one of the 40 unique fuel economy
modeling scenarios-the large SUV with conventional gasoline engine and full hydraulic hybrid
drivetrain with engine-off strategy. The design parameters assumed for the engine, hydraulic
pump/motors, and hydraulic accumulators for this example powertrain configuration are
described below. It should be noted that for every technology package there are many
reasonable alternative assumptions that could be made. In this context, the assumptions and
results of the fuel economy modeling should be viewed as reasonable and plausible, but not
necessarily optimized. If any of these technology packages were to be commercialized, it is
likely that optimization would yield different, and most likely higher, fuel economy levels.
The design process begins with the selection of the engine and determination of the engine pump
capacity based on the engine operating strategy. Next the drive motor gearing and capacities are
chosen. Zero to sixty performance of the system is the modeled and compared with the baseline
performance. If necessary, the engine and/or pump/motors are reconfigured to obtain a vehicle
configuration of equal performance.
5.2.1 Engine
For the full hydraulic hybrid vehicle as modeled with stop/start engine operation, the basic
strategy is to run the engine at a high efficiency "minimum efficient power" or shut it off. There
are many possible variations on this theme, but this is one of the simplest. If the driver demands
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 56
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a higher power, then the engine will run along a line to a higher power point, but the engine will
never run below its minimum efficient power.
Frequent engine shutdown results, for the city cycle, in the engine being restarted 21 times and
the engine being on for 27% of the time. Over the highway cycle, the engine is restarted 9 times
and on for 79% of the time. The consumer acceptability of this amount of engine cycling is
unknown. In order to account for the fact that gasoline engines are more inefficient during
startup, we assessed a 2% absolute fuel economy penalty at the peak engine efficiency point (and
proportionally lower efficiency penalties at other points on the engine map). For the variable
displacement gasoline engine, a smaller fuel economy penalty was assumed since the engine is
on more often and the restart involves a smaller engine displacement.
Based on a 5.4-liter engine map, the peak engine efficiency is 33.5% at approximately 40 kW at
1500 RPM, which implies a torque of about 250 Nm. For start/stop engine operation, the higher
the minimum power the lower the total duty cycle and the shorter the average run time.
5.2.2 Hydraulic Pump/Motors
Based on experience with in-house proof-of-concept test chassis and looking at the torque
required at the minimum vehicle operating pressure, a 160 cc/rev engine hydraulic pump was
initially considered (but a smaller unit was ultimately selected for the modeling of this design, as
will be discussed below). For a minimum system pressure (high pressure minus low pressure) of
2000 PSI, a 160 cc/rev pump can absorb approximately 350 Nm of torque, which is more than
required to match the 250 Nm needed for the chosen operating point and allows absorption of
full engine power at minimum system pressure.
Next we must choose the size of the drive motor(s) and gear ratio(s). Again, we have a choice of
many configurations. For the purposes of this study we decided on a simple two-motor
arrangement. The secondary unit incorporates a one-way clutch and is only used for driving, not
regenerative braking. This is similar to an arrangement we have on an in-house test chassis. The
second unit may or may not incorporate a torque converter for low-speed launch and drives the
rear wheels for an all wheel drive configuration. For this configuration we assume a two-speed
planetary gearbox without torque converter between the rear pump/motor and the final drive.
The goal then is to size the primary unit to be able to provide most or all of the necessary drive
energy and to absorb all of the kinetic energy during regenerative braking.
For this chassis, a 110 cc/rev primary motor was chosen with a gearratio of 4.5:1. This is
similar to an arrangement we have on an in-house test chassis. Over the city cycle, this
combination provides 99.4% of the required drive energy. Over the highway cycle, this
configuration provides 100% of the required drive energy. The 4.5:1 ratio allows the use of full
pump displacement at 90 MPH and implies a maximum (RPM limited) speed of 121 MPH.
The secondary motor and gear ratio are sized for vehicle performance during acceleration with
the goal of matching the performance of the conventional vehicle. For this vehicle we chose a
110 cc/rev secondary motor with a 4.0:1 axle ratio and two-speed planetary with ratios of 3.5:1
and 1:1. For a starting system pressure of 3000 PSI this results in a modeled O-to-60 mph
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 57
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acceleration time of approximately 8.0 seconds, which is faster than the modeled base vehicle
acceleration time of about 8.8 seconds.
Since the common ground for all configurations is equal performance based on O-to-60 mph
acceleration time, the engine is downsized by 15% to a 4.6L engine. The new acceleration time
is then 8.9 seconds, which compares favorably to the baseline vehicle's acceleration time.
Downsizing the engine requires re-examining the choice of engine "sweet spot", which becomes
30 kW at 1500 RPM. The engine pump is also downsized, from the 160 cc/rev unit originally
considered, by the same percentage to 135 cc/rev.
It is important to emphasize that this configuration has the primary benefits of being simple and
low-cost, but has the corresponding drawback of not being as optimized for fuel economy as a
more complex configuration. Based on our in-house laboratory experience, we are confident that
a higher-cost design could yield significantly higher fuel economy values. EPA in fact is
working with industry partners to better identify the tradeoffs associated between simplicity and
cost, on the one hand, with fuel economy optimization.
5.2.3 Hydraulic Accumulators
The next major decision is the capacity of the two accumulators. The vehicle has one high-
pressure (roughly 2000 to 5000 PSI) accumulator to store energy and one low-pressure (roughly
100 to 300 PSI) accumulator to provide the necessary minimum inlet pressure to the hydraulic
units during pumping. For this vehicle a 15 gallon capacity (for each accumulator) was chosen.
It should be noted that this is larger than the 7 gallon capacity required for the mild hydraulic
hybrid configuration because the high-pressure accumulator must not only store energy from
regenerative braking but must also act as a buffer for the engine start/stop operation. A smaller
accumulator will result in more frequent, shorter engine runs and a larger accumulator will result
in less frequent, longer engine runs. As long as the accumulator can absorb the required
regenerative braking energy and provide some engine buffering, accumulator size makes little
difference to fuel economy (other than as a weight penalty) but has a large effect on the engine
operating characteristics.
These were the major assumptions involved with this particular technology package. A similar
approach, each with its own set of assumptions, was carried out for the other 39 fuel economy
modeling scenarios.
5.3 Results
EPA staff used the SHERPA model to project the fuel economy for the 40 different fuel
economy modeling scenarios shown in Table 4-3. The results of fuel economy modeling
exercise are shown in Table 5-1 in two different metrics.
The first fuel economy metric is simply the vehicle mpg value. For both the 4WD large SUV
and midsize car matrices, the top set of data gives the projected combined city/highway fuel
economy value for each of the various technology packages. For example, the 4WD large SUV
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with conventional gasoline engine and conventional transmission has a projected fuel economy
value of 17.2 mpg and the midsize car with conventional gasoline engine and conventional
transmission is projected to have a combined fuel economy of 29.0 mpg. These two technology
packages represent the baseline values for calculating the percent improvement of the other
vehicle technology packages.
Table 5-1: Fuel Economy Modeling Results
Large Sport Utility Vehicle
(4WD)
Fuel Economy (MPG) *
^
•^ r^
^ '•£? I ^ ^ i
/////A
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Fuel Economy Improvement (%)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
dean Diesel Variable Displacement Engine
Midsize Car
(2WD)
Fuel Economy (MPG) *
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Fuel Economy Improvement (%)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
dean Diesel Variable Displacement Engine
17.2
23.6
19.7
26.8
19.4 | 20.0
27.0 !
22.5 !
30.9 |
27.6
22.8
31.3
20.2 |
27.2 !
22.8 !
31.2 |
23.0
32.0
24.1
34.6
base
37%
15%
56%
13%
57%
31%
17%
61%
33%
80% ; 82%
18%
59%
33%
34%
86%
40%
82% ; 101%
29.0
39.8
35.4
46.9
32.4
48.5
40.7
57.5
! 34.1
! 50.2
I 42.0
I 59.3
36.0 !
50.0 |
44.1 I
58.7 I
43.5
59.9
45.4
64.3
base
37%
22%
62%
12%
67%
41%
99%
| 18%
: 73%
! 45%
! 105%
24% |
73% j
52% |
103% !
50%
107%
57%
122%
The second fuel economy metric in Table 5-1, shown in the bottom set of data for the 4WD large
SUV and midsize car classes, is the percent fuel economy improvement over the baseline
vehicles described above. Typically, the percent fuel economy improvement is the easiest way
to compare the relative fuel economy improvement potential of various technology packages.
As Table 5-1 shows, the 4WD large SUV conventional gasoline engine and full hydraulic hybrid
drivetrain with engine-off strategy is projected to be 34% more efficient than the base SUV,
raising the large SUV fuel economy from 17.2 mpg to 23.0 mpg. As discussed earlier, the
specific design of this configuration was optimized for simplicity and low cost, rather than
maximum fuel economy, and this value could be significantly higher if the design were
optimized for maximum fuel economy. For the full range of vehicle technology packages, fuel
economy is projected to improve by from 13-101% for the 4WD large SUV, and from 12-122%
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for the midsize car. It should be noted that rounding can sometimes lead to some slight
differences between the values in tables such as Table 5-1 and some of the spreadsheet values
shown in the appendices as well as some of the sample calculations.
Several trends are apparent from Table 5-1:
> the single change of replacing a conventional gasoline engine with a clean diesel engine
is projected to increase fuel economy by 37% for both 4WD large SUVs and midsize cars
> the single change of replacing a conventional gasoline engine with a variable
displacement engine is projected to increase fuel economy by 15-22%
> changing from a conventional engine to an engine with the dual characteristics of clean
diesel and variable displacement is projected to increase fuel economy by 56-62%
> the single change of adding a mild hydraulic hybrid drivetrain is projected to increase
fuel economy by 12% (midsize car with engine-on strategy) to 18% (midsize car with
engine-off strategy)
> the single change of moving to a full hydraulic hybrid vehicle is projected to increase fuel
economy by 18% (4WD large SUV with engine-on strategy) to 50% (midsize car with
engine-off strategy)
> the mild hydraulic hybrid drivetrain with engine-on strategy, the mild hydraulic hybrid
drivetrain with engine-off strategy, and the full hydraulic hybrid drivetrain with engine-
on strategy all yield fairly similar fuel economy improvements; the full hydraulic hybrid
drivetrain with engine-off strategy gives the highest fuel economy improvements for any
of the hydraulic-only drivetrains
> there is a relatively small fuel economy benefit of adding a variable displacement engine
to a vehicle that has a full hydraulic hybrid drivetrain with engine-off strategy (there
would be additional benefits associated with reduced engine on/off and off/on cycling
and a less costly accessory drive system)
> the maximum improvement for the 4WD large SUV is a 101% improvement for the
technology package involving an engine with both clean diesel and variable displacement
and a full hydraulic hybrid drivetrain with engine-off strategy
> the maximum improvement for the midsize car is a 122% improvement for the
technology package involving an engine with both clean diesel and variable displacement
and a full hydraulic hybrid drivetrain with engine-off strategy
The table in Appendix H reports the fuel economy modeling results for the city and highway test
cycles separately, which is of particular interest for hydraulic hybrid drivetrains which typically
achieve much greater fuel economy improvement in city driving.
Comparisons can be made between these modeling results and the literature for 5 of the 40
technology scenarios: the baseline conventional gasoline engine and conventional transmission
for both large SUVs and midsize cars, the clean diesel engine for both large SUVs and midsize
cars, and the mild hydraulic drivetrain with engine-on strategy for large SUVs. As discussed
earlier in this section, the model results for the combined city/highway fuel economy values for
the baseline large SUV and midsize car of 17.2 and 29.0 mpg, respectively, compare favorably
with the sales-weighted values of 16.9 and 28.9 mpg that were calculated for large SUVs and
midsize cars from the formal EPA fuel economy certification data base. The projected fuel
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 60
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economy improvements for clean diesel engines of 37% for both large SUVs and midsize cars
are in line with industry statements that diesel vehicles are typically 30-40% more fuel efficient
than comparable gasoline vehicles.x" xm Finally, Ford Motor Company has reported a 24% fuel
economy improvement over the EPA city driving cycle for a large SUV with a conventional
gasoline engine and a mild hydraulic drivetrain with engine-on strategy.X1V This compares well
with the model projection of a 26% improvement for this same configuration (see Appendix H
for the separate urban and highway fuel economy projections).
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 61
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6. Projection of Incremental Vehicle Cost
6.1 Overview
This section projects the cost increases that would likely be associated with the vehicle
technology packages, identified in Section 4 and modeled for fuel economy impacts in Section 5.
It is very important to emphasize the underlying assumptions involved in the cost projections.
The central assumption is that the cost projections are for a longer-term scenario where the
economies of scale (component production volumes of one million units per year) and relative
profit for the advanced technology vehicles approach those for high-volume conventional
vehicles today. The rationale for this assumption is threefold: 1) it allows an "apples and
apples" comparison with conventional technology, 2) a valid long-term business case is a
critical parameter for justifying investment in a new technology, and 3) it is consistent with the
cost assumptions in most other technology studies. These cost projections are not relevant to a
transition period where the advanced technology is initially commercialized (and annual
component production volumes might only be in the thousands or tens of thousands). During a
transition period, there will be many relevant cost factors that will be nonexistent or negligible in
a mature market, including but not limited to: recovery of research and development
expenditures; initial investment in component manufacturing facilities, vehicle assembly plants,
and dealer and maintenance infrastructure; engineering time for vehicle design modifications to
accommodate the new technology; and higher per unit costs due to lower economies of scale.
Accordingly, the transition costs would be higher than the long-term cost projections for the
advanced technologies in this study. On the other hand, it is also a basic tenet of automotive
production that, once a technology achieves market maturity, there is overwhelming economic
incentive to continue to invest in research to continually reduce cost. So it is also likely that the
cost projections in this report underestimate the potential to reduce cost if and when any of these
advanced technologies actually achieve market maturity. The bottom line is that the cost
projections in this study are most relevant to a period 5-10 years beyond initial
commercialization when economies of scale first reach high levels.
For the advanced engine technologies (clean diesel engines and variable displacement engines),
we rely on cost analyses and projections provided by FEV Engine Technology, Inc., a major
engine design and consulting company headquartered in Germany and with a US office in
Auburn Hills, Michigan. For diesel engine emission control systems, we rely on projections
from EPA engineers involved in our in-house technology assessment program. For the advanced
drivetrain technologies (mild hydraulic hybrids and full hydraulic hybrids), we use system
designs from EPA engineers who have been leaders in hydraulic hybrid research and
development for the last decade, and we utilize a methodology based on changes in component
mass and complexity relative to baseline vehicles. For vehicle technology packages that involve
both engine and drivetrain changes, we combine the projections from FEV and EPA engineers.
6.2 Clean Diesel Engines
FEV was contracted to project the incremental cost of a diesel engine compared to a
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 62
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conventional gasoline engine for this study. The three most important assumptions underlying
FEV's analysis were:
> the analysis only included changes directly and indirectly associated with the engine and
did not, for example, include any potential incremental costs associated with diesel
emissions aftertreatment
> the analysis assumed a mature diesel engine production environment where there are
equal economies of scale for diesel engines and gasoline engines, and where the relative
profit from diesel engines are equal to that from gasoline engines
> the diesel and gasoline vehicles are designed to have equal performance in general, and
equal O-to-60 mph acceleration times and equal vehicle ranges in particular
FEV's cost estimates for a clean diesel engine are described in the report Cost and Fuel Economy
Comparison of Diesel and Gasoline Powertrains in Passenger Cars and Light Trucks (see
Appendix I). For both the large SUV and the midsize car, the primary incremental costs
associated with the diesel engine are due to high-pressure common rail fuel injection and a
variable geometry turbocharger. As shown in Table 10 of Appendix I, FEV projected the
incremental cost of the fuel injection system for a large SUV to be $735. (Taking into account a
projected gasoline SUV fuel injection system cost of $245, FEV projects a total diesel fuel
injection cost of $980 for a large SUV. Similarly, adding a gasoline midsize car fuel injection
cost of $165 to the $465 shown in Table 9 of Appendix yields a total diesel fuel injection cost of
$630 for a midsize car.) FEV estimated the mature incremental manufacturing costs of a clean
diesel engine to be $1042 for a large SUV and $739 for a midsize car.
It is generally accepted that, based on current state-of-the-art engine technologies, emissions
control systems for diesel vehicles to meet Tier 2 emission levels will be more expensive than
those for comparable gasoline vehicles. There is a major industry effort underway to develop
viable and cost-effective diesel engine emission control systems, and it is impossible at this time
to project the likely cost impacts of such systems with any precision. Nevertheless, based on the
best information regarding emission control technology at this time, EPA engineers provided
projections of this incremental cost: $282 for large SUVs and $218 for midsize cars. EPA
assumes that there would be no fuel economy penalty associated with diesel emissions control
systems. EPA is monitoring progress in this area and will modify these projections as more
information becomes available.
An aggregate incremental retail cost to the consumer will include the incremental engine cost
plus the incremental emissions control cost plus a retail markup factor. In regulatory
development, EPA uses a retail price equivalent (RPE) mark-up factor of 1.26 to adjust a
manufacturing price increase to a retail price increase. This factor accounts for manufacturer
overhead and profit. The total incremental retail cost to the consumer for a large SUV, assuming
no change in fuel tank size, is the $1042 incremental engine cost plus the $282 incremental
emissions control cost, times the 1.26 markup factor, or a total of $1668. The total incremental
retail cost to the consumer for a midsize car, assuming no change in fuel tank size, is the $739
incremental engine cost plus the $218 incremental emissions control cost, times the 1.26 markup
factor, or a total of $1206.
6.3 Variable Displacement Engines
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FEV was also contracted to project the incremental cost of a variable displacement engine
compared to a conventional gasoline engine for this study. The key underlying assumption in
this analysis was that there would be no other changes in engine design or performance other
than those necessary to allow the engine to operate as a variable displacement engine.
FEV estimated the incremental manufacturing cost of a 5.0-liter, V-8 variable displacement
engine, relative to a conventional gasoline engine of the same displacement, in the report
Variable Compression Ratio and Variable Displacement Engine Cost (see Appendix J). For
conventional drivetrains, FEV estimated the mature incremental manufacturing cost of the 5.0-
liter variable displacement engine to be $431 ($278 for incremental changes to the engine itself
plus an additional $153 due to the more complex control system plus associated parts). This
estimate for a 5.0-liter, V-8 engine is assumed to be applicable to the slightly larger 5.4-liter, V-8
engine used for the large SUV scenario in this report. Applying the EPA RPE markup of 1.26 to
FEV's projected incremental manufacturing cost for a variable displacement engine yields
incremental consumer costs of $543 for a large SUV with no change in fuel tank size. Adjusting
fuel tank size for equivalent range, the total incremental cost of a variable displacement engine in
a large SUV with a conventional transmission drops by $11 to $532. For hydraulic drivetrains,
where two intermediate bearing assemblies could be deleted, the FEV estimate is $406 for the
manufacturing cost of a variable displacement engine for a large SUV. The retail price
equivalent for the variable displacement engine only in combination with the hydraulic drivetrain
for a large SUV is $512.
FEV did not project the cost of a variable displacement engine for the midsize car scenario. EPA
calculated a projected cost for a 3.0-liter, V-6 variable displacement engine based on the FEV
projection for the 5.0-liter, V-8 engine discussed above. EPA assumed that most of the
incremental costs for modifying a conventional engine to be a variable displacement engine
would be proportional to engine weight, but that certain costs (e.g., control system plus
associated parts) would remain the same regardless of displacement. One additional issue with a
variable displacement V-6 engine is whether a balance shaft or some other modification will be
necessary for NVH reasons, particularly vibration. In fact, it may be possible that variable
compression is a preferred engine design for a midsize car application, and FEV projected a
lower incremental cost for a variable compression car engine than for a variable displacement car
engine. Nevertheless, assuming a variable displacement engine without a balance shaft, EPA
calculated a projected incremental manufacturing cost of $340 for a 3.0-liter, V-6 engine for the
midsize car scenario. Applying the 1.26 retail price equivalent markup factor yields a consumer
cost of $428 assuming equal fuel tank size. Adjusting fuel tank size for equivalent range yields
a total incremental cost for a variable displacement engine in a midsize car with a conventional
transmission of $412. The consumer cost for a variable displacement engine only in
combination with a hydraulic hybrid drivetrain is again slightly lower, or $396.
6.4 Hydraulic Hybrid Drivetrains
For hydraulic hybrid drivetrains, EPA employed a simple first order cost methodology that was
patterned after what we were able to project as the estimated cost of similar vehicle chassis,
engine and transmission components. Others have employed similar cost methodologies that are
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somewhat more detailed. These analyses specifically breakout individual component
manufacturing costs and then try to identify and apply the appropriate overhead, profit and mark-
up costs (such as in the EPRI study - Comparing the Benefits and Impacts of Hybrid Electric
Vehicle Options, July 2001). However, since we did not have access to proprietary data for
overhead, profit and markup (as adjusted for COLA, manufacturing improvements and current
material costs), we projected component system cost values for three vehicle subsystems
(transmission, engine, and chassis) using detailed vehicle cost data from a typical 1990 Big-
Three vehicle scaled to 2002 retail costs. These component costs were then adjusted to retail
price by applying the same retail price equivalent (RPE) factor, 1.26, that we use when
implementing new emission regulations. The RPE factor accounts for manufacturer overhead
and profit. While a more rigorous analysis may give more "precise" costs for individual
components, we felt that when aggregated together this method would work well to show the
magnitude of the incremental cost changes.
The key input for the EPA cost projections is the detailed description of the hydraulic hybrid
drivetrains in Section 3. That section described in considerable detail plausible designs for four
hydraulic hybrid configurations: full hydraulic hybrid 4WD SUV, mild hydraulic hybrid 4WD
SUV, full hydraulic hybrid car, and mild hydraulic hybrid car. Specifically, for each of these
hydraulic hybrid configurations, Section 3 provided a comprehensive list of every component
that would be added to the baseline vehicle and every component that could be deleted from the
baseline vehicle, as well as the mass for each of these components.
It is important to emphasize that, particularly for a 4WD large SUV with full hydraulic hybrid
drivetrain, several components can be deleted from the conventional vehicle (most notably the
automatic transmission and transfer case), which greatly reduces the incremental cost that would
otherwise be associated with a hydraulic drivetrain.
The individual mass values for each of these components, both those added to and those deleted
from the baseline vehicles, provides the starting point for the cost analysis in this section. The
supplier price of each component is estimated from the weight of the component multiplied by
price per unit of weight. The price per unit weight varies depending on the complexity of the
component. There are three major price per weight figures used in this analysis, based on
components that are used in three major vehicle subsystems: transmission, engine, and chassis.
For some components that are not in a conventional vehicle, such as a hydraulic pump/motor, we
examined the overall manufacturing complexity, the material composition, and the design in
order to group this component in one of the three major vehicle subsystems. For example, the
hydraulic pump/motors are made primarily of cast iron and steel, with some bronze and
aluminum components. The manufacturing complexity for a pump/motor, which contains
pistons, connecting rods, cylinder bores, rotating shafts, roller and bronze bearings, and
electronic components and sensors associated with displacement and mode control, is similar to
the complexity found in automotive engines. Therefore, we used the engine price per weight
factor for estimating the cost of the hydraulic pump/motors.
Specific price per weight values for these three vehicle subsystems (transmission, engine, and
chassis) were derived using cost data from a typical 1990 Big-Three vehicle adjusted to 2002
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costs [vehicle configuration specs: 3. OL, V6, 4-speed automatic, fuel injected, front wheel drive].
Appendix K shows the original cost by component for the 1990 vehicle. The cost and weights
for the three component systems of interest were taken from Appendix K and are provided below
in the first two columns of Table 6-1. The 1990 costs were adjusted to a 2002 model year
vehicle by multiplying by the ratio of 1990 to 2002 Manufacturer's Suggested Retail Price
(MSRP). The sample vehicle's MSRP is $12,944 while a 2002 version of that model has an
estimated MSRP of $20,000. The resulting price per kg by component system for a current
vehicle is listed in the last column of Table 6-1. The complexity category based on transmission
components is the most complex, with a price of $10.45 per kg, the category based on engine
components uses a value of $9.11 per kg, and the category based on chassis components is the
least complex at a price of $7.19 per kg.
Table 6-1: Price per Weight ($/kg)
Component System
Total Transmission
Total Engine
Total Chassis
Weight
kg
64
274
527
1990
Manufacturer Cost
$431
$1616
$2453
2002
Manufacturer Cost
$666
$2497
$3790
$/kg
$10.45
$9.11
$7.19
For each of the hydraulic hybrid drivetrains, most of the components (whether added to or
deleted from the baseline vehicle) were grouped into one of these three "complexity categories"
based on the three price per mass factors above. However, a few components such as hydraulic
accumulators and various fluids were considered unique enough that separate cost projections are
developed. The prices per kg of hydraulic and transmission fluids are based on publicly
available cost information. EPA engineers who are experienced in the design and development
of hydraulic systems provided the price per kg for accumulators. The accumulator costs assume
high volume production and are optimized for lighter materials as discussed in Section 3.
All components, both those added to and those deleted from baseline vehicles, were grouped into
the three main complexity categories based on engineering judgment. The changes in mass were
then multiplied times the price per unit mass for each component added or deleted from the
baseline vehicle, allowing a total incremental cost projection for each of the cost scenarios.
6.5 Adjustment in Fuel Tank Size
As was shown in Table 5.1, all of the vehicle technology packages in this study have fuel
economy values higher than the base large SUV and base midsize car equipped with
conventional gasoline engines and conventional mechanical transmissions. Therefore, if fuel
tank size were held constant for the large SUV and midsize car scenarios with advanced vehicle
technologies, all of the advanced technology vehicles would have higher vehicle range (miles
that can be driven on a full tank of fuel). Designs were chosen that would have comparable
vehicle range, so the fuel tank could be somewhat smaller. The reduction in fuel tank size and
weight was calculated as proportional to the increase in projected fuel economy for each vehicle
technology package. Since fuel tanks are a very small fraction of a vehicle's total weight, the
resulting cost benefits were small.
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6.6 Example
The cost modeling example focuses on the same technology package used previously in Section
5—the 4WD large SUV with conventional gasoline engine and full hydraulic hybrid drivetrain
with engine off strategy.
Table 3-8 lists all of the components that would be added to and removed from a baseline 4WD
large SUV in order to transform the design into a 4WD large SUV with conventional gasoline
engine and full hydraulic hybrid drivetrain with engine-off strategy. The major additions are:
> 3 pump motors (one 135 cc unit and two 110 cc units) - engine, front axle, rear axle
> 2 accumulators (each 15 gallons) - high pressure, low pressure
> a 2-speed planetary gearbox
> all of the fluids, fittings, hoses, etc. in the hydraulic circuit
The major component deletions for the 4WD large SUV are:
> conventional transmission
> transfer case
> downsized engine
The calculation of the cost of the 135 cc pump motor unit is illustrated below. The pump motor
has a mass of 45.7 kg. Pump motors are considered to be similar to engines in terms of the
complexity of manufacturing. Therefore, $9.11 is used as the price per kg for a pump motor.
The supplier or manufacturing price of the pump motors is calculated as:
Supplier's Price = 45.7 kg * $ 9.11 per kg = $ 416
A similar process is followed for all the components listed in Table 3-8 for the 4WD SUV's full
hydraulic hybrid drivetrain. Table 6-2 gives the total supplier price for the removed and added
components. The total supplier's price is then multiplied by the RPE factor. Based upon this
method of calculation, the total retail cost increment of the hydraulic hybrid components is $575
($3,352 for the additional hybrid components minus $2777 for the conventional transmission that
is deleted).
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 67
-------
Table 6-2: Incremental Costs for Large 4WD SUV with Full Hydraulic Hybrid
Drivetrain and Engine-Off Strategy
Component
Complexity Level #1 (like a Transmission)
automatic transmission
transfer case
2 speed planetary (w/housing) for rear power unit
Complexity Level #2 (like an Engine)
engine downsize
power steering system (pump, reservior, steering gear)
135 cc engine pump motor (w/ mounting flange and bearing)
1 10 cc pump motor (combined frt power unit saves 8 kg est.)
1 10 cc motor for rear power unit
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
rear drive shaft
front drive shaft
transmission cooler and lines
fitting and hoses
accumulator mounting brackets
oil cooler and filter loop (front motor low side) + mount
engine/PM coupling and fasteners
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
15 gal composite accumulator (high pressure)
15 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-106.0
-47.3
15.0
-31.0
-17.3
45.7
29.2
37.2
15.6
4.5
-2.4
-9.8
-7.3
-1.8
33.3
6.0
9.5
5.3
-11.8
38.8
56.0
23.4
84.8
Price Factor
($ per kg)
$10.45
$10.45
$10.45
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$1,108
-$494
$157
-$282
-$158
$416
$266
$339
$142
$41
-$17
-$70
-$52
-$13
$239
$43
$68
$38
-$9
$116
$560
$234
$457
$575
Calculation of fuel tank downsize (included above)
fuel efficiency improvement 31.6%
base mpg 14.63
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page 68
-------
6.7 Results
Table 6-3 provides a summary of the incremental new vehicle costs for the 38 new
technology scenarios along with the cost per percent fuel economy improvement, a metric often
used in the industry.
Table 6-3: Incremental New Vehicle Costs
Large Sport Utility Vehicle
(4WD)
New Vehicle Cost Increase ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cosf Increase / FE Improvement ($ per %)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Midsize Car
(2WD)
New Vehicle Cost Increase ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cosf Increase / FE Improvement ($ per %)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
,$•• vj; i ^ \
3?-£> / •$?•&
A* / <«
base
$1,668
$532
$2,195
$1,321
$2,983
$1,822
$3,487
I $1,336
I $2,999
j $1,838
! $3,504
$552 I
$2,217 I
$1,055 j_
$2,721 |
$575
$2,241
$1,084
$2,749
base
$45
$36
$39
$100 !
$52 i
$59 I
$44 |
$81
$49
$56
$43
$32 !
$38 i
$32 I
$33 |
$17
$26
$27
$27
base
$1,206
$412
$1,613
$998
$2,182
$1,373
$2,567
I $1,009
I $2,195
| $1,386
; $2,581
$1,114 I
$2,307 |
$1,493 j
$2,692 ;
$1,133
$2,330
$1,525
$2,722
base
$32
$19
$26
$83
$32
$34
$26
! $57
_\ $30
I $31
j $25
$46 !
$32 |_
$28 I
$26 j
$23
$22
$27
$22
Several key trends from Table 6-3 are:
> the lowest-cost advanced technology packages involve either the single change of
replacing a conventional gasoline engine with a variable displacement engine in either the
4WD large SUV or midsize car, or the single change of replacing the conventional
transmission of a 4WD large SUV with a full hydraulic hybrid drivetrain (either engine-
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page 69
-------
on or engine-off strategy), all of which have incremental costs between $412-$575
> the single change of replacing a conventional gasoline engine with a clean diesel engine
is projected to cost $1206 (midsize cars) to $1668 (large SUVs)
> changing from a conventional engine to an engine with the dual characteristics of clean
diesel and variable displacement is projected to increase cost by $1613 (midsize cars) to
$2195 (large SUVs)
> the single change of adding a mild hydraulic hybrid drivetrain is projected to increase
cost by approximately $1000 (midsize car) to $1300 (large SUV)
> the single change of moving to a full hydraulic hybrid is projected to increase new
vehicle cost by from about $600 (4WD large SUV) to $1100 (midsize car); the reason
the incremental cost is less for the larger vehicle is that much more expensive
components can be deleted from the 4WD large SUV baseline vehicle with the addition
of a full hydraulic hybrid design
> for 4WD large SUVs, the full hydraulic hybrid package always has a lower incremental
cost than the mild hydraulic package, again because more expensive components can be
deleted; on the other hand, for midsize cars, the full hydraulic package is always slightly
more expensive than the mild hydraulic hybrid package
> the highest-cost advanced technology package for the 4WD large SUV is the clean diesel
with variable displacement engine and mild hydraulic hybrid drivetrain, with an
incremental cost of approximately $3500; the highest-cost advanced technology package
for the midsize car is the clean diesel with variable displacement engine and full
hydraulic hybrid drivetrain, with an incremental cost of about $2700
> the cost per percent fuel economy improvement ranges from $17 (4WD large SUV with
conventional gasoline engine and full hydraulic hybrid drivetrain with engine-off
strategy) to $100 (4WD large SUV with conventional gasoline engine and mild hydraulic
hybrid drivetrain with engine-on strategy)
Appendix L contains the full spreadsheets for each of the 38 new technology cost scenarios.
Some of the values in the body of the report will differ slightly from values in the spreadsheets
due to rounding.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 70
-------
7. Projection of Payback Period and Lifetime Savings
7.1 Overview
Payback refers to the number of years that it takes for one or more consumers to offset in
operating savings the extra cost that they paid for the new technology when they bought the
vehicle. Lifetime savings is the total net savings in dollars (total operating savings minus higher
initial new vehicle cost) that consumers will realize over the typical lifetime of a vehicle. The
operating savings associated with the advanced technology powertrains in this study are
primarily fuel savings due to higher vehicle fuel economy, plus brake maintenance savings with
hydraulic hybrid drivetrains (there may be other operating costs and/or savings associated with
advanced technologies, but no others are included here). The calculation of both consumer
payback and lifetime savings are relatively straightforward, and relies heavily on the results of
the fuel economy modeling and the cost projections discussed previously. While these
calculations require spreadsheet calculations, they do not require sophisticated modeling.
Two of the key inputs into the calculation of consumer payback and lifetime savings are the fuel
economy of the base vehicle without the new fuel economy technology and the fuel economy of
the vehicle with the new fuel economy technology. The projected fuel economies for all the
vehicle technology packages, in mpg, are shown in Table 5-1 (the values in Table 5-1 are
unadjusted fuel economy values, and are adjusted downward by about 15% for purposes of the
payback analysis in this section to account for laboratory-to-road shortfall, to better reflect the
fuel economy that a consumer would achieve in the real world).
A third input is a profile of miles traveled per year as consumer payback with a fuel economy
technology will be much quicker and lifetime savings will be greater for a consumer that drives
high annual mileage than for a consumer that drives low annual mileage. For the midsize car
scenario, this analysis uses the official annual miles traveled profile for cars from EPA's
MOBILE6 emissions model used for motor vehicle emission regulation and air quality analyses.
This profile projects that the typical car travels about 14,900 miles in its first full year of
operation and then travels fewer miles in each succeeding year, falling to 12,200 miles in the
fifth year, 9500 miles in the tenth year, and 7700 miles in year 14. For the large SUV scenario,
this analysis uses the MOBILE6 profile for light-duty trucks, which projects about 20,000 miles
for the first year of operation, dropping to 15,300 miles in the fifth year, 11,000 miles in the tenth
year of operation, and 8400 miles in the 14th year.
A fourth input is fuel price, as payback will be quicker and lifetime savings will be greater at a
higher fuel price than at a lower price. Predicting future fuel prices is, of course, a difficult task.
Just in the last three years, consumers in many parts of the country have paid as little as $1.00
per gallon and as much as $2.00 per gallon for gasoline. As this report is being written, average
nationwide gasoline price is approximately $1.50 per gallon. Diesel fuel is typically somewhat
cheaper than gasoline. This paper uses a flat $1.50 per gallon for both gasoline and diesel fuel.
Obviously, lower future fuel prices would raise the payback periods and decrease lifetime
savings and higher future fuel prices would lower the payback periods and increase lifetime
savings.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 71
-------
A fifth input is an appropriate discount rate. The rationale for use of a discount rate is that a
dollar is worth more to a consumer today than it will be to a consumer tomorrow. Since a
consumer will pay the extra cost associated with new fuel economy technology at the time of
vehicle purchase, but will only benefit from fuel and/or brake savings over time, use of a
discount rate in the calculations of payback and lifetime savings is appropriate. For this analysis,
EPA uses the 7% annual discount rate that is recommended by the Office of Management and
Budget (OMB) for monetary costs and savings associated with motor vehicle emissions
regulations. Based on OMB guidance, savings in the first year of vehicle operation are not
discounted. The savings in the second year are reduced by 7%, the savings in the third year are
reduced by approximately 14%, etc.
The final inputs, which are relevant only for hydraulic hybrid powertrains, relate to the frequency
and cost of brake maintenance. Because hydraulic hybrid vehicles will utilize regenerative
braking for the majority of their braking, as opposed to friction braking on conventional vehicles,
owners of hydraulic hybrid vehicles will need far less brake maintenance. See Appendix M for a
detailed description of the methodology used to project brake savings. The key assumption is
that brake maintenance will be reduced by 70% for a vehicle with a hydraulic hybrid drivetrain.
A spreadsheet was developed that uses the above factors to calculate the annual discounted fuel
savings each year associated with each vehicle technology package. The "payback year" is then
the first year during which the cumulative, discounted operating savings exceeds the initial cost
increase associated with the fuel economy technology. Lifetime savings are the net savings over
the life of the vehicle, i.e., operating savings minus the higher initial vehicle cost.
7.2 Example
This section shows how the payback year and lifetime savings are calculated for the same case
study as used in previous sections: the 4WD large SUV with conventional gasoline engine and
full hydraulic hybrid drivetrain with engine-off strategy.
MOBILE6 projects that a truck travels 19,978 miles in its first year of operation. We assume
that 55% of this travel will entail city driving, or 10,988 miles. From Table H-l, a "base" 4WD
large SUV with conventional engine and conventional transmission is projected to have a
laboratory city fuel economy value of 14.9 mpg. This laboratory value must be reduced by 10%
to yield a real world city fuel economy value, so the 14.9 mpg yields a real world city fuel
economy value of 13.4 mpg. A typical consumer traveling 10,988 miles with a fuel economy of
13.4 mpg would consume 820 gallons of gasoline. The remaining 45% of miles, or 8990 miles,
is assumed to be highway driving. From Table H-l, the laboratory highway fuel economy value
for the base 4WD large SUV is 21.2 mpg. Reducing this highway value by 22% yields a real
world highway fuel economy value of 16.5 mpg. A typical consumer traveling 8990 miles with
a fuel economy of 16.5 mpg would consume 545 gallons of fuel. So, total city plus highway fuel
consumption in the first year would be 820 plus 545 gallons or 1365 gallons. At $1.50 per gallon
and no discounting in the first year, the consumer would have a total fuel cost of $2048. So, the
owner of a "base" 4WD large SUV would spend $2048 on fuel in the first year.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 72
-------
The same set of calculations for a large SUV with full hydraulic hybrid drivetrain and engine-off
strategy yields a first-year fuel consumption of 1040 gallons of gasoline in the first year. At
$1.50 per gallon and no discounting in the first year, the consumer would have a total fuel cost of
$1560.
The fuel savings due to the addition of the full hydraulic hybrid drivetrain with engine-off
strategy for a 4WD large SUV is the difference between the $2048 a consumer would spend with
the "base" vehicle and the $1560 the consumer would spend with the full hydraulic hybrid
drivetrain with engine off. This difference is $488 for the first year of operation. This value is
slightly different than the $492 value shown in the spreadsheet table in Appendix N due to
rounding.
Table 6-3 shows that the incremental cost of the conventional gasoline engine and full hydraulic
hybrid drivetrain with engine-off strategy for the 4WD large SUV is $575. Carrying out the
same calculations above for the second year shows that the owner of a 4WD large SUV would
accrue cumulative fuel savings of $575 sometime during the third month of the second year, and
therefore would achieve consumer payback in 1.2 years.
Since payback was achieved after just 1.2 years in this example, prior to the time when any brake
savings would be realized, there was no need to take brake maintenance into account for this
payback calculation.
This is the only one of the advanced technology packages that offers payback as early as during
the second year. For each of the other cases, the discounted fuel savings and brake savings, if
any, are calculated for each succeeding year, added to the savings of the previous years, and
compared to the incremental cost until such time that the cumulative discounted operating
savings exceed the incremental cost, and that is the "payback year."
For the calculation of lifetime savings, we must sum lifetime fuel savings, lifetime brake savings
(if any), and higher vehicle cost. For the 4WD large SUV with full hydraulic hybrid and engine
off strategy, we show above that the first-year fuel savings would be $488. The fuel savings for
each succeeding year is smaller and smaller, both because the annual vehicle miles traveled is
less each year and because future savings are discounted by 7% per year. For example, the
discounted fuel savings for this 4WD large SUV with a full hydraulic hybrid drivetrain with
engine-off strategy drops to just $86 in the fourteenth year, the last year in our analysis. For the
14 years, the owner(s) of such a vehicle would save $3319 in discounted fuel savings.
Because of the full hydraulic hybrid drivetrain, brake wear would be reduced by approximately
70%. This means that pads and rotors will need less frequent service. For a typical large SUV,
this means less brake maintenance at four different times over its lifetime. Based on the
methodology in Appendix M, the sum of these discounted brake savings for a 4WD large SUV
with a full hydraulic hybrid drivetrain is $783. Total operating savings is the $3319 in
discounted fuel savings plus the $783 in discounted brake savings, or a total of $4102. The
lifetime savings is this $4102 in operating savings minus the $575 in higher vehicle cost, or
$3527.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 73
-------
7.3 Results
Table 7-1 shows the payback year and lifetime savings for the 38 new technology scenarios. The
units for payback are years, the units for lifetime savings are dollars.
Table 7-1: Projected Payback Years and Lifetime Savings
Large Sport Utility Vehicle
(4WD) '
Cost Payback to Consumers) (Years)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Net Lifetime Savings to Consumers) ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Midsize Car
(2WD)
Cost Payback to Consumers) (Years)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Net Lifetime Savings to Consumers) ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
base
3.6
2.3
3.5
4.9
4.6
4.2
4.5
I 4.4
I 4.5
i 4.1
i 4.5
2.0 |
3.2 |
2.1 j
3.3 |
1.2
2.5
2.0
2.9
base
$2,060
$1,175
$2,738
$955
$2,733
$2,067
$3,318
! $1,282
I $2,880
I $2,202
| $3,401
$2,159 !
$3,559 I
$2,975 I
$4,145 |
$3,527
$4,786
$3,472
$4,852
^£\4>£>
/////.
///*/#/
base
6.7
2.9
6.2
9.6
6.9
6.0
6.7
I 6.5
I 6.5
| 6.0
; 6.5
6.1 |
7-1 I
6.0 |
7.1 ;
4.2
6.0
5.8
6.4
base
$583
$756
$895
$70
$817
$862
$1,045
! $320
I $933
I $982
i $1,129
$525
$808
$1,101
$986
! $1,381
I $1,403
I $1,182
i $1,231
Some key trends from Table 7-1 are:
> The best payback is 1.2 years for the 4WD large SUV with a conventional gasoline
engine and full hydraulic hybrid drivetrain with engine-off strategy; the worst payback is
nearly 10 years for the midsize car with conventional gasoline engine and mild hydraulic
hybrid drivetrain with engine-on strategy
> the maximum lifetime savings are nearly $5000 for those 4WD large SUV packages with
both clean diesel engines and full hydraulic hybrid drivetrains with engine-off strategies
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page 74
-------
> for every technology package, the 4WD large SUV has a lower payback period and
higher lifetime savings than the midsize car
> all of the 4WD large SUV technology packages payback in 1-4 years, except for those
large SUV packages with mild hydraulic hybrid drivetrains, and these latter all have
paybacks of 4-5 years; every 4WD large SUV package yields lifetime savings of at least
$900 and many large SUV packages yield lifetime savings of $3000 or more
> the best payback for the midsize car is 2.9 years for the variable displacement engine with
conventional transmission; nearly all of the other midsize car packages payback in 4-7
years; most of the midsize car packages provide lifetime savings of $500-1400
Appendix N gives the spreadsheets with the data underlying the results shown in Table 7-1.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 75
-------
End Notes - References
1 Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards, National
Research Council, 2002.
11 Eaton Corporation Unveils Breakthrough Fuel Savings Technology at 2002 North American
International Auto Show, Eaton Corporation Press Release, January 7, 2002.
111 Clean Diesels Dispel Outdated 'Dirty' Image, General Motors website at www.gm.com, July
30, 2002.
1V Diesel Finds Liberty in North America, Automotive Engineering Magazine, January 2003.
v Testing of the Toyota Avensis DPNR at U.S. EPA-NVFEL, Joseph McDonald and Byron
Bunker, U.S. EPA , Society of Automotive Engineers Paper 2002-01-2877.
V1 Assessing New Diesel Technologies, presentation by Charles L. Gray, Jr., U.S. Environmental
Protection Agency, at MIT Light Duty Diesel Workshop, November 20, 2002.
vu GM's 'Displacement on Demand' V8 Engine Improves Truck Fuel Economy, General Motors
website at www.gm.com, July 30, 2002.
vm Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards, National
Research Council, 2002.
1X Saab Reveals Unique Engine Concept That Offers High Performance and Low Fuel
Consumption, Saab website at www.saabnet.com, March 2000.
x Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards, National
Research Council, 2002.
xi An HCCI Engine: Power Plant for a Hybrid Vehicle, R.Sun, R. Thomas and C. Gray, Jr., U.S.
Environmental Protection Agency, Society of Automotive Engineers Paper 2004-01-0933 (to be
released at the SAE Congress in March 2004).
xu Clean Diesels Dispel Outdated 'Dirty' Image, General Motors website at www.gm.com, July
30, 2002.
xm Diesel Finds Liberty in North America, Automotive Engineering Magazine, January 2003.
X1V Hydraulic Power Assist - A Demonstration of Hydraulic Hybrid Vehicle Regenerative
Braking in a Road Vehicle Application, R.P. Kepner, Ford Motor Company, Society of
Automotive Engineers Paper 2002-01-3128.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 76
-------
APPENDICES
Appendices
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 77
-------
APPENDIX A
Appendix A: Sensitivity Analysis with Reduced Roadload
Scenarios
A number of factors contribute to the overall energy demand of a vehicle. The three most
important parameters are the weight of the vehicle, the aerodynamic drag of the vehicle, and the
tire rolling resistance. Vehicle weight is an overt variable in the modeling discussed throughout
this report, and unique vehicle weights were projected and utilized for each of the vehicle
technology packages. Vehicle aerodynamic drag and tire rolling resistance are the other two
major factors in the roadload force equation, which gives the amount offeree required to propel
a vehicle as a function of vehicle speed. All of the results in the body of this report assume "base
roadload" values representing today's top-selling production vehicles. This Appendix presents a
sensitivity analysis for "reduced roadload" where projections for each of the 40 vehicle
technology scenarios are made assuming that roadload values are approximately 20% lower than
today's production levels.
The base roadload case was defined in Section 5 as the sales-weighted average roadload
specifications for today's top-selling vehicles in the large SUV and midsize car classes. The
automobile manufacturers supplied the base roadload equations to EPA as part of the submission
for the 2002 vehicle emissions certification program. For the reduced roadload case, the base
roadload specifications were lowered by 20%.
The cost of a 20% reduction in the roadload specifications was approximated by using a cost
estimate for the reduction in both vehicle coefficient of drag and tire rolling resistance by the
National Academy of Sciences/National Research Council (NAS/NRC). In Effectiveness of
Corporate Average Fuel Economy (CAFE) Standards, the NAS/NRC estimated an average cost
of $105 to reduce both coefficient of drag and tire rolling resistance by 10% (this cost already
included NAS' retail price equivalent markup factor and no further adjustment was made for this
analysis).2 This estimate was doubled to $210 for this sensitivity analysis to approximate the
costs of a nominal 20% reduction in aerodynamic drag and rolling resistance.
Tables A-l and A-2 provide summaries of the absolute fuel economy, fuel economy
improvement, incremental new vehicle cost, payback and lifetime savings for the reduced
roadload scenarios for large SUV and midsize car classes. These tables are in the same format as
those for the base roadload scenarios in the Executive Summary. Though there are a few
exceptions, in general the reduced roadload scenarios yield higher absolute fuel economy levels,
higher fuel economy improvements, higher incremental vehicle costs, lower payback periods,
and higher lifetime savings relative to the base roadload results in Tables ES-1 and ES-2.
2 Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards, National
Research Council, 2002.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page A-l
-------
APPENDIX A
Table A-l:
Key Projections for Large 4WD SUV Modeling Scenarios with Reduced Roadload
Reduced Roadload Case
Large Sport Utility Vehicle
(4WD) '
Fuel Economy (MPG) *
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Fuel Economy Improvement (%)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
New Vehicle Cost Increase ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Consumer Cost Payback (Years)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Vehicle Lifetime Savings ($) to Consumer
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
18.6
25.7
22.0
29.7
21.5 ! 22.3
30.1 ! 30.8
25.7 I 26.2
35.3 | 35.9
22.9 ! 27.2
31.4 j 38.2
26.5 I 28.7
36.4 | 41.2
8%
50%
28%
73%
25% j 30%
75% i 80%
50% ! 53%
106% I 109%
33% j 58%
83% ! 123%
54% ! 67%
112% I 140%
$210
$1,878
$742
$2,405
$1,531 j $1,546
$3,193 j $3,209
$2,032 | $2,048
$3,697 ! $3,714
$762 j $785
$2,427 j $2,451
$1,265 • $1,294
$2,931 ! $2,959
1.3
3.2
1.8
3.2
4.1 I 3.6
4.3 | 4.2
3.3 j 3.2
4.2 | 4.1
1.6 | 1.1
2.8 | 2.3
1.9 j 1.7
3.0 | 2.7
$888
$2,723
$2,267
$3,431
$1,945! $2,328
$3,434 ! $3,602
$3,222 I $3,367
$4,104 i $4,192
$3,372 ! $4,931
$4,544 ! $5,827
$4,261 I $4,885
$5,057 j $5,778
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page A-2
-------
APPENDIX A
Table A-2:
Key Projections for Midsize Car Modeling Scenarios with Reduced Roadload
Reduced Roadload Case
Midsize Car
(2WD)
Fuel Economy (MPG) *
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Fuel Economy Improvement (%)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
New Vehicle Cost Increase ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Consumer Cost Payback (Years)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Vehicle Lifetime Savings ($) to Consumer
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
-------
APPENDIX B
Appendix B: Discussion of Efficiency Benefits of and Design
Options for Increasing Average Engine Load Factor
In the design of a motor vehicle, an onboard source of motive power must be provided in order
to propel the vehicle in a manner responsive to the wishes of the driver. The demands of normal
driving call for a wide range of power demands and speeds. In a conventional automotive
powertrain design, an internal combustion engine (ICE) is employed as the source of motive
power. The ICE may act through a speed reducing gearbox of various sorts, but the power
demanded of the ICE is directly linked to road load demand. While the average power
demanded by normal driving is quite small, intermittent events such as rapid acceleration,
passing, and hill climbing demand power outputs far in excess of the average. Therefore, owing
to the situation of the ICE in this type of powertrain, the ICE must be sized to accommodate the
maximum anticipated intermittent power demand rather than the average power demand.
The sizing of the ICE to the maximum power demand results in a powertrain of relatively poor
efficiency. ICEs create mechanical work from fuel energy by combusting the fuel over a
thermodynamic cycle consisting typically of four cycles, namely intake, compression, expansion,
and exhaust. The best energy conversion efficiency of an ICE is experienced over only a
relatively narrow range of loads and speeds. Specifically, efficiency tends to be better at high
load than at low load, and better at moderate speed than at either low speed or high speed. An
automotive ICE that is sized to the maximum intermittent power demand will operate at low to
moderate power levels the vast majority of the time, where efficiency is relatively poor. This
results in a much lower fuel economy than could potentially be achieved.
One approach to improving fuel utilization would call for operating the ICE within its most
efficient operating range over a larger fraction of the typical driving cycle. The most obvious
approach would simply reduce the power rating of the ICE closer to the average power demand,
so that the peak efficiency range of the engine more frequently matches the power demanded by
the driver. However, the ability to meet peak power demands would then be compromised,
leading to unacceptable performance, driver confidence, and safety. Successfully utilizing the
efficient portion of the operating range would require a more sophisticated approach that would
also include a means to provide for intermittent bursts in power that are required by normal
driving.
Several broad strategies for achieving this outcome have been attempted with varying levels of
success.
Approach 1: Load-Leveling a Prime Mover
An auxiliary power unit (APU) might be added to provide intermittent assistance to the ICE.
This "load-leveling" strategy would allow average power demands to be met by a relatively low
power ICE having a peak efficiency near the average road load power demand, while the APU
supplements the ICE to meet larger power demands. Such an APU can take many forms. For
example, an electric motor and battery, or hydraulic pump/motor and accumulator, could be
employed as the APU. These particular technologies offer an added benefit because they offer
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page B-l
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APPENDIX B
the possibility of a two-way power flow between the ICE and the APU. This strategy allows
continued operation of the ICE at a high load, high efficiency state even when road power
demand falls below its efficient operating range. Energy taken from the wheels during braking
may also be reclaimed and reused with such a system. The main drawback of this load-leveling
approach is the added complexity of the powertrain. APUs that offer a two-way power flow
cannot be internal-combustion devices, meaning that the APU represents an additional subsystem
that would otherwise not be present, adding complexity and cost.
Approach 2: Primary and Secondary Engines
Another approach could discard the idea of a two-way APU and instead adopt a second ICE as
the APU. This would create a multiple-engine powertrain. In such a system, the additional
engine(s) might normally be inactive but be intermittently engaged to provide power bursts at
times when a primary engine, sized to an average power demand, is not adequate to meet such
demands. Alternately, each engine could be sized to serve a specific range of demands at which
their respective efficiency is greatest. A general shortcoming of such a powertrain is the need to
frequently start and stop the various engines. Prevailing ICE technologies, if used in such a
system, would encounter some efficiency losses and increased emissions as a result of frequent
restarting. Driver confidence might also be negatively influenced if the driver perceives the
frequent starting and stopping of the engines as a reliability risk.
Approach 3: Variable Displacement
The multiple-engine powertrain discussed previously may be described more broadly as one
form of a variable-displacement powertrain. That is, a sort of variable displacement is achieved
by switching the various engines on or off. Variable displacement has more commonly been
achieved by changing the displacement of a single engine, perhaps by variably switching one or
more of its cylinders on or off. Many approaches have been used to control the participation of
the various cylinders, including the selective feeding of fuel to each cylinder, variable control of
exhaust and intake valves, and physical disconnection of cylinders or their parts. All of these
methods have drawbacks. If the piston of a non-participating cylinder continues to reciprocate
within its cylinder, friction losses will be significant. Even if compression forces are minimized
by selectively opening the valves, there is still a price to be paid in terms of friction, pumping
losses, and inertial effects for each cylinder that is not producing power at a given time.
Approach 4: Low Speed Operation
Friction is a significant cause of inefficiency in a piston-based ICE. Because friction loss per
unit power delivered is greatest at higher engine speeds, operating the engine at a relatively low
average speed may improve efficiency by reducing the influence of friction. If such a low-speed
engine were properly designed, peak power demands could be met by intermittent operation at
higher speeds. Low-speed engines have not been a popular approach in the prior art in part
because current engine and drivetrain designs do not respond well to low speed operation. At
low engine speeds, torque pulses on the crankshaft are more distinctly felt on the output shaft.
Conventional gearboxes would tend to transmit these pulses to the vehicle, resulting in less
comfort and reduced component durability. Optimum fuel injection timing is also very critical at
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page B-2
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APPENDIX B
low speed operation, requiring more sophisticated control. Also, the relatively slow piston stroke
would allow more time for heat to be lost to the surroundings during the expansion stroke, and
more opportunity for leakage of gases past the rings during the compression stroke. Combustion
processes might also be negatively affected by stroke speed and cycle length, reducing mixing
efficiency and combustion quality. Finally, because the kinetic energy of the crankshaft varies
with velocity squared, reducing the speed beyond a certain point will dramatically increase the
risk of stalling on the compression stroke. A heavier flywheel could alleviate this problem, but it
would make the drivetrain less responsive, especially at higher speeds.
Approach 5: Switching Between Four-Stroke and Two-Stroke Operation
Another method would selectively switch between four-stroke and two-stroke operation. The
four-stroke cycle has been preferred in automotive applications because it provides better
efficiency and emissions than a two-stroke cycle. However, a two-stroke cycle, having twice as
many power strokes per cycle, could theoretically double the power output of an engine of given
size. Thus the ability to switch between four-stroke and two-stroke operation would allow a
small four-stroke engine to meet average power demands at optimum efficiency and minimum
emissions, while a two-stroke mode could be engaged to meet peak power demands
intermittently. A primary drawback of this approach is the difficulty of achieving acceptable
emissions and efficiency in two-stroke mode. Conventional two-stroke operation relies on an
imperfect "scavenging" process that takes the place of separate intake and exhaust strokes and
results in the escape of unburned fuel with the exhaust, resulting in high hydrocarbon emissions
and loss of fuel efficiency. A dramatic boost in power is achieved as the scavenging process
approaches 100% efficiency (owing to the purity of the fresh air in the mixture), but nearly
perfect scavenging is elusive. There are several approaches to "scavenging" including cross-
scavenging, loop-scavenging, and uniflow methods, but none are perfect. Generally, scavenging
may be improved with variations in porting and piston shaping, the clutching in of a
supercharger, or a 4-valve design. The combustion chamber of such an engine would also be
designed to have peak efficiency in four-stroke operation while providing maximum scavenging
in two-stroke operation. The two-stroke mode would call for direct cylinder fuel injection and
full flexibility of fuel injection timing. Switching between modes would require total control of
intake and exhaust valve mechanisms, not the mechanical valve control typically employed.
Approach 6: Variable Compression Ratio
Perhaps the most practical way to improve engine efficiency is to increase the compression ratio
(CR) of the engine. The compression ratio is simply the ratio of expanded cylinder volume to
compressed cylinder volume in one cycle of the reciprocating piston. According to
thermodynamic laws, a greater degree of compression relative to the expanded volume
corresponds to greater efficiency of the thermodynamic cycle and hence greater efficiency of the
engine. Unfortunately, a large compression ratio promotes several undesirable side effects. An
increased level of friction and higher peak cylinder pressures are two results of a high
compression ratio. Under these conditions, if the fuel is introduced with the fresh charge air,
there is a potential for knocking or pre-ignition at high power output. For this reason, if the
compression ratio of a normal engine were simply increased without other allowances being
made, the efficiency at low power output might improve, but operation at higher power outputs
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page B-3
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APPENDIX B
would be compromised by severe knocking. This would not only reduce efficiency significantly
but could potentially lead to engine damage.
These problems could be avoided if a high-compression engine could selectively reduce its
compression ratio at times when high power output is needed. Ideally, one would desire to
employ a high compression ratio at normal load, and shift to a lower compression ratio for
intermittent high loads. In this way the high efficiency associated with a high compression ratio
could be achieved over normal ranges of operation, while higher power output could be achieved
without fear of pre-ignition by invoking a lower compression ratio.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page B-4
-------
APPENDIX C
Appendix C: Description of EPA's Variable Displacement
Engine Design
EPA's variable displacement engine design varies displacement by use of a multiple-crankshaft
engine design in which two distinct crankshafts are contained within a single engine block. The
crankshafts are independent so that each can rotate singly or in combination. For example, a first
crankshaft operates pistons which represent, for example, two liters of displacement, and a
second crankshaft operates pistons which represent an additional two liters of displacement or a
different displacement. When relatively low power is needed, the first crankshaft unit is
operated alone at a higher relative load than if all crankshaft units were operating, thus allowing
it to operate at a higher relative efficiency. When higher power is commanded than can be
supplied by the first crankshaft unit, the second crankshaft unit is activated, and together the two
crankshaft units supply the commanded power.
EPA's variable displacement engine design provides several advantages necessary for
commercial practicality and acceptance: 1) uninterrupted accessory drive; 2) low cost of
manufacture, including operability with conventional automotive components, and minimal
duplication of components (starting, cooling, lubrication, accessories, and other support
systems); 3) smooth transitioning among units of displacement; 4) good lifetime and reliability;
and 5) an option for multiple output shafts for use with unconventional hybrid drive systems.
Uninterrupted Accessory Drive
The EPA variable displacement engine design utilizes a unique means to allow a zero
displacement mode without interrupting power to accessories that require a direct power drive.
One option provides a separate power drive accessories system which operates the accessories
with a drive motor (e.g., electric or hydraulic) independent of either crankshaft unit. This option
allows the accessories to be driven at a speed that is optimum for the demands being placed on
the accessories. In a second configuration, this drive system is mounted to the engine with drive
attachments (through clutch means) to each crankshaft, and in this configuration the separate
drive motor drives through clutch means as well. When either crankshaft unit is operating, the
accessories are directly driven by power from the operating crankshaft(s). When neither
crankshaft unit is operating, the drive motor drives accessories through its clutch drive means. A
third option for satisfying accessory needs is to insure at least one crankshaft unit will be
operating when accessory needs exist, and the separate drive motor of the previous configuration
can be deleted.
Low Cost of Manufacture
Low cost of manufacture includes maintaining operability with conventional automotive
components and minimal duplication of components.
The EPA variable displacement engine design utilizes a single starter to start both displacement
units. One option includes a single starter which can engage a first crankshaft unit to start it and
then when more power is commanded than the first crankshaft unit can supply alone, the starter
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page C-l
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APPENDIX C
engages a second crankshaft unit to start it. In a second option the first crankshaft unit is started
with a dedicated starter and the second unit is started by activating its clutch to rapidly raise its
speed to that of the first crankshaft unit.
By integrating the separate crankshafts into a common block, each displacement unit shares the
same cooling system and lubrication system.
Compatibility of the power plant with existing automotive components would be assured by (a)
providing means as described above to drive conventional power drive accessories without
interruption, allowing off-the-shelf components to be used without substantial redesign; and (b)
delivering a single output shaft for attachment to conventional transmissions by means of a
unique clutching and gearing system.
It would also be possible to designate one displacement unit as a secondary unit that receives
intermittent use, which allows it to be constructed less expensively than the primary unit.
Smooth Transitioning
Smooth transitioning among various units of displacement can be achieved by adopting an
operating strategy in which one displacement unit is designated as a permanent secondary unit
and its flywheel is eliminated, allowing it to spin up faster.
Reliability and Lifetime
Reliability and lifetime would be improved when the two displacement units may
interchangeably serve as primary or secondary displacement units, which acts to reduce the
potential for uneven wear, and guarantees that a first increment of displacement is always
available for emergency use even when one of the units has failed.
Option for Multiple Output Shafts
It is also possible to provide separate crankshaft outputs to provide certain advantages for
powertrains which transmit power to the drive wheels by electric or hydraulic motors.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page C-2
-------
APPENDIX D
Appendix D: Description of EPA's Variable Compression
Ratio Engine Design
The EPA variable compression ratio engine design achieves a two-stage variation in compression
ratio by use of a piston-within-piston mechanism that varies the combustion and mixing volume
provided within the piston crown, thereby regulating the net clearance volume at top dead center
(TDC) without changing the main piston squish height.
In normal operation (during low to moderate power demands), the top of an inner piston is flush
with the top of an outer piston, defining a normal high compression ratio mode. The relatively
high compression ratio in this mode provides excellent thermodynamic efficiency in this normal
operating range. When power demand increases to the point where this high compression ratio
might cause performance problems such as pre-ignition or knocking, a command signal causes
the inner piston to recede to a second position within the outer piston, thereby increasing the total
clearance volume and reducing the compression ratio sufficiently to prevent pre-ignition or
knocking. Good mixing and combustion is retained in both modes because the piston bowl
resides within the receding inner piston and therefore does not change shape, only changing its
relative distance from the top of the cylinder head at TDC.
The inner piston is located in either the normal high CR position or the intermittent low CR
position by the rotation of a rotary cam-like actuator which pivots about a wrist pin residing in
the outer piston. The rotary actuator is comprised of a rotary hydraulic piston and fluid chamber
that are integrated with the wrist pin, and a cam which pivots around the wrist pin in reaction to
movement of the hydraulic rotary piston. Movement of the hydraulic rotary piston and cam
assembly is caused by the presence or absence of a hydraulic command signal consisting of a
pulse of pressurized hydraulic fluid, in conjunction with inertial forces created by reciprocation
of the piston assembly in an engine cylinder. The issuance of the command signal activates the
intermittent low-CR mode. Withdrawal of the command signal allows a spring mechanism and
inertial forces to restore a normal high-CR mode.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page D-l
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APPENDIX E
Appendix E: Engine Maps
This appendix provides the four engine maps that were used in the fuel economy modeling of the
various vehicle technology packages that were discussed in Section 5. These maps show fuel
energy efficiency (shown in the "islands" in the middle of the charts) as a function of engine load
(torque, the vertical axis) and engine speed (revolutions per minute, or rpm, on the horizontal
axis).
Figure E-l: SUV Baseline GAS Engine
SUV Baseline Gas Engine
SUSP
Figure E-2: SUV Baseline Diesel Engine
SUVBaselmeL'iese Engine
Figure E-3: Car Baseline Gasoline Engine
CAR Baseline Gas Engine
Figure E-4: Car Baseline Diesel Engine
CAR Baseline Diesel Engine
500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000
RPM
2000 2500
RPM
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page E-l
-------
APPENDIX F
Appendix F: Hydraulic Pump/Motor Maps
This appendix provides the five hydraulic pump/motor maps that were used in the fuel economy
modeling of the various hydraulic hybrid vehicle technology packages that was discussed in
Section 5. These maps show pump/motor efficiency (shown in the "islands" and lines in the
middle of the charts) as a function of displacement (the vertical axis) and pump/motor speed
(revolutions per minute, or rpm, on the horizontal axis). The maps represent a high-efficiency
unit tested at five different pressures.
Figure F-l: 2000 PSI
...
Figure F-2: 2500 PSI
Figure F-3: 3000 PSI
Ifflo joe
Figure F-4: 3500 PSI
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
pageF-l
-------
APPENDIX F
Figure F-5: 4000 PSI
Gen 2 4000 PSI
1000 1500 2000 2500 3000 3500
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page F-2
-------
APPENDIX G
Appendix G: Derivation of Base Roadload Specifications
Appendix G provides the background material on the base roadload specifications that are one of
the major inputs to the fuel economy modeling described in Section 5. The base roadload is
calculated as the sales-weighted average roadload specifications for today's top-selling vehicles
in the large SUV and midsize car classes. The automobile manufacturers supplied roadload
equations to EPA as part of their submission for emissions certification of 2002 model year
vehicles. Table G-l provides the roadload specifications for top selling 2002 models in the large
SUV and midsize car classes. These were weighted together to form the base roadload
specifications for the body of this report. For the reduced roadload case supplied in Appendix A,
the base roadload specifications were lowered by 20 %.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page G-l
-------
APPENDIX G
Table G-1
Emissions/Fuel Economy Test Cars - Track Roadload Coefficients, Curb Weight, ETW
2002 Models - Representative Models
Top Selling Model Lines within Selected Classes
LARGE SUV
MAKE
Chevy
Chevy
CMC
CMC
Ford
Toyota
TRACK COEFF
ABC
MODEL LINE ENG/ETW MODEL Ibs Ibs/mph Ibs/mph2
Tahoe 5.3 L/6000 4WD 58.57 1.1649 0.03022
Suburban 5.3 L/6500 4WD 61.33 1.1653 0.03202
Yukon 4.8 L/6000 4WD 41 .65 1 .2249 0.02792
Yukon Denali XL 6.0 L/6000 AWD 56.02 1.2954 0.02872
Expedition 5.4 L/6500 4WD 52.63 1 .5779 0.03069
Sequoia 4.7 L/6000 4WD 53.33 0.59261 0.03497
Sales Weighted Average 56.69 1.1514 0.03121
MID-SIZE CARS
Ford
Toyota
Honda
Buick
Taurus 3.0 L/3625 SE 29.72 0.2625 0.0182
Camry 2.4 L/3500 XLE 28.621 0.09621 0.01964
Accord 2.4L/3375 LX Sedan 26.01 0.4918 0.01591
Century 3.4L/3625 Custom 25.43 0.5118 0.01634
Sales Weighted Average 27.52 0.31624 0.01771
CURB
WT
Ibs
5049
5142
5103
5820
5449
5295
5263
3336
3219
3097
3368
3240
ETW CITY HWY
Ibs mpq mpq
6000 14.9 21.9
6500 14.7 21.5
6000 15.4 21.5
6000 12.8 19.1
6500 13.4 21
6000 15.4 22
3625 22.2 35.4
3500 25.3 39.2
3375 25.8 38.8
3625 22.3 36.7
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page G-2
-------
APPENDIX H
Appendix H: Detailed City/Highway Fuel Economy Results
The body of the report uses composite fuel economy values where the city and highway values
are harmonically averaged and weighted 55% city/45% highway. The table in this appendix
provides the individual city and highway fuel economy modeling results for each of the vehicle
technology packages.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page H-l
-------
APPENDIX H
SUV Target from EPA Database
SUV— Base Roadload
Conv Gasoline Engine
Gasoline Var Disp Engine
Clean Diesel Engine
Diesel Var Disp Engine
SUV-Reduced Roadload
Conv Gasoline Engine
Gasoline Var Disp Engine
Clean Diesel Engine
Diesel Var Disp Engine
SUV— Base Roadload
Conv Gasoline Engine
Gasoline Var Disp Engine
Clean Diesel Engine
Diesel Var Disp Engine
SUV-Reduced Roadload
Conv Gasoline Engine
Gasoline Var Disp Engine
Clean Diesel Engine
Diesel Var Disp Engine
Car Target from EPA Database
Car— Bas
Conv Gasoline Engine
Gasoline Var Disp Engine
Clean Diesel Engine
Diesel Var Disp Engine
Car-Reduced Roadload
Conv Gasoline Engine
Gasoline Var Disp Engine
Clean Diesel Engine
Diesel Var Disp Engine
Car— Base Roadload
Conv Gasoline Engine
Gasoline Var Disp Engine
Clean Diesel Engine
Diesel Var Disp Engine
Car-Reduced Roadload
Conv Gasoline Engine
Gasoline Var Disp Engine
Clean Diesel Engine
Diesel Var Disp Engine
15.0 21.0 17.2
Conventional Transmission
city mpg
14.9
18.0
20.9
24.2
city mpg
15.7
19.4
22.2
26.1
24.0
Conventic
city mpg
24.3
30.5
33.1
39.7
city mpg
25.2
32.1
34.7
42.0
hwy mpg
21.2
22.2
27.8
30.7
hwy mpg
24.1
26.3
31.9
36.0
38.0
nal Trans
hwy mpg
38.0
43.8
52.7
60.5
hwy mpg
41.8
49.8
59.2
68.7
comb mpg
17.2
19.7
23.6
26.8
comb mpg
18.6
22.0
25.7
29.7
28.8
•Mission
comb mpg
29.0
35.3
39.8
46.9
comb mpg
30.7
38.2
42.6
50.9
% Gain(loss)
15
37
56
% Gain(loss)
8
18
38
60
8
28
50
73
% Gain(loss)
22
37
62
% Gain(loss)
6
25
39
66
6
32
47
76
Mild Hy
city mpg
18.7
23.6
27.2
32.0
city mpg
20.3
26.3
29.6
36.0
hwy mpg
20.4
21.3
26.9
29.6
hwy mpg
23.2
25.1
30.7
34.6
comb mpg % Gain(loss)
19.4 13
22.5 31
27.0 57
30.9 80
comb mpg
21.5
25.7
30.1
35.3
% Gain(loss)
Mild Hyi
city mpg
19.7
24.2
28.2
32.7
city mpg
16 25 21.6
38 50 27.2
62 75 30.8
90 106 36.8
Full Hy
city mpg
19.9
23.8
27.7
33.3
city mpg
22.0
26.9
31.1
37.7
hwy mpg
20.5
21.7
26.6
29.0
hwy mpg
24.0
26.0
31.9
34.9
comb mpg % Gain(loss)
20.2 18
22.8 33
27.2 59
31.2 82
comb mpg
22.9
26.5
31.4
36.4
% Gain(loss)
hwy mpg
20.5
21.3
26.9
29.7
hwy mpg
23.3
25.1
30.8
34.9
comb mpg
20.0
22.8
27.6
31.3
comb mpg
22.3
26.2
30.8
35.9
% Gain(lo
17
33
61
82
ss)
|
% Gain(loss)
20
41
66
93
Full Hyc
city mpg
25.6
26.8
35.9
38.7
city mpg
23 33 29.9
42 54 31.2
69 83 41.8
96 112 45.4
Mild Hy
city mpg
29.6
39.9
46.5
57.0
city mpg
31.2
43.0
49.6
62.6
hwy mpg
36.7
41.8
51.2
58.2
hwy mpg
40.6
47.8
57.3
66.8
comb mpg % Gain(loss)
32.4 12
40.7 41
48.5 67
57.5 99
comb mpg
34.8
45.1
52.8
64.4
% Gain(loss)
hwy mpg
20.6
21.5
28.2
30.6
hwy mpg
24.5
26.1
34.6
37.1
comb mpg
23.1
24.1
32.0
34.6
comb mpg
27.2
28.7
38.2
41.2
% Gain(lo
34
40
86
101
30
53
80
109
ss)
|
% Gain(loss)
46
54
105
122
Mild Hyi
city mpg
32.1
42.1
49.3
60.1
city mpg
13 20 34.0
47 56 45.8
72 82 53.8
110 122 66.8
Full Hy
city mpg
33.4
44.2
48.0
58.6
city mpg
36.0
49.1
52.2
64.6
hwy mpg
39.7
44.1
52.6
58.7
hwy mpg
45.4
52.0
60.1
69.1
comb mpg % Gain(loss)
36.0 24
44.1 52
50.0 72
58.7 103
comb mpg
39.7
50.4
55.5
66.6
% Gain(loss)
hwy mpg
36.8
41.8
51.3
58.4
hwy mpg
41.1
47.9
57.6
66.9
comb mpg
34.0
42.0
50.2
59.3
comb mpg
36.8
46.7
55.5
66.9
% Gain(lo
18
45
73
105
58
67
123
140
ss)
|
% Gain(loss)
20
52
81
118
Full Hyc
city mpg
45.3
47.2
62.4
67.2
city mpg
29 37 51.4
64 74 52.8
81 92 70.3
117 130 75.4
hwy mpg
41.5
43.5
57.0
61.1
hwy mpg
48.9
51.7
67.2
72.8
comb mpg
43.5
45.4
59.9
64.3
comb mpg
50.2
52.3
68.9
74.2
% Gain(lo
50
57
107
122
27
61
92
131
ss)
|
% Gain(loss)
64
70
124
142
73
81
138
156
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page H-2
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APPENDIX I
Appendix I: FEV Report - Cost and Fuel Economy
Comparison of Diesel and Gasoline Powertrains in
Passenger Cars and Light Trucks
This appendix contains a report written by FEV to estimate the cost for a clean diesel engine.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page 1-1
-------
Engine Technology
FEV01-505P3 Rev. 1 Final Report
Engine and Vehicle Development
and Engineering Support
Contract No. 68-C-01-155
Work Assignment 0-2 Amendment 2
Cost and Fuel Economy Comparison
of Diesel and Gasoline Powertrains in
Passenger Cars and Light Trucks
Prepared for:
Jeff Alson and Tom Bejma
US Environmental Protection Agency
Office of Transportation and Air Quality
National Vehicle and Fuel Emissions Laboratory
2565 Plymouth Road
Ann Arbor, Ml 48105
Submitted by :
FEV Engine Technology, Inc
4554 Glenmeade Lane
Auburn Hills, Ml 48326
April 23, 2003
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EPA Contract 68-C-01-155 WA 0-2 FEV01-505P3 Rev. 1 Final Report
April 23, 2003
Page ii
A. Executive Summary
Fuel economy and production cost differences for gasoline and diesel powered vehicles are
compared. Similar production volumes for gasoline and diesel engines and vehicles are
assumed, with the result that the economies-of-scale for the diesel engine and the gasoline
engine are equal. Furthermore, it is also assumed that the base vehicles' architecture will
have been initially designed to accept either engine. No effort was made to assess the
relative difference in exhaust aftertreatment systems. A "low-risk" approach to technology
was taken whereby engine and vehicle technology widely available in the 2002 world
automotive market is assumed.
A detailed vehicle simulation model was used to assess the relative fuel economy
difference between gasoline and diesel powered passenger cars and SUV's. The passenger
car comparison is based on vehicles in the mid-sized 5-passenger car class typified by the
Ford Taurus and Toyota Camry. Full-size SUV's typified by the Chevrolet Tahoe and Ford
Expedition are also compared. Vehicle performance with gasoline engines was predicted in
both vehicle classes and compared with published results for these vehicles. These values
were then used as a baseline for further comparisons. The diesel engine displacement and
output were adjusted to achieve parity in 0-60 mph acceleration between gasoline and diesel
engine powered vehicles. Fuel economy on the U.S. Federal fuel economy cycles (city and
highway) and vehicle performance using several metrics were predicted and compared.
Fuel economy figures that result from EPA test procedures are reported in miles per
gallon. The primary engine fuel consumption maps, which strongly influence the fuel
economy results, were developed independently and were not produced from vehicle
manufacturer-supplied data.
Estimated production cost and weight differences between gasoline and diesel engine
powered versions of the comparison vehicles were detailed. The primary factor leading to
the increased cost and weight of the diesel powertrain is the diesel engine, which is strongly
influenced by the cost of the high pressure diesel fuel injection system.
Table ESI summarizes the fuel economy, production cost, and weight differences for the
two (2) comparison vehicles with gasoline and diesel engines.
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City Fuel Economy
City FE Improvement
Highway Fuel Economy
Highway FE Improvement
Combined Fuel Economy
Combined FE Improvement
Vehicle Test Weight
Mature Production Cost Estimate
(2002 $)
Current Production Cost Estimate
(2002 $)
Passenger Car
Gasoline
24.8 mpg
Baseline
41.0 mpg
Baseline
30.2 mpg
Baseline
3550 Ibs
Baseline
Baseline
Diesel
36.7 mpg
48%
51.3 mpg
25%
42.1 mpg
39.5%
3643 Ibs
+ $739
+ $1063
Full-Size SUV
Gasoline
14.7 mpg
Baseline
21.0 mpg
Baseline
17.0 mpg
Baseline
5563 Ibs
Baseline
Baseline
Diesel
21.4 mpg
45%
28.1 mpg
33%
24.0 mpg
41%
5752 Ibs
+ $1042
+ $1537
Table ESI: Overall Results of the Study
For both passenger car and SUV diesel engines, high pressure common rail fuel injection
systems were assumed. The estimated cost for the common rail diesel fuel injection
system alone contributes $735 to the total difference of $1063 between the gasoline and
diesel engine powered passenger car using current cost estimates. Because common rail
diesel fuel injection technology is relatively new, initial development and capitalization
costs may significantly impact the estimated current production cost. FEV estimates that
the mature production cost of the complete fuel injection system could be reduced by
approximately 30% from the current cost estimate under the boundary conditions of the
study. For similar arguments, FEV estimates that the mature production cost of a variable
geometry turbocharger can also be reduced 30% from current estimate. These estimates
reduce the cost differential between gasoline and diesel engine powered vehicles.
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Table of Contents
A. Executive Summary ii
B. Introduction 1
C. Vehicle Performance and Fuel Economy Simulation 2
D. Cost and Weight Predictions 11
D.1 Gasoline and Diesel Engine 11
D.2 Vehicle Fuel System 15
D.3 Air Induction System 16
D.4 Powertrain Control System and Vehicle Electrical System 16
D.5 Powertrain Mounting System 17
D.6 Transmission and Drivetrain System 18
D.7 Other Contributors 18
D.8 Cost and weight prediction summary 19
E. Results 22
F. Appendix A-References 24
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Cost and Fuel Economy Comparison of Diesel and Gasoline
Powertrains in Passenger Cars and Light Trucks
B. Introduction
For the US market, diesel engines are proposed as a means to improve the fuel economy of
new passenger cars and light trucks.
In contrast to the US where diesel engine powered vehicles make up just 0.1% of new light
vehicle sales1'2' vehicles with diesel engines make up an increasingly large portion of the
new passenger car and light commercial vehicle fleet in the European market. The fuel
consumption advantage, price disparity between gasoline and diesel fuel in many countries,
along with rapidly advancing technology of high speed direct injection diesel engines by
European automakers, has increased the market penetration of diesel engines. European
Union emission standards also grant diesel powered cars and light commercial vehicles
different emissions requirements. The percentage of diesel engine powered light vehicles
in the European market has increased steadily over the last 30 years and rapidly in the last 5
years, as shown in Table 1.
Year
1973
1994
2000
2001
Diesel %
2.5
22.7
34.9
35.8
Table 1. Percentage of new car registrations in Europe with diesel engines 3
This study compares estimated production cost (without economic inflation) and simulated
fuel economy of two classes of vehicles with gasoline and diesel engines for the US light
vehicle market. Vehicle models that are typical to the US automotive market are studied. It
is projected that by the year 2010, vehicles could be developed for use with gasoline or
diesel engines in similar production quantities. It is assumed that vehicle designs would be
completed with both engine options fully engineered, rather than initially developed with
the gasoline engine and then modified for a diesel engine after the platform is already
designed.
In this study, the technology level associated with each powertrain is already in mass
production in the 2002 world automotive market. For example, the baseline passenger car
gasoline engine assumes a primarily aluminum construction spark-ignited, homogeneous
charge engine with variable intake valve timing. A conventional 4-speed automatic
transmission is also applied to every vehicle in the study. The diesel engine technology is
typical of 2002 model European diesel engines, including common rail fuel injection,
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Page 2
variable geometry turbocharging, and electronic EGR control. Evolution in the
development of both gasoline and diesel engines that could improve engine performance
and fuel economy is not considered.
Two vehicle comparisons are considered. The first is a 5-passenger sedan typified by the
2002 model year Ford Taurus, Chrysler Sebring, Saturn LS, Honda Accord, and Toyota
Camry. This class of vehicles makes up the largest segment of the passenger car market in
the US. A full size SUV typified by the 2002 model year Chevy Tahoe, Ford Expedition,
and Toyota Sequoia is the second comparison vehicle. Large SUV's represent a vehicle
class with low fuel economy ratings and growing market penetration, so the difference in
fuel use in gallons per year for this class of vehicle would be anticipated to be relatively
large and potentially growing.
This study does not consider the exhaust aftertreatment system necessary to allow either
gasoline or diesel vehicles to meet US emissions standards in the 2010 time frame. The
cost and fuel economy implications must be applied in addition to the final findings of this
study. Such an approach should be taken cautiously, because the engine cost may be
impacted by the need to meet very low emissions requirements. Further, it is FEV's
experience that the exhaust aftertreatment system technology necessary to meet a
challenging emissions level must be developed in conjunction with the base engine in a
complete systems approach.
This study does not consider the impact of other technologies on the relative fuel
consumption and cost of either gasoline or diesel engine system. It is expected that 42V
electrical systems, advanced transmissions, and hybrid powertrains can be analyzed relative
to gasoline and diesel engines on a cost/benefit basis.
C. Vehicle Performance and Fuel Economy Simulation
Detailed simulation models of gasoline and diesel powered vehicles were prepared and
evaluated. Parameters chosen for simulation, including engine maps, were determined
independently and were not developed utilizing vehicle manufacturer-supplied data. Actual
engine and vehicle calibrations could differ significantly from those assumed under this
study.
Vehicle performance simulation was performed using a computer simulation program
developed internally by FEV. FEV's vehicle simulation model has capabilities similar to
those of commercial vehicle performance simulation models such as GT-Drive from
Gamma Technologies or the proprietary software used by automakers. FEV has correlated
simulation model predictions to measured vehicle performance to validate the model
capabilities.
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Using this model, vehicle performance can be predicted for a time sequenced vehicle speed
profile (e.g. FTP75) to predict performance on prescribed cycles. It is also possible to
assess vehicle acceleration performance times between prescribed speeds (e.g. 0-60 mph,
30-50 mph).
Vehicle properties are entered including engine torque curve and primary engine fuel rate
map as a function of engine speed and load. Engine fuel rate maps are based on engine test
data measured on competitive engines from the world automotive market. All data used in
this study is based on engines in mass production during the 2002 model year.
Equivalent vehicle acceleration performance for each comparison set of vehicles was
required. Zero to 60 mile per hour acceleration time was chosen as the key performance
metric. The diesel engine output curve and final drive ratio were selected to achieve parity
in 0-60 mph acceleration performance for gasoline and diesel versions in each comparison
vehicle class. The engine torque curves were determined using base engine performance
measured on existing production engines from the world automotive market. To achieve
performance parity of the comparison vehicles, the engine displacement was scaled to
increase or decrease total engine output. Fundamental transmission characteristics such as
gear efficiencies and vehicle properties were unchanged from gasoline to diesel vehicles.
The primary differences in the gasoline and diesel vehicle simulation models are the peak
engine output curve and the engine fuel consumption map, which contains tabulated fuel
consumption rates as a function of engine speed and output torque. The final drive ratio was
adjusted for the diesel engine to optimize the vehicle fuel economy while achieving
equivalent acceleration performance. For all vehicles, the automatic transmission shift map
was estimated. The fuel consumption map used in this study for the passenger car with a
gasoline engine is shown in Figure 1.
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EPA Contract 68-C-01-155 WA 0-2
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Passenger Car Gasoline Engine
Fuel Consumption Map [g/bkW-hr]
250
200-
150-
0)
CT
100-
50-
1000
2000
3000
4000
5000
6000
[rpm]
FEW
Figure 1. Passenger car gasoline engine fuel consumption map
The diesel engine fuel consumption maps are typical of diesel engines available on the
European market in 2002. The diesel engine fuel consumption map used in this study for
the passenger car is shown is Figure 2.
For both gasoline and diesel engines, no improvement in engine fuel consumption over
today's engines is assumed or implemented in the vehicle simulation models.
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April 23, 2003
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Passenger Car Diesel Engine
Fuel Consumption Map [g/bkW-hr]
350
300-
250-
200-
150-
100-
500
1000
2000
2500
3000
3500
4000
4500
[rpm]
FEW
Figure 2. Passenger car diesel engine fuel consumption map
Using the developed simulation models, fuel economy and other performance metrics were
then evaluated. Fuel economy figures quoted in this study represent the miles per gallon
figure that can be achieved on EPA laboratory tests. Fuel economy figures are reported in
miles traveled per gallon of respective fuel consumed.
The different economy results are not adjusted for fuel density. A gallon of diesel fuel
typically weighs about 10% more than a gallon of gasoline. The fuel density assumed for
this study is shown in Table 2.
Fuel
Gasoline
Diesel
Specific
Gravity
0.764
0.85
Table 2. Gasoline and diesel fuel specific gravity assumed for this study
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City and highway fuel economy figures were obtained using the vehicle simulation models
on the prescribed vehicle speed cycles. Combined fuel economy was calculated using the
following relationship:
Combined FE =
(0.55 / City FE) + (0.45 / Highway FE)
Acceleration performance from 0-60 miles per hour was assessed using a specific vehicle
test procedure. The vehicle is idled with the automatic transmission selector in drive. At
time zero, the accelerator pedal is depressed from 0 to 100% in less than 100 msec. The
time when the vehicle passes 60 mph is measured to determine total accumulated
acceleration time. The simulation procedure matches FEV's vehicle test procedure to
measure acceleration time. Automotive enthusiast magazines report shorter acceleration
times, but the test procedure is not equivalent.
Baseline results for the gasoline powered vehicles were compared to data which FEV
obtained from EPA testing for city and highway fuel consumption values and zero to sixty
mph times FEV had measured in actual vehicle road tests. These values were used to "tune"
model parameters and act as validation for the parameter sets.
The engine torque output map for gasoline engines was taken from measured engine
performance tests. The necessary output from the diesel engine was estimated to achieve
equivalent vehicle acceleration from 0-60 mph. The engine torque curve and fuel economy
map was then scaled from actual measured engine data. Figures 3 and 4 illustrate the
maximum engine performance from the passenger car gasoline and diesel engines included
in this study.
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EPA Contract 68-C-01-155 WA 0-2
175
150
125
"S 100
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0)
o
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75
50
25
FEV01-505P3 Rev. 1 Final Report
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Passenger Car Engine Power
— • — Gasoline Engine |
uiet>
X
p
•
0
/
/
I •
1
3\ Engin
. .0
• '
X
i
e
,;>'
I'' X
(
'^
:
•
•
•
X*\
\
<
i
0 1000 2000 3000 4000 5000 6000 7000
Engine Speed [rpm]
Figure 3. Gasoline and diesel engine maximum power output
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EPA Contract 68-C-01-155 WA 0-2
FEV01-505P3 Rev. 1 Final Report
April 23, 2003
Page 8
Passenger Car Engine Torque
350
0)
A
U
A
U
A
A
A
n
n -
c
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) 10
n
P
j
00 20
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' 'B.
ft
^-* '
00 30
— • — Gasoline Engine )
•- - - n
u
'l
r- '
00 40
n
•
*'
00 50
esel Engine (^
^\
>
00 60
00 70
Engine Speed [rpm]
Figure 4. Gasoline and diesel engine maximum torque output
The simulation portion of the study quantified the displacement, output, and configuration
of diesel engine needed to achieve equivalent vehicle acceleration. This information was
needed to provide a boundary for the cost portion of the study.
For SUV and passenger cars with gasoline engines, the vehicle test weight used in the
simulation model was based on average manufacturer data for equivalent 2002 model year
vehicles. The vehicle test weight is equivalent to the vehicle curb weight plus 300 pounds
for driver and instrumentation. Although it is possible that vehicle weight will decrease by
the year 2010 through the continued increase in use of lighter materials and advanced
structural optimization methods, some increase in weight is also possible because of the
increased use of safety equipment in cars. It was therefore decided to maintain vehicle
weight at values typical for the vehicle class in the 2002 model year.
The diesel powertrain is expected to add weight to the vehicle. To evaluate the comparison
vehicles fairly, FEV also estimated the weight penalty that a diesel powertrain would add to
the comparison vehicles. The weight of fuel included in the test weight of each vehicle was
adjusted for gasoline or diesel. The fuel tank capacity of gasoline and diesel comparison
vehicles was changed to produce equivalent vehicle range (using combined city/highway
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Page 9
fuel economy). The vehicle test weight includes an assumption that the tank is half full, and
the difference in fuel density is taken into account. Table 3 summarizes the difference in
vehicle weight attributed to the fuel.
Combined fuel economy
Range (miles)
Fuel tank capacity (gallons)
Half tank capacity (gallons)
Weight of 1 gallon of fuel
Total fuel contribution to
Vehicle Test Weight (Ibs)
Weight reduction for diesel
Passenger Car
Gasoline
30.2 mpg
513 miles
17 gal
8. 5 gal
6.4 Ibs
54.5 Ibs
Baseline
Diesel
42.1 mpg
513 miles
12.2 gal
6.1 gal
7.1 Ibs
43.3 Ibs
(11. 2 Ibs)
Full-Size SUV
Gasoline
17.0 mpg
442 miles
26 gal
13 gal
6.4 Ibs
83.2 Ibs
Baseline
Diesel
24.0 mpg
442 miles
18.4 gal
9. 2 gal
7.1 Ibs
65.4 Ibs
(17.8 Ibs)
Table 3: Difference in fuel weight for equivalent range
The modeled drag coefficient for passenger cars and SUV's was relatively unchanged from
best-in-class vehicles available in 2002. No change in drag coefficient for gasoline and
diesel engine powered vehicles was assumed. The frontal area is typical of 2002 model
year vehicles and was not varied within the comparison vehicle classes. Overall rolling
resistance, which represents the input of many components including tires, was typical of
vehicles sold in 2002.
Using estimates developed in conjunction with the cost comparison, the passenger car
weight difference between a gasoline and diesel engine powered vehicle was estimated to
be 93 Ibs.
Table 4 summarizes the vehicle level content assumptions for the comparison passenger car
vehicles with gasoline and diesel engines.
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Passenger Car
Engine displacement and configuration
Boost pressure
Maximum power (hp @ rpm)
Maximum torque (Ib-ft @ rpm)
Transmission
1 ^ gear ratio
2nd gear ratio
3rd gear ratio
4th gear ratio
Final drive ratio
Tire size
Vehicle test weight
Drag coefficient
Gasoline
2.4L I-4
0
1 57 @ 5600 rpm
1 62 @ 4000 rpm
4-speed auto
3.94
2.92
1.4
1
2.74
215/60R-16
3550 Ibs
0.28
Diesel
2.2L I-4
15 psi
1 33 @ 4000 rpm
250 @ 2000 rpm
4-speed auto
3.94
2.92
1.4
1
2.68
215/60R-16
3643 Ibs
0.28
Table 4. Passenger car comparative vehicle data
Table 5 summarizes the vehicle level content assumptions for the SUV vehicles. Using
estimates developed in conjunction with the cost comparison, the SUV weight difference
between a gasoline and diesel engine powered vehicle was estimated to be 180 Ibs.
SUV
Engine displacement and configuration
Boost pressure
Maximum power (hp @ rpm)
Maximum torque (Ib-ft @ rpm)
Transmission
1 ^ gear ratio
2nd gear ratio
3rd gear ratio
4th gear ratio
Final drive ratio
Tire size
Vehicle test weight
Drag coefficient
Gasoline
5LV8
0
232 @ 4000 rpm
380 @ 2500 rpm
4-speed auto
2.84
1.55
1
0.7
3.73
265/70R-17
5563 Ibs
0.41
Diesel
4LV8
15 psi
246 @ 4000 rpm
462 @ 2000 rpm
4-speed auto
2.84
1.55
1
0.7
3.43
265/70R-17
5743 Ibs
0.41
Table 5. SUV comparative vehicle data
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D. Cost and Weight Predictions
With reasonable predictions of the relative engine size and vehicle characteristics
necessary to achieve parity in performance, the vehicle level content for gasoline and diesel
engine versions was formed in detail. Assumptions for the relative technology content of
the engines were made using vehicle technology in mass production in 2002.
Using the vehicle information determined to achieve equivalent vehicle acceleration
performance, a detailed summary of the cost and weight differences between the gasoline
and diesel engine versions of the passenger cars and SUV's was prepared. The following
major areas account for most of the estimated cost and weight differences in the vehicles,
so a discussion of each system is detailed in the following sections.
• Engine, including engine mounted fuel injection system and turbocharger
• Vehicle fuel system, including evaporative emissions and ORVR systems
• Air induction system including intercooler for diesel engines
• Vehicle electrical system including battery and starter
• Powertrain mounting system
Cost estimates represent assumed relative production cost increases for diesel vehicles and
do not assume a "retail price equivalent" factor.
A detailed summary of the complete cost and weight comparisons for passenger car and
SUV vehicles is included in section D.8 as Table 9 (passenger car) and Table 10 (SUV).
D.1 Gasoline and Diesel Engine
The majority of the cost and weight difference between gasoline and diesel comparison is
the engine.
The majority of the cost penalty of the diesel engine is the fuel injection system. FEV
estimates that the cost difference between the gasoline fuel injection system and the diesel
fuel injection system is currently $735 for the passenger car and $1155 for the SUV. The
elimination of the gasoline engine ignition system and throttle body costs are relatively
small when compared to the overall diesel engine costs. Using the mature production
assumptions consistent with this study, the estimated cost difference for the diesel fuel
injection system is $465 and $735 for passenger car and SUV respectively.
Several factors contribute to the higher cost of the diesel fuel injection system. First and
most influential, a diesel fuel injection system must meter fuel directly into the
combustion chamber at high pressure. Typical automotive diesel fuel injection systems
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Page 12
operate with peak injection pressures of 1350 to 1600 bar (19,600 to 23,200 psi), while
gasoline port fuel injection systems typically operates with system pressures of 3 to 5 bar
(44 to 72 psi). The high pressure requirement for the diesel system requires the use of
more expensive high strength materials for all components and for the high pressure
connecting tubes to contain the fuel pressure.
The second factor that contributes to the higher cost of diesel fuel injection equipment is
the lack of feedback control of fuel quantity. Typical electronic gasoline fuel injection
systems operate using closed-loop control of fuel quantity through an oxygen sensor
mounted in the exhaust system. Opening and closing the throttle plate on a gasoline engine
adjusts the amount of air entering the engine. The amount of gasoline injected into the
cylinder can be electronically adjusted to achieve the correct air-fuel mixture properties.
The correct amount of fuel is metered and controlled with feedback depending on the
amount of oxygen measured in the exhaust stream. A diesel engine operates primarily
without a throttle; thus, the amount of air entering the cylinder is unregulated. The engine
output is regulated by the amount of fuel injected into the cylinder. Therefore, the system
must be deterministic in the amount of fuel injected. Accordingly, diesel fuel injectors are
manufactured under strict tolerances. Also, a diesel fuel injection system operates without
feedback control of fuel quantity.
A third factor that also contributes to the higher cost of diesel fuel injection equipment is
fundamentally related to the noise produced by a diesel engine. Conventional diesel
combustion noise is high because of a very high rate of cylinder pressure rise during the
initial combustion phase when the initial pre-mixed amount of fuel is quickly burned upon
auto-ignition. New common rail diesel fuel injection systems that are becoming extremely
popular with European consumers, have the capability to introduce more than one injection
event per cycle. With such a fuel injection system, an initial small injection quantity is
added to the combustion chamber early. A short time later, the main fuel charge is injected.
Because the early injection quantity is small, the initial combustion phase occurs more
slowly and the noise produced by the initial combustion is reduced. Proper control of the
tolerances of the quantity and relative timing of the early injection is critical to achieving
low noise and low exhaust emissions. The capability to provide multiple injection events
that occur close to each other also makes the diesel fuel injection system more expensive.
Further, the tolerances of the components that can reliably inject the necessary small fuel
injection quantity in a separate pulse add to the cost of the injector components.
Because the assumed common rail fuel injection system is a relatively new technology,
current production costs may reflect significant development and capitalization costs.
Further, the current market for light automotive common rail diesel fuel injection systems
currently has only four suppliers: Bosch, Siemens, Delphi, and Denso. Bosch currently
produces more systems than other suppliers in this rapidly growing market. As the market
for diesel fuel injection systems stabilizes, more competition may result. The fuel
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Page 13
injectors themselves, which account for dbout half of the price of the complete system,
may become more of a commodity just as gasoline port fuel injectors have become. Given
the boundary conditions of this study - mature products produced in large volumes by
several companies - FEV estimates that mature pricing for a diesel fuel injection system
may be reduced by 30% from the 2002 price estimate. Mature production cost estimates
use 2002 production cost estimates with 30% lower costs for the entire fuel injection
system.
Beyond the injection system, other factors add to the cost of the diesel engine. The base
mechanical engine represents a relatively small portion of the cost difference. As
summarized in Table 6, the base engine differences are estimated to add between $30 and
$40 to the cost of a diesel engine compared to a gasoline engine of similar output.
Other components that add cost to a diesel engine relative to a gasoline engine include the
turbocharger, EGR valve, and vacuum pump. The turbocharger is required on the diesel
engine to achieve competitive power density. For both comparison diesel engines in this
study, variable geometry turbochargers are assumed. Because currently variable geometry
turbochargers are in relatively low volume production, FEV also estimates that the
turbocharger production cost may be reduced in a more competitive market conditions
assumed by this study. FEV estimates that the turbocharger production cost may be reduced
30% compared to today's cost estimate.
To meet present NOx emissions standards in Europe or the US, a fast response, large flow
EGR system is necessary. For these comparison vehicles, the passenger car is assumed to
have a direct acting solenoid activated EGR valve with feedback control using a mass air
flow sensor. The SUV is also assumed to have such a valve, but because of the higher
vehicle weight, the SUV system should also include an EGR cooler. For both diesel
vehicles, a simple intake throttle valve is also required to provide intake-to-exhaust
manifold pressure drop to achieve high EGR rates. This EGR system content is typical of
vehicles with diesel engines to meet current 2002 emissions standards.
Because the diesel engine produces little if any vacuum, a pump is required to provide the
necessary vacuum to power the vacuum power-assisted brakes and provide a form of energy
to actuators in the vehicle Heating Ventilation Air Conditioning (HVAC) system and
vacuum modulated valves in the powertrain control system. For the purposes of this study,
vacuum assisted brakes and components are still assumed to be typical for the classes of
vehicle studied.
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Component
Cylinder block
Main bearing caps
Crankshaft
Main bearings
Connecting rods
Rod bearings
Piston
Rings
Cylinder head
Valvetrain
Piston cooling jets
Oil pump
Oil filter
Intake manifold
Vibration damper
Total, Base
Engine
Modifications for Base Diesel
Engine
Increased stiffness, provision for
piston cooling jets
Increase stiffness, better material
Increase stiffness, forged material
instead of cast iron for I-4 gasoline
engine
No change
Larger piston pin, tapered top
Premium material
Heavier
Increase stiffness, premium alloy
material
Reduced heat and engine speed
Necessary to cool piston
Larger capacity, lower engine
speed
Larger capacity
No injector mounting, simpler
design
Dual mode
Estimated
Incremental
1-4 Cost
(2002 $)
3
2
16
0
3
2
1
3
(3)
5
0
1
(2)
7
$38
Estimated
Incremental
V-8 Cost
(2002 $)
4
3
1
0
6
4
2
6
(4)
6
0
1
(4)
8
$33
Table 6. Base (mechanical) diesel engine component and cost difference
In this study the accessory drive is included in the engine assembly. Because the crankshaft
speed variations on a diesel engine are higher than on a gasoline engine, it is expected that
the alternator will require an over-running clutch for acceptable accessory drive belt
durability. Further, the belt and belt tensioner will be of higher material cost with larger
range of adjustment. The A/C compressor and power steering pump are not expected to
change in weight or cost for either engine. The alternator is not expected to change in
output.
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For the classes of vehicles considered, an acoustic engine cover is typically included on a
diesel engine to reduce cabin-level combustion and injector noise.
The gasoline engine must include an ignition system and throttle body, which are not
necessary on the diesel engine.
Using current estimates, the cost increase of a diesel engine for the passenger car
application vehicle is $910. For the SUV application, the cost penalty of the diesel engine
is estimated to be $1365. Under the boundary conditions of this study, the mature
production cost differences are estimated to be $586 and $870 for the passenger car and
SUV diesel engines respectively. Table 7 summarizes the primary contributors to the cost
difference between the gasoline and diesel engines for the passenger car application.
Component Modification for
Diesel Powertrain
Base engine mechanical
Fuel injection
Ignition
Turbocharger, variable geometry
Throttle body
Vacuum pump
EGR valve
Engine acoustic cover
Alternator (drive pulley clutch)
Accessory drive belt/tensioner
Total
Current
Estimated
Cost
Increment
(2002 $)
38
735
(75)
180
(27)
10
20
12
10
7
$910
Mature
Estimated
Cost
Increment
(2002 $)
38
465
(75)
126
(27)
10
20
12
10
7
$586
Table 7. Passenger car diesel engine component cost difference
A complete summary of the engine cost and weight differences for the comparison vehicles
is included in section D.8 as Table 9 (passenger car) and Table 10 (SUV).
D.2 Vehicle Fuel System
The vehicle fuel system for the gasoline engine includes an electric fuel pump with pre-
filter, a variable output fuel pump control system, evaporative emissions content including
carbon canisters to collect hydrocarbon vapors, and a purge valve to allow the engine to
consume any collected vapors. The diesel fuel injection system includes a mechanically
driven fuel pump; no electric fuel pump in the fuel tank is necessary on most diesel
systems. Further, because the fuel is less volatile, diesel engine powered vehicles are not
required to meet similar standards for evaporative emissions. Diesel engine powered
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EPA Contract 68-C-01-155 WA 0-2 FEV01-505P3 Rev. 1 Final Report
April 23, 2003
Page 16
vehicles are not required to meet Onboard Refueling Vapor Recovery (ORVR)
requirements of gasoline vehicles.
The diesel fuel filter is larger in capacity and must meet smaller filtration requirements
than for gasoline engines. The tighter requirements are necessary because of the closer
tolerances and higher loads of the diesel fuel injection equipment. A heated fuel filter is
not expected to be required.
Because the amount of fuel required to provide a vehicle with equivalent range is smaller
for a diesel, the tank volume can be reduced for a diesel passenger car. In this study, the
size of the fuel tank was changed to achieve the same vehicle range for gasoline and diesel
vehicles based on combined city/highway fuel economy predictions. The actual test weight
difference between the two vehicles was calculated using the higher density of diesel fuel,
smaller tank volume for the diesel, and assuming the fuel tank is half full at measured test
weight.
D.3 Air Induction System
The air induction system for the diesel engine includes an intercooler, which is vital to
achieving the power density of the turbocharged diesel engines. Because the Mass Air Flow
(MAP) sensor on the diesel engine is used for emissions-critical EGR control, the MAP
sensor for a diesel has a smaller tolerance band and higher cost than for a gasoline engine.
D.4 Powertrain Control System and Vehicle Electrical System
The relative complexity of the engine control system including the primary engine control
unit, sensors, and wiring is similar for both gasoline and diesel engines. A comparison of
the input/output devices for gasoline and diesel engines is made in Table 8.
The number of devices reveals that the relative complexity of the systems for gasoline and
diesel engines is nearly equivalent. It is FEV's opinion that the complexity of engine
management software and calibration effort needed for either engine can be considered
approximately equivalent.
The starter motor must be upsized to provide the rotation torque necessary to start a diesel
engine with a typical compression ratio of 18:1 compared to a compression ratio of
typically 10:1 for a gasoline engine. Along with the larger starter motor, the diesel engine
is also equipped with glow plugs to aid cold starting performance. Together, these two
features require a substantially larger battery to provide equivalent starting capability at low
ambient temperatures.
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EPA Contract 68-C-01-155 WA 0-2
FEV01-505P3 Rev. 1 Final Report
April 23, 2003
Page 17
Gasoline
Injectors (1 per cylinder)
Ignition (1 per cylinder)
Knock sensor
EGR valve
Mass Air Flow (MAP) sensor
Manifold Absolute Pressure (MAP)
sensor
Crank angle position sensor
Cam phase sensor
Fuel pressure sensor
Fuel pressure regulator
Coolant temperature sensor
Intake air temperature sensor
Exhaust gas oxygen sensor(s)
Catalyst monitor sensor(s)
None
Throttle position sensors (2)
None
None
Cooling fan controls
A/C compressor control
Diesel
Injectors (1 per cylinder)
None
Acoustic sensor (optional)
EGR valve
Mass Air Flow (MAP) sensor
Manifold Absolute Pressure (MAP)
sensor
Crank angle position sensor
Cam phase sensor
Fuel pressure sensor
Fuel pressure regulator
Coolant temperature sensor
Intake air temperature sensor
None
None
Fuel temperature sensor
Accelerator pedal sensors (2)
Atmospheric pressure sensor
Turbocharger actuator
Cooling fan controls
A/C compressor control
Table 8. Engine control unit input/output list
Catalyst monitors are required for OBD monitoring of gasoline engine catalysts. For the
SUV application, multiple catalysts (each with a monitoring sensor) are assumed. The
diesel vehicles are assumed not to require sensors to monitor the catalysts in the exhaust
system.
D.5 Powertrain Mounting System
Automotive diesel engines are typically turbocharged and operate at higher compression
ratios than gasoline engines. The engine structure is designed for higher peak cylinder
pressure levels that result from high boost pressure and high engine compression ratio.
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EPA Contract 68-C-01-155 WA 0-2 FEV01-505P3 Rev. 1 Final Report
April 23, 2003
Page 18
Further, a diesel engine also operates without the need for significant throttling. For all
these reasons, a diesel engine produces substantially higher engine shaking forces than a
gasoline engine of comparable configuration and output. To achieve similar vehicle level
noise and vibration levels with a diesel engine, it is therefore essential to enhance the
isolation performance of the powertrain mounting system with the diesel engine.
For the two vehicle comparisons in this study, FEV has assumed a relative step in
technology and isolation in the engine mounting system. Hydromounts are assumed for the
gasoline vehicles, while switchable hydromounts are assumed for the diesel vehicles. The
switching technology is available in mass-production in 2002 on several vehicles. Other
forms of active or semi-active engine mounts are available but not currently produced in
large volume.
D.6 Transmission and Drivetrain System
For the increased torque of the diesel engine, the transmission components are assumed not
to change dramatically. Within the vehicle simulation, only the final drive ratio was
changed for the diesel engine. FEV estimates that the transmission for the diesel engine
will be upgraded to handle the higher engine torque. Premium bearing materials, added
clutches to clutch packs with improved material, and upgraded gear surface treatment are
the only substantial changes assumed. No weight increase is expected for these changes.
The transmission cost increase associated with these upgrades is estimated to be $25 for
both vehicle classes in this study.
D.7 Other Contributors
To provide comparable noise and vibration levels in the passenger compartment, the sound
insulation package of the vehicle with a diesel engine will be upgraded. Higher density
foam and thicker insulation is necessary for critical areas.
Because the engine operates more efficiently, the diesel engine produces less passenger
compartment heating capacity. It is typical for vehicles with diesel engines to be equipped
with supplemental heaters to provide passenger compartment heat. For this study, a
supplemental coolant heater is assumed for both diesel vehicles. It is FEV's experience
that such devices are necessary to meet federal requirements for windshield defrost time,
and to meet consumer expectations. For the passenger car, an electric resistance heater in
line with the coolant supply to the heater core is assumed. For the larger passenger volume
of the SUV, a large supplemental heater that combusts fuel to provide increased heat to the
coolant is assumed. The cost of these devices is estimated to be $15 for the passenger car
and $50 for the SUV.
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EPA Contract 68-C-01-155 WA 0-2 FEV01-505P3 Rev. 1 Final Report
April 23, 2003
Page 19
The diesel and gasoline engine exhaust systems are assumed to be nearly equivalent in
content and cost for similar production volumes.
Because the engine heat rejection is somewhat less, the radiator can be modestly downsized
for the diesel engine. Other cooling system content is assumed equivalent.
D.8 Cost and weight prediction summary
The predicted weight difference between gasoline and diesel vehicles was estimated and
used in the vehicle simulation model to assess the vehicle performance. The cost
differential between gasoline and diesel vehicles is summarized in Table 9 (passenger car)
and Table 10 (SUV).
In both classes of vehicles, the primary cost and weight increase is due to the diesel engine
itself.
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EPA Contract 68-C-01-155 WA 0-2
FEV01-505P3 Rev. 1 Final Report
April 23, 2003
Page 20
Component
Engine
Air Induction
Exhaust
Transmission
Engine
Electronic
Control and
Vehicle
Electrical
System
Powertrain
Mounting
System
Cooling System
Body
HVAC System
Chassis Fuel
System
Totals
Modifications for Diesel
Powertrain
Sum
Base engine
Fuel injection
Ignition
Turbocharger, variable geometry
Throttle body
Vacuum pump
EGR valve
Engine acoustic cover
Alternator (drive pulley clutch)
Accessory drive belt/tensioner
Sum
Intercooler and ducts
MAF sensor
Sum
Sum
Sum
Engine electronic control unit
Exhaust gas oxygen sensor(s)
Battery, larger for diesel
Starter, 2 kW for diesel
Glow plugs / relay
Sum
Mounts, switchable hydromounts
Vacuum control valves, hoses
Sum
Radiator
Sum
NVH package
Sum
Supplemental coolant heater
Sum
Fuel tank, mounting
Electric fuel supply pump, controller
Fuel filler and cap
Evaporation canisters / valves
Fuel filter
ORVR requirements
Current
Estimated
Cost
Increment
(2002 $)
$910
38
735
(75)
180
(27)
10
20
12
10
7
$55
50
5
$0
$25
$20
0
(30)
15
20
15
$107
100
7
($4)
$10
$15
($75)
(10)
(40)
(2)
(25)
4
(6)
$1063
Mature
Estimated
Cost
Increment
(2002 $)
$586
38
465
(75)
126
(27)
10
20
12
10
7
$55
50
5
$0
$25
$20
0
(30)
15
20
15
$107
100
7
($4)
$10
$15
($75)
(10)
(40)
(2)
(25)
4
(6)
$739
Estimated
Weight
Increment
(Ibs)
66 Ib
11 Ib
Qlb
Qlb
19 Ib
1 Ib
Olb
11 Ib
lib
(16lb)
93 Ib
Table 9. Passenger car production cost and weight increments for diesel
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EPA Contract 68-C-01-155 WA 0-2
FEV01-505P3 Rev. 1 Final Report
April 23, 2003
Page 21
Component
Engine
Air Induction
Exhaust
Transmission
Engine
Electronic
Control and
Vehicle
Electrical
System
Powertrain
Mounting
System
Cooling System
Body
HVAC System
Chassis Fuel
System
Total
Modifications for Diesel
Powertrain
Sum
Base engine
Fuel injection system
Ignition system
Turbocharger, variable geometry
Throttle body
EGR cooler
Vacuum pump
EGR valve
Engine acoustic cover
Alternator (drive pulley clutch)
Accessory drive belt/tensioner
Sum
Intercooler and ducts
MAF sensor
Sum
Sum
Transmission
Sum
Engine electronic control unit
Exhaust gas oxygen sensor(s)
Battery, larger for diesel
Starter, 3 kW for diesel
Glow plugs / relay
Sum
Mounts, switchable hydromounts
Vacuum control valve, hoses
Sum
Radiator
Sum
NVH package
Sum
Supplemental coolant heater
Sum
Fuel tank, mounting
Electric fuel supply pump
Fuel filler and cap
Evaporation canisters / valves
Fuel filter
ORVR requirements
Current
Estimated
Cost
Increment
(2002 $)
$1365
33
1155
(120)
250
(33)
20
10
20
12
10
8
$80
75
5
$0
$25
$12
0
(60)
25
20
27
$87
80
7
($13)
$25
$50
($94)
(13)
(55)
(2)
(30)
6
(8)
$1537
Mature
Estimated
Cost
Increment
(2002 $)
$870
33
735
(120)
175
(33)
20
10
20
12
10
8
$80
75
5
$0
$25
$12
0
(60)
25
20
27
$87
80
7
($13)
$25
$50
($94)
(13)
(55)
(2)
(30)
6
(8)
$1042
Estimated
Weight
Increment
132lb
11 Ib
Olb
21 Ib
17 Ib
2Jb
Olb
12 Ib
8lb
(23 Ib)
180 Ib
Table 10. SUV production cost and weight increments for diesel
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EPA Contract 68-C-01-155 WA 0-2
E. Results
FEV01-505P3 Rev. 1 Final Report
April 23, 2003
Page 22
FEV performed simulation of two representative vehicles to assess the fuel consumption
and performance difference for diesel engines compared to baseline gasoline engines.
Simulation models of vehicles with gasoline engines were adapted to include diesel
engines. Along with the engine, the final drive ratio was optimized, and the vehicle weight
was increased. The required peak engine performance necessary to achieve performance
parity with the gasoline vehicle was determined.
The weight increase from a diesel powertrain was estimated using detailed summaries of
the component differences shown in Tables 9 and 10 in Section D.8. The primary
contributor to the increase in vehicle weight is the diesel engine itself. Other components
including the battery and starter are also considered.
Fuel economy and performance of the vehicles with gasoline and diesel engines were
compared using the simulation model. Results are summarized in Table 11 for the
passenger car and Table 12 for the SUV. For both vehicle classes with equivalent zero to 60
mile per hour acceleration, the combined fuel economy in miles per gallon improved by
about 40% with the diesel engine.
Passenger Car
Vehicle Weight (test)
0-60 mph Acceleration
City Fuel Economy
Highway Fuel Economy
Combined Fuel Economy
30-50 mph Acceleration
50-70 mph Acceleration
Top Speed
55 mph Steady State Fuel Economy
Current Production Cost Estimate (2002 $)
Mature Production Cost Estimate (2002 $)
Gasoline
3550 Ibs
1 1 .5 sec
24.8 mpg
41.0 mpg
30.2 mpg
4.8 sec
9.8 sec
1 33 mph
44.9 mpg
Baseline
Baseline
Diesel
3643 Ibs
1 1 .5 sec
36.7 mpg
51.3 mpg
42.1 mpg
5.8 sec
7.3 sec
1 22 mph
49.8 mpg
+ $1063
+ $739
Table 11. Passenger car comparative results
The cost increase from a diesel powertrain was estimated using detailed summaries of the
component differences shown in Tables 9 and 10 in Section D.8. The primary contributor
to the increase in vehicle cost is the diesel engine itself.
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EPA Contract 68-C-01-155 WA 0-2
FEV01-505P3 Rev. 1 Final Report
April 23, 2003
Page 23
SUV
Vehicle Weight (test)
0-60 mph Acceleration
City Fuel Economy
Highway Fuel Economy
Combined Fuel Economy
30-50 mph Acceleration
50-70 mph Acceleration
Top Speed
55 mph Steady State Fuel Economy
Current Production Cost Estimate (2002 $)
Mature Production Cost Estimate (2002 $)
Gasoline
5563 Ibs
1 0.3 sec
14.7 mpg
21.0mpg
17.0 mpg
4.5 sec
1 5.3 sec
119 mph
19.9 mpg
Baseline
Baseline
Diesel
5743 Ibs
1 0.3 sec
21.4 mpg
28.1 mpg
24.0 mpg
4.8 sec
1 5.0 sec
119 mph
27.5 mpg
+ $1537
+ $1042
Table 12. SUV comparative results
The current estimated production cost of the common rail fuel injection system on the
diesel engine was estimated for both vehicle classes. Because some current technology is
new and the production volumes are rapidly growing, the current system prices may fall
significantly as market competition increases. The production cost of gasoline port fuel
injectors fell as the number of suppliers and market penetration increased. FEV estimates
that a 30% reduction in common rail diesel fuel injection total system cost could be
achieved under the boundary conditions of this study. FEV further estimates that the
production cost of a variable geometry turbocharger may also be sensitive to market
competition. A reduction in production cost of 30% was estimated for the turbocharger
component on both vehicles. With these assumptions, estimates of the diesel powertrain
system costs were made.
The cost increment for the diesel powertrain is also summarized for passenger car and SUV
in Tables 11 and 12 using current cost estimates and mature cost estimates.
Based on direction from the EPA Project Officer, the relative cost and weight differences
of exhaust aftertreatment systems for gasoline and diesel vehicles are not included in this
study.
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EPA Contract 68-C-01-155 WA 0-2 FEV01-505P3 Rev. 1 Final Report
April 23, 2003
Page 24
F. Appendix A-References
1 National Automobile Dealers Association, 2002 NADA Data
2 USA Today, May 15, 2001, "Diesel-Sippers Win Fans as Gas Prices Soar"
3 VDA (Verband der Automobilindustrie e.V.) Auto 2002 Annual Report
-------
APPENDIX J
Appendix J: FEV Report - Variable Compression Ratio and
Variable Displacement Engine Cost
This appendix contains a report written by FEV to estimate the costs for a variable compression
ratio engine and a variable displacement engine.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page J-l
-------
Appendix J
Engine Technology
Draft Report Rev. 2 FEV02-622F
Variable Compression Ratio and
Variable Displacement Engine Cost
Engine and Vehicle Development with Production Intent
Contract No. 68-C-02-036
Work Assignment 0-1
Development of Various Unique Engines
Prepared for:
Jeff Alson and Tom Bejma
U.S. Environmental Protection Agency
2000 Traverwood Drive
Ann Arbor, Ml 48105
Submitted by:
Tom Casciani
FEV Engine Technology, Inc.
4554 Glenmeade Lane
Auburn Hills, Ml 48326
January 29, 2003
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EPA Contract No. 68-C-02-036 WA 0-1 Draft Report Rev. 2 FEV02-622F
January 29, 2003
Page ii
Table of Contents
A. Introduction and Program Objectives
B. Methodology
B.1 Variable Compression Ratio Engine
B.2 Variable Displacement Engine
C. Results
D. Recommendations
-------
Variable Compression Ratio and Variable Displacement Engine Cost
A. Introduction and Program Objectives
EPA has utilized FEV to provide design concepts for Variable Compression Ratio
(VCR) and variable displacement engines under previous EPA contracts. The
objective of this project was to conduct additional analysis to estimate the
incremental cost of each concept applied to the base engines utilized in FEV's
study titled Cost and Fuel Economy Comparison of Diesel and Gasoline
Powertrains in Passenger Cars and Light Trucks submitted under contract
68-C-01-155WAO-2.
The VCR concept has been incorporated into a 2-cylinder Boxer engine utilizing a
piston within a piston design, which is hydraulically actuated and incorporated into
a 70 mm diameter bore, under previous contract work scopes. Components have
been designed, fabricated and initial development testing performed for this
application, which provides the component designs as shown in Figure A.1 for the
VCR cost study. The variable displacement engine concepts were developed as a
twin crankshaft concept of a V-8 engine as shown in Figure A.2, as the basic
architecture for a family of variable displacement Twin Crank engines ranging from
6-cylinders to 12-cylinders.
The technical details of both concepts are contained in previous reports and
presentations. This report addresses the cost aspects.
Figure A.1: Component Designs for the VCR Cost Study
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EPA Contract No. 68-C-02-036 WA 0-1
Draft Report Rev. 2 FEV02-622F
January 29, 2003
Page 2
y* of
Figure A.2: Variable Displacement Twin Crank V-8 Engine Concept
B. Methodology
The cost estimates were performed using the following methodology and are
based on a production volume of 250,000 units annually:
1. Each affected component was reviewed and a percentage increment was
estimated for material and processing cost, i.e., 5% decrease in raw casting
cost and 15% increase in machining cost. The incremental change in
assembly and subassembly cost was also estimated.
2. Using a detailed production engine cost bill of material (from another program)
the percent increments were calculated as dollar values.
3. The same detailed engine cost bill of material was feature-normalized to the
base engine being used in the Cost and Fuel Economy Comparison of Diesel
and Gasoline Powertrains in Passenger Cars and Light Trucks report and the
total engine cost so adjusted.
4. The final cost differential was calculated by multiplying the cost from Step 2 by
the ratio of the adjusted detail cost from Step 3 to the cost of the base engine
used in the Cost and Fuel Economy Comparison of Diesel and Gasoline
Powertrains in Passenger Cars and Light Trucks report.
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EPA Contract No. 68-C-02-036 WA 0-1
Draft Report Rev. 2 FEV02-622F
January 29, 2003
Page 3
B.1 Variable Compression Ratio Engine
The cost estimate uses a 2.4L I-4 engine typified by a Toyota Camry. The
cost includes weight added to the balance shafts to compensate for the
increased piston weight. The cost increase should be doubled for a
5.0 L V-8 engine, although balance shafts are not required, additional
weight would be required on the crankshaft counterweight and the
crankcase would be expanded for the larger counterweights. Details of the
costing are listed in Table B.1.1. Additional costs for high pressure oil
supply, control actuators and electronics were not included in the total costs.
VCR Piston in Piston
Outer Piston
Inner Piston
Small Piston Pins
Forked Connecting Rod
Piston Pin
Actuating Cam
Springs
Fasteners
Oil Passages
Material cost, 70% of same size production piston
Machining cost, 50% increase over standard piston
Hard coat inside bore, 20% increase in finished cost
Material, aluminum
Material and machining cost, same as production piston of same size
Add 10% for skirt coating
Add inner piston rings and spring washer
With retention feature, both pins same as one large pin
Material, forged solid 25% increase
Machining, forked end and oil drilling 150% increase
2 partial bushings, 50% over single bushing
Material, 15% increase
Machining, 300% increase
Add powder metal parts, cost/cam same as oil pump rotor set
Bushing, same as conn rod pin bushing
50% cost of valve spring each
6 pins, clips, keys = $0.60
Rod and main bearings - add cost difference between upper and lower to each
Block, add 2% to casting cost and 10% to machining cost
Crank, add 15% to machining cost
Not Costed:
:ontrol Valve
High Pressure Oil Supply
Integration into Block
Table B.1.1: Component Cost Considerations-Variable Compression Ratio
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EPA Contract No. 68-C-02-036 WA 0-1
Draft Report Rev. 2 FEV02-622F
January 29, 2003
Page 4
B.2 Variable Displacement Engine:
The cost estimate was conducted for a 5.0L Twin Crank V-8 engine. Details
of the costing are listed in Table B.2.1. The output gear drive, clutches,
accessory drive, modified starter and electronics control module were not
included being specific to the power output arrangement. A suitable strategy
for a variable displacement Twin Crank 4-cylinder engine has not be
identified due to balance issues, therefore no cost estimates were
performed for this option. Concept designs have been completed for a Twin
Crank 6-cylinder, 10-cylinder, and 12-cylinder engine but were not costed
for this study.
Twin Crank
Cylinder block
Main bearing caps
Crankshaft
Timing drive
Front cover
Crank seals
Flywheel
Oil pan
Oil pump
Intake manifold
Sensors
Engine wiring
Engine assembly
Casting add 12% due to weight increase
Machining add 15% for oil gallery, added caps, and misc. fasteners
Add 5 caps plus fasteners plus 100%
Replace V-8 with 2 4's plus 90% material and 80% machining
Crank sprocket plus 100%
Tensioner plus 100%
2 short chains instead of long chain plus 75%
Larger plus 10% material
Front and rear plus 100%
Add one plus 100%
Larger and more fasteners plus 20%
Replace with 2 smaller plus 90%
Oil pickup plus 100%
Two 4's replace one 8, plus 40% material and 80% machining
Add throttle body plus 80%
Crank plus 100%
Cam plus 100%
Oil pressure plus 100%
Plus 40%
Plus 35%
Table B.2.1: Component Cost Considerations-Twin Crank V-8 Engine
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EPA Contract No. 68-C-02-036 WA 0-1
Draft Report Rev. 2 FEV02-622F
January 29, 2003
Page 5
C. Results
The incremental costs for the VCR 2.4L I-4 engine are summarized in Table C.1.
The cost includes $45.55 for modifications to existing components and $43.24 for
new additional components totaling $88.79. A VCR 5.0L V-8 engine would be
twice this amount totaling $177.58.
Modified Parts
Pistons (4)
Piston pins (4)
Cylinder block
Crankshaft
Balance shafts (2)
Sub Total
Cost
$21.60
$2.70
$9.06
$9.19
$3.00
$45.55
Added Parts
Inner pistons (4)
Small piston pins (4)
Inner piston rings (4 sets)
Springs (4 sets)
Actuating cams (4)
Fasteners (4 sets)
Actuating cam bushings (4)
Sub Total
Total
Cost
$25.00
$3.40
$2.52
$0.96
$10.00
$0.60
$0.76
$43.24
$88.79
Table C.1: Incremental Cost - 4-cylinder VCR Engine
The incremental costs for the variable displacement Twin Crank 5.0L V-8 Engine
are summarized in Table C.2. The cost includes $102.85 for modifications to
existing components and $174.99 for new additional components totaling $277.84.
Modified Parts
Engine assembly
Timing belt cover
Cylinder block
Oil pan and gasket
Engine wiring
Crankshaft
Sub Total
Cost
$47.18
$3.37
$36.79
$3.82
$22.44
($10.75)
$102.85
Added Parts
Crankshaft sprocket
Cam sensor
Crankshaft bearing caps
Main bearings
Crankshaft
Crankshaft vibration damper
Crankshaft & camshaft seals
Sub Total
Total
Cost
$1.17
$6.91
$16.34
$5.19
$122.43
$10.10
$12.85
$174.99
$277.84
Table C.2: Incremental Cost - Twin Crank V-8 Engine
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EPA Contract No. 68-C-02-036 WA 0-1
Draft Report Rev. 2 FEV02-622F
January 29, 2003
Page 6
Figure C.1 from the EPA shows the inclusion of the conventional
mechanical power output option for the variable displacement Twin Crank
5.0L V-8 Engine. This option would add $53.40 (or $153.40 with the
control system), to the total cost. Table C.3 shows a breakdown of the
components.
72
13
Figure C.1: Conventional Mechanical Power Output Option
Conventional
Output one-way clutch
Output gearx 2
Flywheel with ring gear
Added starter cost
Larger flywheel housing
Sub Total
Control System
Total
Cost
$9.00
$16.00
$8.00
$18.00
$2.40
$53.40
$100.00
$153.40
Table C.3: Incremental Cost - Twin Crank V-8 Engine
Conventional Option
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EPA Contract No. 68-C-02-036 WA 0-1
Draft Report Rev. 2 FEV02-622F
January 29, 2003
Page 7
Figure C.2 from the EPA shows the variable displacement Twin Crank
5.0L V-8 Engine for the hydraulic hybrid application incorporating two (2)
hydraulic units. Each hydraulic unit is assumed to be capable of
withstanding crankshaft loads, therefore eliminating the need for two (2)
intermediate bearing assemblies. This option would add $28.30 (or
$128.30 with the control system), to the total cost. Table C.4 shows a
breakdown of the components.
\\ \
IS 32 23 24
13 ,4
Figure C.2: Hydraulic Hybrid Option
Hydraulic Hybrid
Flywheel with ring gear
Added starter cost
Block additions/fasteners
Sub Total
Control System
Total
Cost
$8.00
$18.00
$2.30
$28.30
$100.00
$128.30
Table C.4: Incremental Cost - Twin Crank V-8 Engine
Hydraulic Hybrid Option
-------
EPA Contract No. 68-C-02-036 WA 0-1 Draft Report Rev. 2 FEV02-622F
January 29, 2003
Page 8
D. Recommendations
The incremental costs provided in this analysis are estimates based on actual
manufactured costs of comparable components. Additional accuracy can be
realized with costing obtained from production suppliers and completion of detailed
designs for the Twin Crank Engine concept.
-------
APPENDIX K
Appendix K: Price Factors: Price per Unit Weight by
Component System
As discussed in Section 6, the manufacturing cost of each hardware component is estimated from
the weight of the component multiplied by price per unit weight. The price per unit weight
varies depending on the complexity of manufacturing the component. Appendix K gives the
source data used to derive the complexity price factors. There are three major price per weight
figures used in this analysis, based on components that are used in three major vehicle
subsystems: transmission, engine, and chassis. Price per weight values for these three vehicle
subsystems were derived using cost data from a typical 1990 Big-Three vehicle adjusted to 2002
costs. Table K-l gives the original cost by component for the 1990 vehicle. Further explanation
of the development of the price factors is discussed in Section 6.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page K-l
-------
APPENDIX K
Table K-1
Vehicle Manufacturing Costs
1990Car-V6, 3.0L, 4 Speed Auto, Fl, FWD
Subsystem
Body
Body in White
Howlnt&Ext
Elect. Components
Molding Panels
Trim & Insulation
Seats
Glass
Safety Equipment
Coatings
Total Body
Engine
Base Engine
Engine Comp. Access
Eng. Assembly
Total Engine
Transmission
Clutch & Controls
Transmission
Trans Assembly
Total Transmission
Chassis
Eng Electrical
Fl Emission System
Final Drive
Frame
Suspension
Steering
Brakes
Wheels/Tires/ Tools
Exhaust
Catalytic Converter
Fuel System
Fender Shields Bumper
Chassis Elect Battery
Fluids
Accessories Equip.
Total Chassis
Vehicle Assembly
Total Vehicle
Finished
Wt(lbs)
826
33
23
30
207
107
81
21
10
1338
444
160
0
604
6.5
134
0
141
38
30
110
99
153
60
154
181
33
30
24
90
41
115
4
1162
0
3245
Material
Used
926
33
23
33
210
110
81
21
10
1447
464
180
0
644
8
140
0
148
38
32
115
110
160
65
160
190
35
33
27
93
41
115
4
1218
0
3457
Cost/
Pound
$0.40
$0.42
$0.78
$1.10
$1.00
$1.10
$1.10
$1.00
$0.50
$7.40
$0.60
$0.40
$0.00
$1.00
$0.40
$0.40
$0.00
$0.80
$0.75
$3.00
$0.40
$0.32
$1.40
$0.40
$0.55
$0.55
$0.60
$3.00
$0.30
$0.90
$0.30
$0.70
$1.10
$14.27
$0.00
$23.47
Material
Costs
$370.40
$13.86
$17.94
$36.30
$210.00
$121.00
$89.10
$21.00
$5.00
$884.60
$278.40
$72.00
$0.00
$350.40
$3.20
$56.00
$0.00
$59.20
$28.50
$96.00
$46.00
$35.20
$224.00
$26.00
$88.00
$104.50
$21.00
$99.00
$8.10
$83.70
$12.30
$80.50
$4.40
$957.20
$0.00
$2,251.40
Labor
Hours
10.84
0.59
0.52
0.37
4.03
1.73
1.37
0.55
0.07
20.07
13.11
2.40
6.00
21.51
0.05
4.30
3.47
7.82
0.53
0.70
1.52
1.30
2.00
1.17
3.20
6.40
1.40
0.60
0.50
1.80
1.76
2.70
0.10
25.68
35.00
110.08
Labor
Rate
$9.50
$9.51
$9.50
$9.51
$9.50
$9.50
$9.50
$9.51
$9.57
$9.50
$9.50
$9.50
$9.50
$9.50
$9.60
$9.50
$9.50
$9.50
$9.51
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
$9.50
Labor
Cost
102.98
5.61
4.94
3.52
38.29
16.44
13.02
5.23
0.67
$190.70
$124.55
$22.80
$57.00
$204.35
$0.48
$40.85
$32.97
$74.30
$5.04
$6.65
$14.44
$12.35
$19.00
$11.12
$30.40
$60.80
$13.30
$5.70
$4.75
$17.10
$16.72
$25.65
$0.95
$243.97
$332.50
$1,045.82
Overhead
Labor Rate
250%
1 00%
1 00%
1 50%
1 50%
1 50%
200%
100%
200%
250%
1 50%
250%
150%
150%
250%
1 00%
1 00%
150%
150%
1 50%
1 50%
1 50%
200%
1 00%
250%
150%
1 50%
1 00%
150%
1 50%
250%
Overhead
Labor Cost
$257.45
$5.61
$4.94
$5.28
$57.44
$24.66
$26.04
$5.23
$1.34
$387.99
$311.38
$34.20
$142.50
$488.08
$0.72
$61.28
$82.43
$144.42
$5.04
$6.65
$21.66
$18.53
$28.50
$16.68
$45.60
$121.60
$13.30
$14.25
$7.13
$25.65
$16.72
$38.48
$1.43
$381.20
$831.25
$2,232.93
Total
Labor Cost
$360.43
$11.22
$9.88
$8.80
$95.73
$41.10
$39.06
$10.46
$2.01
$578.69
$435.93
$57.00
$199.50
$692.43
$1.20
$102.13
$115.40
$218.72
$10.08
$13.30
$36.10
$30.88
$47.50
$27.80
$76.00
$182.40
$26.60
$19.95
$11.88
$42.75
$33.44
$64.13
$2.38
$625.17
$1,163.75
$3,278.75
Total
Mfr Cost
$730.83
$25.08
$27.82
$45.10
$305.73
$162.10
$128.16
$31.46
$7.01
$1,463.29
$714.33
$129.00
$199.50
$1,042.83
$4.40
$158.13
$115.40
$277.92
$38.58
$109.30
$82.10
$66.08
$271.50
$53.80
$164.00
$286.90
$47.60
$118.95
$19.98
$126.45
$45.74
$144.63
$6.78
$1,582.37
$1,163.75
$5,530.00
Total
Div. Cost
$2,268
$1,616
$431
$2,453
$1,803
$8,571
MSRP $12,944
Tecnology improvement incremental Cost Analysis , Easton Consultants for
Committee on Fuel Economy of Automobiles and L ght Trucks Workshop, July 1991
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page K-2
-------
APPENDIX L
Appendix L: Incremental Cost Calculations by Technology
Scenario
Appendix L provides the detailed incremental cost data for each of the 40 technology scenarios
considered in the body of this report. There is one table for each technology. Each of the tables
in the Appendix provides the list of components added or subtracted from the base vehicle
technology to form the new technology. For each listed component within a technology, the
component weight in kg, the price per kg, the supplier price and the retail price equivalent (RPE)
is given. The weight and price of components whose function is replaced by other hardware are
noted in red as subtractions from the incremental cost calculation. The net change in cost is the
total incremental cost provided near the bottom of each table. The total incremental costs of the
technology along with the change in fuel economy and brake savings are used in the calculation
of payback and vehicle lifetime savings.
Similar tables for the sensitivity case with reduced roadload have not been provided in the report.
As discussed in Appendix A, the cost of reducing roadload by 20% is estimated to be $210 for
all the technologies. There is no need to recreate all these tables for the simple addition of $210
to the total incremental cost of each technology.
Tables Ll-1 through LI-20 contain cost data for SUV configurations.
Tables L2-1 through L2-20 contain cost data for Car configurations.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page L-l
-------
Table L1-1: Base Case Incremental Cost
4WD SUV Gas, Conventional Transmission
Component
Totals
Weight
(kg)
0.0
Price Factor
($ per kg)
Supplier
Price
$0
Table L1-2: Incremental Cost
4WD SUV Clean Diesel
Component
cost increase for diesel engine
net downsize of fuel tank
Totals
Weight
(kg)
81.6
81.6
Price Factor
($ per kg)
-
$7.19
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$1 ,324
$0
$1,324
$1,668
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-3: Incremental Cost
4WD SUV Gas, Variable Displacement
Component
cost increase for variable displacement engine
net downsize of fuel tank
Totals
Weight
(kg)
43.1
-1.2
41.9
Price Factor
($ per kg)
-
$7.19
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$431
-$9
$422
$532
Calculation of fuel tank downsize
fuel efficiency improvement
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
fuel tank size (gals)
fuel tank weight (kg)
(included above)
14.1%
14.63
0.0684
16.69
0.0599
-12.4%
Initial Final
28.0 24.5
10.0 8.7
full tank
delta
(3.5)
(1.23)
Table L1-4: Incremental Cost
4WD SUV Clean Diesel, Variable Displacement
Component
cost increase for diesel engine
cost increase for variable displacement engine
net downsize of fuel tank
Totals
Weight
(kg)
81.6
43.1
-3.6
121.2
Price Factor
($ per kg)
$7.19
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$1 ,324
$431
-$13
$1,742
$2,195
Calculation of fuel tank downsize
fuel efficiency improvement
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
fuel tank size (gals)
fuel tank weight (kg)
(included above)
55.4%
14.63
0.0684
22.74
0.0440
-35.6%
Initial Final
28.0 18.0
10.0 6.4
full tank
delta
(10.0)
(3.56)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-5: Incremental Costs
4WD SUV Gas, Mild Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
1 .4 gearset integrated into transfer case
Complexity Level #2 (like an Engine)
1 10 cc pump motor (w/mounting flange for transfer case)
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
pump motor isolation mount (in addition to transfer case mount)
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
7 gal composite accumulator (high pressure)
7 gal composite accumulator (low pressure)
Totals
Weight
(kg)
3.5
37.7
-1.1
8.1
8.5
4.5
1.0
16.9
32.3
14.3
125.8
Price Factor
(per kg)
$10.45
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$37
$343
-$8
$58
$61
$33
$7
$51
$323
$143
$1,048
$1,321
Calculation of fuel tank downsize (included above)
fuel efficiency improvement] 12.1% |
base mpg 14.63
base consumption (gpm) 0.0684
improved mpg 16.40
improved consumption (gpm) 0.0610
consumption reduction -10.8%
Initial
Final
full tank
delta
fuel tank size (gals)
fuel tank weight (kg)
28.0
25.0
8.9
(3.0)
(1.08)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-6: Incremental Costs
4WD SUV Clean Diesel, Mild Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
1 .4 gearset integrated into transfer case
Complexity Level #2 (like an Engine)
cost increase for diesel engine
1 10 cc pump motor (w/mounting flange for transfer case)
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
pump motor isolation mount (in addition to transfer case mount)
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
7 gal composite accumulator (high pressure)
7 gal composite accumulator (low pressure)
Totals
Weight
(kg)
3.5
81.65
37.7
-3.6
8.1
8.5
4.5
1.0
16.9
32.3
14.3
204.9
Price Factor
(per kg)
$10.45
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$37
$1,324
$343
-$13
$58
$61
$33
$7
$51
$323
$143
$2,367
$2,983
Calculation of fuel tank downsize (included above)
fuel efficiency improvement] 55.4% |
base mpg 14.63
base consumption (gpm) 0.0684
improved mpg 22.74
improved consumption (gpm) 0.0440
consumption reduction -35.6%
Initial
Final
full tank
delta
fuel tank size (gals)
fuel tank weight (kg)
28.0
10.0
18.0
6.4
(10.0)
(3.56)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-7: Incremental Costs
4WD SUV Gas, Variable Displacement, Mild Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
1 .4 gearset integrated into transfer case
Complexity Level #2 (like an Engine)
cost increase for variable displacement engine
1 10 cc pump motor (w/mounting flange for transfer case)
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
pump motor isolation mount (in addition to transfer case mount)
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
7 gal composite accumulator (high pressure)
7 gal composite accumulator (low pressure)
Totals
Weight
(kg)
3.5
43.09
37.7
-2.2
8.1
8.5
4.5
1.0
16.9
32.3
14.3
167.7
Price Factor
(per kg)
$10.45
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$37
$406
$343
-$16
$58
$61
$33
$7
$51
$323
$143
$1,446
$1,822
Calculation of fuel tank downsize (included above)
fuel efficiency improvement| 29.0% |
base mpg 14.63
base consumption (gpm) 0.0684
improved mpg 18.87
improved consumption (gpm) 0.0530
consumption reduction -22.5%
Initial
Final
full tank
delta
fuel tank size (gals)
fuel tank weight (kg)
28.0
10.0
21.7
7.7
(6.3)
(2.24)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-8: Incremental Costs
4WD SUV Clean Diesel, Variable Displacement, Mild Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
1 .4 gearset integrated into transfer case
Complexity Level #2 (like an Engine)
cost increase for diesel engine
cost increase for variable displacement engine
1 10 cc pump motor (w/mounting flange for transfer case)
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
pump motor isolation mount (in addition to transfer case mount)
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
7 gal composite accumulator (high pressure)
7 gal composite accumulator (low pressure)
Totals
Weight
(kg)
3.5
81.65
43.09
37.7
-4.3
8.1
8.5
4.5
1.0
16.9
32.3
14.3
247.2
Price Factor
(per kg)
$10.45
-
-
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$37
$1,324
$406
$343
-$18
$58
$61
$33
$7
$51
$323
$143
$2,768
$3,487
Calculation of fuel tank downsize (included above)
fuel efficiency improvement| 77.2% |
base mpg 14.63
base consumption (gpm) 0.0684
improved mpg 25.92
improved consumption (gpm) 0.0386
consumption reduction -43.6%
Initial
Final
full tank
delta
fuel tank size (gals)
fuel tank weight (kg)
28.0
10.0
15.8
5.6
(12.2)
(4.35)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-9: Incremental Costs
4WD SUV Gas, Mild Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
1 .4 gearset integrated into transfer case
Complexity Level #2 (like an Engine)
1 10 cc pump motor (w/mounting flange for transfer case)
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
Initial fuel tank size (gals)
pump motor isolation mount (in addition to transfer case mount)
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
Battery upsize
7 gal composite accumulator (high pressure)
7 gal composite accumulator (low pressure)
Totals
Weight
(kg)
3.5
37.7
-1.3
8.1
8.5
4.5
1.0
16.9
5.2
32.3
14.3
130.7
Price Factor
(per kg)
$10.45
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$3.00
$2.70
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$37
$343
-$10
$58
$61
$33
$7
$51
$14
$323
$143
$1,060
$1,336
Calculation of fuel tank downsize (included above)
fuel efficiency improvement] 15.3% |
base mpg 14.63
base consumption (gpm) 0.0684
improved mpg 16.87
improved consumption (gpm) 0.0593
consumption reduction -13.3%
Initial
Final
full tank
delta
fuel tank size (gals)
fuel tank weight (kg)
28.0
10.0
24.3
8.7
(3.7)
(1.32)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-10: Incremental Costs
4WD SUV Clean Diesel, Mild Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
1 .4 gearset integrated into transfer case
Complexity Level #2 (like an Engine)
cost increase for diesel engine
1 10 cc pump motor (w/mounting flange for transfer case)
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
pump motor isolation mount (in addition to transfer case mount)
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
Battery upsize
7 gal composite accumulator (high pressure)
7 gal composite accumulator (low pressure)
Totals
Weight
(kg)
3.5
81.65
37.7
-3.7
8.1
8.5
4.5
1.0
16.9
5.2
32.3
14.3
210.0
Price Factor
(per kg)
$10.45
-
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$3.00
$2.70
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$37
$1,324
$343
-$13
$58
$61
$33
$7
$51
$14
$323
$143
$2,380
$2,999
Calculation of fuel tank downsize (included above)
fuel efficiency improvement| 58.4% |
base mpg 14.63
base consumption (gpm) 0.0684
improved mpg 23.17
improved consumption (gpm) 0.0432
consumption reduction -36.9%
Initial
Final
full tank
delta
fuel tank size (gals)
fuel tank weight (kg)
28.0
10.0
17.7
6.3
(10.3)
(3.68)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-11: Incremental Costs
4WD SUV Gas, Variable Displacement, Mild Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
1 .4 gearset integrated into transfer case
Complexity Level #2 (like an Engine)
cost increase for variable displacement engine
1 10 cc pump motor (w/mounting flange for transfer case)
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
pump motor isolation mount (in addition to transfer case mount)
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
Battery upsize
7 gal composite accumulator (high pressure)
7 gal composite accumulator (low pressure)
Totals
Weight
(kg)
3.5
43.09
37.7
-2.3
8.1
8.5
4.5
1.0
16.9
5.2
32.3
14.3
172.8
Price Factor
(per kg)
$10.45
-
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$3.00
$2.70
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$37
$406
$343
-$17
$58
$61
$33
$7
$51
$14
$323
$143
$1,459
$1,838
Calculation of fuel tank downsize (included above)
fuel efficiency improvement] 30.8% |
base mpg 14.63
base consumption (gpm) 0.0684
improved mpg 19.14
improved consumption (gpm) 0.0523
consumption reduction -23.5%
Initial
Final
full tank
delta
fuel tank size (gals)
fuel tank weight (kg)
28.0
10.0
21.4
7.6
(6.6)
(2.35)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-12: Incremental Costs
4WD SUV Clean Diesel, Variable Displacement, Mild Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
1 .4 gearset integrated into transfer case
Complexity Level #2 (like an Engine)
cost increase for diesel engine
cost increase for variable displacement engine
1 10 cc pump motor (w/mounting flange for transfer case)
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
pump motor isolation mount (in addition to transfer case mount)
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
Battery upsize
7 gal composite accumulator (high pressure)
7 gal composite accumulator (low pressure)
Totals
Weight
(kg)
3.5
81.65
43.09
37.7
-4.4
8.1
8.5
4.5
1.0
16.9
5.2
32.3
14.3
252.4
Price Factor
(per kg)
$10.45
-
-
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$3.00
$2.70
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$37
$1,324
$406
$343
-$19
$58
$61
$33
$7
$51
$14
$323
$143
$2,781
$3,504
Calculation of fuel tank downsize (included above)
fuel efficiency improvement] 79.4% |
base mpg 14.63
base consumption (gpm) 0.0684
improved mpg 26.25
improved consumption (gpm) 0.0381
consumption reduction -44.3%
Initial
Final
full tank
delta
fuel tank size (gals)
fuel tank weight (kg)
28.0
10.0
15.6
5.6
(12.4)
(4.42)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-13: Incremental Cost
4WD SUV: Gas, Full Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
automatic transmission
transfer case
2 speed planetary (w/housing) for rear power unit
Complexity Level #2 (like an Engine)
engine downsize
power steering system (pump, reservior, steering gear)
135 cc engine pump motor (w/ mounting flange and bearing)
1 10 cc pump motor (combined frt power unit saves 8 kg est.)
1 1 0 cc motor for rear power unit
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
rear drive shaft
front drive shaft
transmission cooler and lines
fitting and hoses
accumulator mounting brackets
oil cooler and filter loop (front motor low side) + mount
engine/PM coupling and fasteners
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
15 gal composite accumulator (high pressure)
15 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-106.0
-47.3
15.0
-31.0
45.7
29.2
37.2
-1.4
-9.8
-7.3
-1.8
33.3
6.0
9.5
5.3
-11.8
38.8
56.0
23.4
83.0
Price Factor
($ per kg)
$10.45
$10.45
$10.45
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$1,108
-$494
$157
-$282
$0
$416
$266
$339
$0
$0
-$10
-$70
-$52
-$13
$239
$43
$68
$38
-$9
$116
$560
$234
$438
$552
Calculation of fuel tank downsize
fuel efficiency improvement
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
fuel tank size (gals)
fuel tank weight (kg)
(included above)
16.2%
14.63
0.0684
17.00
0.0588
-13.9%
Initial Final
28.0 24.1
10.0 8.6
full tank
delta
(3.9)
(1.39)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-14: Incremental Cost
4WD SUV Clean Diesel, Full Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
automatic transmission
transfer case
2 speed planetary (w/housing) for rear power unit
Complexity Level #2 (like an Engine)
engine downsize
cost increase for diesel engine
power steering system (pump, reservior, steering gear)
135 cc engine pump motor (w/ mounting flange and bearing)
1 10 cc pump motor (combined frt power unit saves 8 kg est.)
1 1 0 cc motor for rear power unit
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
rear drive shaft
front drive shaft
transmission cooler and lines
fitting and hoses
accumulator mounting brackets
oil cooler and filter loop (front motor low side) + mount
engine/PM coupling and fasteners
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
15 gal composite accumulator (high pressure)
15 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-106.0
-47.3
15.0
-31.0
81.6
45.7
29.2
37.2
-3.6
-9.8
-7.3
-1.8
33.3
6.0
9.5
5.3
-11.8
38.8
56.0
23.4
162.5
Price Factor
($ per kg)
$10.45
$10.45
$10.45
$9.11
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$1,108
-$494
$157
-$282
$1 ,324
$0
$416
$266
$339
$0
$0
-$13
-$70
-$52
-$13
$239
$43
$68
$38
-$9
$116
$560
$234
$1,759
$2,217
Calculation of fuel tank downsize (included above)
fuel efficiency improvement 56.5%
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
14.63
0.0684
22.90
0.0437
-36.1%
Initial
Final
full tank
delta
fuel tank size (gals) 28.0 17.9 (10.1)
fuel tank weight (kg) 10.0 6.4 (3.60)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-15: Incremental Cost
4WD SUV Gas, Variable Displacement, Full Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
automatic transmission
transfer case
2 speed planetary (w/housing) for rear power unit
Complexity Level #2 (like an Engine)
engine downsize
cost increase for variable displacement engine
power steering system (pump, reservior, steering gear)
135 cc engine pump motor (w/ mounting flange and bearing)
1 10 cc pump motor (combined frt power unit saves 8 kg est.)
1 1 0 cc motor for rear power unit
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
rear drive shaft
front drive shaft
transmission cooler and lines
fitting and hoses
accumulator mounting brackets
oil cooler and filter loop (front motor low side) + mount
engine/PM coupling and fasteners
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
15 gal composite accumulator (high pressure)
15 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-106.0
-47.3
15.0
-31.0
43.1
45.7
29.2
37.2
-2.3
-9.8
-7.3
-1.8
33.3
6.0
9.5
5.3
-11.8
38.8
56.0
23.4
125.2
Price Factor
($ per kg)
$10.45
$10.45
$10.45
$9.11
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$1,108
-$494
$157
-$282
$406
$0
$416
$266
$339
$0
$0
-$17
-$70
-$52
-$13
$239
$43
$68
$38
-$9
$116
$560
$234
$837
$1,055
Calculation of fuel tank downsize
fuel efficiency improvement
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
fuel tank size (gals)
fuel tank weight (kg)
(included above)
30.7%
14.63
0.0684
19.12
0.0523
-23.5%
Initial Final
28.0 21.4
10.0 7.6
full tank
delta
(6.6)
(2.34)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-16: Incremental Cost
4WD SUV Clean Diesel, Variable Displacement, Full Hydraulic Hybrid, Engine
On
Component
Complexity Level #1 (like a Transmission)
automatic transmission
transfer case
2 speed planetary (w/housing) for rear power unit
Complexity Level #2 (like an Engine)
engine downsize
cost increase for diesel engine
cost increase for variable displacement engine
power steering system (pump, reservior, steering gear)
135 cc engine pump motor (w/ mounting flange and bearing)
1 10 cc pump motor (combined frt power unit saves 8 kg est.)
1 1 0 cc motor for rear power unit
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
rear drive shaft
front drive shaft
transmission cooler and lines
fitting and hoses
accumulator mounting brackets
oil cooler and filter loop (front motor low side) + mount
engine/PM coupling and fasteners
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
15 gal composite accumulator (high pressure)
15 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-106.0
-47.3
15.0
-31.0
81.6
43.1
45.7
29.2
37.2
-4.4
-9.8
-7.3
-1.8
33.3
6.0
9.5
5.3
-11.8
38.8
56.0
23.4
204.8
Price Factor
($ per kg)
$10.45
$10.45
$10.45
$9.11
-
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$1,108
-$494
$157
-$282
$1 ,324
$406
$0
$416
$266
$339
$0
$0
-$19
-$70
-$52
-$13
$239
$43
$68
$38
-$9
$116
$560
$234
$2,160
$2,721
14.63
0.0684
26.13
0.0383
-44.0%
Initial
-
Calculation of fuel tank downsize (included above)
fuel efficiency improvement 78.6%
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
Final
full tank
delta
fuel tank size (gals) 28.0 15.7 (12.3)
fuel tank weight (kg) 10.0 5.6 (4.39)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-17: Incremental Cost
4WD SUV: Gas, Full Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
automatic transmission
transfer case
2 speed planetary (w/housing) for rear power unit
Complexity Level #2 (like an Engine)
engine downsize
power steering system (pump, reservior, steering gear)
135 cc engine pump motor (w/ mounting flange and bearing)
1 10 cc pump motor (combined frt power unit saves 8 kg est.)
1 1 0 cc motor for rear power unit
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
rear drive shaft
front drive shaft
transmission cooler and lines
fitting and hoses
accumulator mounting brackets
oil cooler and filter loop (front motor low side) + mount
engine/PM coupling and fasteners
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
15 gal composite accumulator (high pressure)
15 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-106.0
-47.3
15.0
-31.0
-17.3
45.7
29.2
37.2
15.6
4.5
-2.4
-9.8
-7.3
-1.8
33.3
6.0
9.5
5.3
-11.8
38.8
56.0
23.4
84.8
Price Factor
($ per kg)
$10.45
$10.45
$10.45
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$1,108
-$494
$157
-$282
-$158
$416
$266
$339
$142
$41
-$17
-$70
-$52
-$13
$239
$43
$68
$38
-$9
$116
$560
$234
$457
$575
Calculation of fuel tank downsize
fuel efficiency improvement
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
fuel tank size (gals)
fuel tank weight (kg)
(included above)
31.6%
14.63
0.0684
19.25
0.0519
-24.0%
Initial Final
28.0 21.3
10.0 7.6
full tank
delta
(6.7)
(2.40)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-18: Incremental Cost
4WD SUV Clean Diesel, Full Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
automatic transmission
transfer case
2 speed planetary (w/housing) for rear power unit
Complexity Level #2 (like an Engine)
engine downsize
cost increase for diesel engine
power steering system (pump, reservior, steering gear)
135 cc engine pump motor (w/ mounting flange and bearing)
1 10 cc pump motor (combined frt power unit saves 8 kg est.)
1 1 0 cc motor for rear power unit
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
rear drive shaft
front drive shaft
transmission cooler and lines
fitting and hoses
accumulator mounting brackets
oil cooler and filter loop (front motor low side) + mount
engine/PM coupling and fasteners
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
15 gal composite accumulator (high pressure)
15 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-106.0
-47.3
15.0
-31.0
81.6
-17.3
45.7
29.2
37.2
15.6
4.5
-4.5
-9.8
-7.3
-1.8
33.3
6.0
9.5
5.3
-11.8
38.8
56.0
23.4
164.4
Price Factor
($ per kg)
$10.45
$10.45
$10.45
$9.11
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$1,108
-$494
$157
-$282
$1 ,324
-$158
$416
$266
$339
$142
$41
-$19
-$70
-$52
-$13
$239
$43
$68
$38
-$9
$116
$560
$234
$1,778
$2,241
Calculation of fuel tank downsize (included above)
fuel efficiency improvement 82.3%
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
14.63
0.0684
26.67
0.0375
-45.1%
Initial
Final
full tank
delta
fuel tank size (gals) 28.0 15.4 (12.6)
fuel tank weight (kg) 10.0 5.5 (4.51)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-19: Incremental Cost
4WD SUV Gas, Variable Displacement, Full Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
automatic transmission
transfer case
2 speed planetary (w/housing) for rear power unit
Complexity Level #2 (like an Engine)
engine downsize
cost increase for variable displacement engine
power steering system (pump, reservior, steering gear)
135 cc engine pump motor (w/ mounting flange and bearing)
1 10 cc pump motor (combined frt power unit saves 8 kg est.)
1 1 0 cc motor for rear power unit
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
rear drive shaft
front drive shaft
transmission cooler and lines
fitting and hoses
accumulator mounting brackets
oil cooler and filter loop (front motor low side) + mount
engine/PM coupling and fasteners
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
15 gal composite accumulator (high pressure)
15 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-106.0
-47.3
15.0
-31.0
43.1
-17.3
45.7
29.2
37.2
15.6
4.5
-2.7
-9.8
-7.3
-1.8
33.3
6.0
9.5
5.3
-11.8
38.8
56.0
23.4
127.6
Price Factor
($ per kg)
$10.45
$10.45
$10.45
$9.11
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$1,108
-$494
$157
-$282
$406
-$158
$416
$266
$339
$142
$41
-$20
-$70
-$52
-$13
$239
$43
$68
$38
-$9
$116
$560
$234
$860
$1,084
Calculation of fuel tank downsize
fuel efficiency improvement
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
fuel tank size (gals)
fuel tank weight (kg)
(included above)
37.5%
14.63
0.0684
20.12
0.0497
-27.3%
Initial Final
28.0 20.4
10.0 7.3
full tank
delta
(7.6)
(2.72)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L1-20: Incremental Cost
4WD SUV Clean Diesel, Variable Displacement, Full Hydraulic Hybrid, Engine
Off
Component
Complexity Level #1 (like a Transmission)
automatic transmission
transfer case
2 speed planetary (w/housing) for rear power unit
Complexity Level #2 (like an Engine)
engine downsize
cost increase for diesel engine
cost increase for variable displacement engine
power steering system (pump, reservior, steering gear)
135 cc engine pump motor (w/ mounting flange and bearing)
1 10 cc pump motor (combined frt power unit saves 8 kg est.)
1 1 0 cc motor for rear power unit
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
rear drive shaft
front drive shaft
transmission cooler and lines
fitting and hoses
accumulator mounting brackets
oil cooler and filter loop (front motor low side) + mount
engine/PM coupling and fasteners
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
15 gal composite accumulator (high pressure)
15 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-106.0
-47.3
15.0
-31.0
81.6
43.1
-17.3
45.7
29.2
37.2
15.6
4.5
-4.9
-9.8
-7.3
-1.8
33.3
6.0
9.5
5.3
-11.8
38.8
56.0
23.4
207.0
Price Factor
($ per kg)
$10.45
$10.45
$10.45
$9.11
-
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$1,108
-$494
$157
-$282
$1 ,324
$406
-$158
$416
$266
$339
$142
$41
-$22
-$70
-$52
-$13
$239
$43
$68
$38
-$9
$116
$560
$234
$2,181
$2,749
Calculation of fuel tank downsize (included above)
fuel efficiency improvement 97.3%
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
14.63
0.0684
28.86
0.0346
-49.3%
Initial
Final
full tank
delta
fuel tank size (gals) 28.0 14.2 (13.8)
fuel tank weight (kg) 10.0 5.1 (4.92)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-1: Base Case Incremental Costs
Car: Gas, Conventional Transmission
Component
Totals
Weight
(kg)
0.0
Price Factor
($ per kg )
Supplier
Price
$0
Table L2-2: Incremental Costs
Car: Clean Diesel
Component
cost increase for diesel engine
net downsize of fuel tank
Totals
Weight
(kg)
42.2
42.2
Price Factor
($ per kg )
-
$7.19
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$957
$0
$957
$1,206
Calculation of fuel tank downsize (included above)
fuel efficiency improvement 37.5%
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 34.03
improved consumption (gpm) 0.0294
consumption reduction -27.3%
Initial
Final
full tank
delta
fuel tank size (gals) 28.0 20.4
fuel tank weight (kg) 10.0 7.3
(7.6)
(2.72)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-3: Incremental Costs
Car: Gas, Variable Displacement
Component
cost increase for variable displacement engine
net downsize of fuel tank
Totals
Weight
(kg)
28.9
-1.8
27.1
Price Factor
($ per kg )
-
$7.19
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$340
-$13
$327
$412
Calculation of fuel tank downsize (included above)
fuel efficiency improvement 21.7%
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
fuel tank size (gals)
fuel tank weight (kg)
24.75
0.0404
30.12
0.0332
-17.8%
Initial
28.0
10.0
Final
23.0
8.2
full tank
delta
(5.0)
(1.78)
Table L2-4: Incremental Costs
Car: Clean Diesel, Variable Displacement
Component
cost increase for diesel engine
cost increase for variable displacement engine
net downsize of fuel tank
Totals
Weight
(kg)
42.2
28.9
-3.8
67.3
Price Factor
($ per kg )
$7.19
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$957
$340
-$17
$1,280
$1,612
Calculation of fuel tank downsize (included above)
fuel efficiency improvement 62.0%
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 40.10
improved consumption (gpm) 0.0249
consumption reduction -38.3%
Initial
Final
full tank
delta
fuel tank size (gals) 28.0 17.3
fuel tank weight (kg) 10.0 6.2
(10.7)
(3.82)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-5: Incremental Costs
Car: Gas, Mild Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
additional input to final drive of trans, extra housing, mounts, chain
Complexity Level #2 (like an Engine)
55 cc pump motor
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
4 gal composite accumulator (high pressure)
4 gal composite accumulator (low pressure)
Totals
Weight
(kg)
8.3
18.6
-1.3
13.8
5.0
4.0
9.6
24.0
11.2
93.2
Price Factor
($ per kg)
$10.45
$9.11
$7.19
$7.19
$7.19
$7.19
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$87
$169
-$9
$99
$36
$29
$29
$240
$112
$792
$998
Calculation of fuel tank downsize (included above)
fuel efficiency improvement] 11.2% |
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 27.52
improved consumption (gpm) 0.0363
consumption reduction
fuel tank size (gals)
fuel tank weight (kg)
-10.1%
Initial
16.0
12.7
Final
14.4
11.4
full tank
delta
(1.6)
(1.28)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-6: Incremental Costs
Car: Clean Diesel, Mild Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
additional input to final drive of trans, extra housing, mounts, chain
Complexity Level #2 (like an Engine)
cost increase for diesel engine
55 cc pump motor
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
4 gal composite accumulator (high pressure)
4 gal composite accumulator (low pressure)
Totals
Weight
(kg)
8.3
42.2
18.6
-5.0
13.8
5.0
4.0
9.6
24.0
11.2
131.7
Price Factor
($ per kg)
$10.45
-
$9.11
$7.19
$7.19
$7.19
$7.19
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$87
$957
$169
-$26
$99
$36
$29
$29
$240
$112
$1,732
$2,182
Calculation of fuel tank downsize (included above)
fuel efficiency improvement] 65.4% |
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 40.94
improved consumption (gpm) 0.0244
consumption reduction -39.5%
fuel tank size (gals)
fuel tank weight (kg)
Initial
16.0
12.7
Final
9.7
7.7
full tank
delta
(6.3)
(5.02)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-7: Incremental Costs
Car: Gas, Variable Displacement, Mild Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
additional input to final drive of trans, extra housing, mounts, chain
Complexity Level #2 (like an Engine)
cost increase for variable displacement engine
55 cc pump motor
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
4 gal composite accumulator (high pressure)
4 gal composite accumulator (low pressure)
Totals
Weight
(kg)
8.3
28.9
18.6
-3.5
13.8
5.0
4.0
9.6
24.0
11.2
119.9
Price Factor
($ per kg)
$10.45
-
$9.11
$7.19
$7.19
$7.19
$7.19
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$87
$314
$169
-$25
$99
$36
$29
$29
$240
$112
$1,089
$1,373
Calculation of fuel tank downsize (included above)
fuel efficiency improvement] 38.7% |
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 34.33
improved consumption (gpm) 0.0291
consumption reduction -27.9%
Initial
Final
full tank
delta
fuel tank size (gals) 16.0 11.5
fuel tank weight (kg) 12.7 9.2
(4.5)
(3.54)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-8: Incremental Costs
Car: Clean Diesel, Variable Displacement, Mild Hydraulic Hybrid, Engine
On
Component
Complexity Level #1 (like a Transmission)
additional input to final drive of trans, extra housing, mounts, chain
Complexity Level #2 (like an Engine)
cost increase for diesel engine
cost increase for variable displacement engine
55 cc pump motor
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
4 gal composite accumulator (high pressure)
4 gal composite accumulator (low pressure)
Totals
Weight
(kg)
8.3
42.2
28.9
18.6
-6.2
13.8
5.0
4.0
9.6
24.0
11.2
159.4
Price Factor
($ per kg)
$10.45
-
-
$9.11
$7.19
$7.19
$7.19
$7.19
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$87
$957
$314
$169
-$35
$99
$36
$29
$29
$240
$112
$2,037
$2,567
Calculation of fuel tank downsize (included above)
95.8% I
fuel efficiency improvement]
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 48.46
improved consumption (gpm) 0.0206
consumption reduction
fuel tank size (gals)
fuel tank weight (kg)
-48.9%
Initial
16.0
12.7
Final
8.2
6.5
full tank
delta
(7.8)
(6.21)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-9: Incremental Costs
Car: Gas, Mild Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
additional input to final drive of trans, extra housing, mounts, chain
Complexity Level #2 (like an Engine)
55 cc pump motor
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
battery upsize
4 gal composite accumulator (high pressure)
4 gal composite accumulator (low pressure)
Totals
Weight
(kg)
8.3
18.6
-1.8
13.8
5.0
4.0
9.6
4.6
24.0
11.2
97.3
Price Factor
($ per kg)
$10.45
$9.11
$7.19
$7.19
$7.19
$7.19
$3.00
$2.70
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$87
$169
-$13
$99
$36
$29
$29
$12
$240
$112
$800
$1,009
Calculation of fuel tank downsize (included above)
fuel efficiency improvement] 16.4% |
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 28.81
improved consumption (gpm) 0.0347
consumption reduction -14.1%
Initial
Final
full tank
delta
fuel tank size (gals) 16.0 13.7
fuel tank weight (kg) 12.7 10.9
(2.3)
(1.79)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-10: -Incremental Costs
Car: Clean Diesel, Mild Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
additional input to final drive of trans, extra housing, mounts, chain
Complexity Level #2 (like an Engine)
cost increase for diesel engine
55 cc pump motor
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
battery upsize
4 gal composite accumulator (high pressure)
4 gal composite accumulator (low pressure)
Totals
Weight
(kg)
8.3
42.2
18.6
-5.3
13.8
5.0
4.0
9.6
4.6
24.0
11.2
136.0
Price Factor
($ per kg)
$10.45
$9.11
$7.19
$7.19
$7.19
$7.19
$3.00
$2.70
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$87
$957
$169
-$28
$99
$36
$29
$29
$12
$240
$112
$1,742
$2,195
Calculation of fuel tank downsize (included above)
70.9% I
fuel efficiency improvement]
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 42.30
improved consumption (gpm) 0.0236
consumption reduction
fuel tank size (gals)
fuel tank weight (kg)
-41.5%
Initial
16.0
12.7
Final
9.4
7.4
full tank
delta
(6.6)
(5.27)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-11: -Incremental Costs
Car: Gas, Variable Displacement, Mild Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
additional input to final drive of trans, extra housing, mounts, chain
Complexity Level #2 (like an Engine)
cost increase for variable displacement engine
55 cc pump motor
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
battery upsize
4 gal composite accumulator (high pressure)
4 gal composite accumulator (low pressure)
Totals
Weight
(kg)
8.3
28.9
18.6
-3.8
13.8
5.0
4.0
9.6
4.6
24.0
11.2
124.2
Price Factor
($ per kg)
$10.45
$9.11
$7.19
$7.19
$7.19
$7.19
$3.00
$2.70
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$87
$314
$169
-$27
$99
$36
$29
$29
$12
$240
$112
$1,100
$1,386
Calculation of fuel tank downsize (included above)
fuel efficiency improvement] 42.7% |
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 35.32
improved consumption (gpm) 0.0283
consumption reduction -29.9%
Initial
Final
full tank
delta
fuel tank size (gals) 16.0
fuel tank weight (kg) 12.7
11.2
8.9
(4.8)
(3.80)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-12: -Incremental Costs
Car: Clean Diesel, Variable Displacement, Mild Hydraulic Hybrid, Engine
Off
Component
Complexity Level #1 (like a Transmission)
additional input to final drive of trans, extra housing, mounts, chain
Complexity Level #2 (like an Engine)
cost increase for diesel engine
cost increase for variable displacement engine
55 cc pump motor
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
fluid in HP accumulator, fittings, hoses, oil conditioner
battery upsize
4 gal composite accumulator (high pressure)
4 gal composite accumulator (low pressure)
Totals
Weight
(kg)
8.3
42.2
28.9
18.6
-6.4
13.8
5.0
4.0
9.6
4.6
24.0
11.2
163.8
Price Factor
($ per kg)
$10.45
$9.11
$7.19
$7.19
$7.19
$7.19
$3.00
$2.70
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
$87
$957
$314
$169
-$36
$99
$36
$29
$29
$12
$240
$112
$2,048
$2,581
Calculation of fuel tank downsize (included above)
fuel efficiency improvement] 101.6% |
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 49.90
improved consumption (gpm) 0.0200
consumption reduction -50.4%
fuel tank size (gals)
fuel tank weight (kg)
Initial
16.0
12.7
Final
7.9
6.3
full tank
delta
(8.1)
(6.40)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-13: Incremental Costs
Car: Gas, Full Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
automatic transmission
integrated transmission (w/o motors)
Complexity Level #2 (like an Engine)
engine downsize
power steering system (pump, reservior, steering gear)
65 cc drive motor
80 cc drive motor
80 cc pump motor
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
10 gal composite accumulator (high pressure)
10 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-85.0
41.3
-21.0
22.0
27.1
27.1
-2.4
14.4
6.5
6.0
-10.0
24.1
41.7
18.1
109.8
Price Factor
($ per kg )
$10.45
$10.45
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$888
$432
-$191
$0
$200
$246
$246
$0
$0
-$17
$104
$47
$43
-$8
$72
$417
$181
$884
$1,114
Calculation of fuel tank downsize (included a bo ve)
fuel efficiency improvement | 23.2% |
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
24.75
0.0404
30.49
0.0328
-18.8%
Initial
Final
fuel tank size (gals) 16.0 13.0
fuel tank weight (kg) 12.7 10.3
full tank
delta
(3.0)
(2.39)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-14: Incremental Costs
Car: Clean Diesel, Full Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
automatic transmission
integrated transmission (w/o motors)
Complexity Level #2 (like an Engine)
engine downsize
cost increase for diesel engine
power steering system (pump, reservior, steering gear)
65 cc drive motor
80 cc drive motor
80 cc pump motor
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
10 gal composite accumulator (high pressure)
10 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-85.0
41.3
-21.0
42.2
22.0
27.1
27.1
-5.2
14.4
6.5
6.0
-10.0
24.1
41.7
18.1
149.1
Price Factor
($ per kg )
$10.45
$10.45
$9.11
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$888
$432
-$191
$957
$0
$200
$246
$246
$0
$0
-$28
$104
$47
$43
-$8
$72
$417
$181
$1,831
$2,307
Calculation of fuel tank downsize (included a bo ve)
fuel efficiency improvement | 70.4%
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 42.17
improved consumption (gpm) 0.0237
consumption reduction -41.3%
Initial
fuel tank size (gals) 1 6.0
fuel tank weight (kg) 12.7
full tank
Final delta
9.4 (6.6)
7.5 (5.25)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Car:
Table L2-15: Incremental Costs
Gas, Variable Displacement, Full Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
automatic transmission
integrated transmission (w/o motors)
Complexity Level #2 (like an Engine)
engine downsize
cost increase for variable displacement engine
power steering system (pump, reservior, steering gear)
65 cc drive motor
80 cc drive motor
80 cc pump motor
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
10 gal composite accumulator (high pressure)
10 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-85.0
41.3
-21.0
28.9
22.0
27.1
27.1
-4.2
14.4
6.5
6.0
-10.0
24.1
41.7
18.1
136.8
Price Factor
($ per kg )
$10.45
$10.45
$9.11
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$888
$432
-$191
$314
$0
$200
$246
$246
$0
$0
-$30
$104
$47
$43
-$8
$72
$417
$181
$1,185
$1,493
Calculation of fuel tank downsize (included a bo ve)
fuel efficiency improvement | 50.1%
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 37.15
improved consumption (gpm) 0.0269
consumption reduction -33.4%
Initial
fuel tank size (gals) 1 6.0
fuel tank weight (kg) 12.7
full tank
Final delta
10.7 (5.3)
8.5 (4.24)
Progress Report on Clean and Efficient Automotive Technologies
-------
Car:
Table L2-16: Incremental Costs
Clean Diesel, Variable Displacement, Full Hydraulic Hybrid, Engine On
Component
Complexity Level #1 (like a Transmission)
automatic transmission
integrated transmission (w/o motors)
Complexity Level #2 (like an Engine)
engine downsize
cost increase for diesel engine
cost increase for variable displacement engine
power steering system (pump, reservior, steering gear)
65 cc drive motor
80 cc drive motor
80 cc pump motor
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
10 gal composite accumulator (high pressure)
10 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-85.0
41.3
-21.0
42.2
28.9
22.0
27.1
27.1
-6.3
14.4
6.5
6.0
-10.0
24.1
41.7
18.1
176.9
Price Factor
($ per kg )
$10.45
$10.45
$9.11
-
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$888
$432
-$191
$957
$314
$0
$200
$246
$246
$0
$0
-$36
$104
$47
$43
-$8
$72
$417
$181
$2,137
$2,692
Calculation of fuel tank downsize (included a bo ve)
fuel efficiency improvement | 99.6%
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 49.40
improved consumption (gpm) 0.0202
consumption reduction -49.9%
Initial
fuel tank size (gals) 1 6.0
fuel tank weight (kg) 12.7
full tank
Final delta
8.0 (8.0)
6.4 (6.34)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-17: Incremental Costs
Car: Gas, Full Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
automatic transmission
integrated transmission (w/o motors)
Complexity Level #2 (like an Engine)
engine downsize
power steering system (pump, reservior, steering gear)
65 cc drive motor
80 cc drive motor
80 cc pump motor
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
10 gal composite accumulator (high pressure)
10 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-85.0
41.3
-21.0
-12.3
22.0
27.1
27.1
11.8
3.5
-4.1
14.4
6.5
6.0
-10.0
24.1
41.7
18.1
111.1
Price Factor
($ per kg )
$10.45
$10.45
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$888
$432
-$191
-$112
$200
$246
$246
$107
$32
-$29
$104
$47
$43
-$8
$72
$417
$181
$899
$1,133
Calculation of fuel tank downsize (included a bo ve)
fuel efficiency improvement | 47.4% |
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
24.75
0.0404
36.48
0.0274
-32.2%
Initial
Final
fuel tank size (gals) 16.0 10.9
fuel tank weight (kg) 12.7 8.6
full tank
delta
(5.1)
(4.08)
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-18: Incremental Costs
Car: Clean Diesel, Full Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
automatic transmission
integrated transmission (w/o motors)
Complexity Level #2 (like an Engine)
engine downsize
cost increase for diesel engine
power steering system (pump, reservior, steering gear)
65 cc drive motor
80 cc drive motor
80 cc pump motor
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
10 gal composite accumulator (high pressure)
10 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-85.0
41.3
-21.0
42.2
-12.3
22.0
27.1
27.1
11.8
3.5
-6.4
14.4
6.5
6.0
-10.0
24.1
41.7
18.1
150.9
Price Factor
($ per kg )
$10.45
$10.45
$9.11
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$888
$432
-$191
$957
-$112
$200
$246
$246
$107
$32
-$36
$104
$47
$43
-$8
$72
$417
$181
$1,849
$2,330
Calculation of fuel tank downsize (included a bo ve)
fuel efficiency improvement | 103.0%
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 50.24
improved consumption (gpm) 0.0199
consumption reduction -50.7%
Initial
fuel tank size (gals) 16.0
fuel tank weight (kg) 12.7
full tank
Final delta
I 7.9 (8.1)
6.3 (6.44)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
Table L2-19: Incremental Costs
Car: Gas, Variable Displacement, Full Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
automatic transmission
integrated transmission (w/o motors)
Complexity Level #2 (like an Engine)
engine downsize
cost increase for variable displacement engine
power steering system (pump, reservior, steering gear)
65 cc drive motor
80 cc drive motor
80 cc pump motor
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
10 gal composite accumulator (high pressure)
10 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-85.0
41.3
-21.0
28.9
-12.3
22.0
27.1
27.1
11.8
3.5
-4.5
14.4
6.5
6.0
-10.0
24.1
41.7
18.1
139.6
Price Factor
($ per kg )
$10.45
$10.45
$9.11
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$888
$432
-$191
$314
-$112
$200
$246
$246
$107
$32
-$32
$104
$47
$43
-$8
$72
$417
$181
$1,211
$1,525
Calculation of fuel tank downsize (included a bo ve)
fuel efficiency improvement | 54.1%
base mpg 24.75
base consumption (gpm) 0.0404
improved mpg 38.14
improved consumption (gpm) 0.0262
consumption reduction -35.1%
Initial
fuel tank size (gals) 1 6.0
fuel tank weight (kg) 12.7
full tank
Final delta
10.4 (5.6)
8.2 (4.46)
Progress Report on Clean and Efficient Automotive Technologies
-------
Car:
Table L2-20: Incremental Costs
Clean Diesel, Variable Displacement, Full Hydraulic Hybrid, Engine Off
Component
Complexity Level #1 (like a Transmission)
automatic transmission
integrated transmission (w/o motors)
Complexity Level #2 (like an Engine)
engine downsize
cost increase for diesel engine
cost increase for variable displacement engine
power steering system (pump, reservior, steering gear)
65 cc drive motor
80 cc drive motor
80 cc pump motor
on-demand power steering system
hydraulic driven alternator
Complexity Level #3 (like a Chassis)
net downsize of fuel tank
fitting and hoses
oil cooler and filter loop (front motor low side)
accumulator mounting brackets
Other Complexity Levels
transmission fluid
fluid in HP accumulator, fittings, hoses, oil conditioner
10 gal composite accumulator (high pressure)
10 gal composite accumulator (low pressure)
Totals
Weight
(kg)
-85.0
41.3
-21.0
42.2
28.9
-12.3
22.0
27.1
27.1
11.8
3.5
-6.9
14.4
6.5
6.0
-10.0
24.1
41.7
18.1
179.4
Price Factor
($ per kg )
$10.45
$10.45
$9.11
-
-
$9.11
$9.11
$9.11
$9.11
$9.11
$9.11
$7.19
$7.19
$7.19
$7.19
$0.75
$3.00
$10.00
$10.00
Increment in Vehicle Consumer Retail Price (Supplier Price x RPE of 1.26)
Supplier
Price
-$888
$432
-$191
$957
$314
-$112
$200
$246
$246
$107
$32
-$39
$104
$47
$43
-$8
$72
$417
$181
$2,160
$2,722
Calculation of fuel tank downsize (included a bo ve)
fuel efficiency improvement | 117.9% |
base mpg
base consumption (gpm)
improved mpg
improved consumption (gpm)
consumption reduction
24.75
0.0404
53.93
0.0185
-54.1%
Initial
Final
fuel tank size (gals) 16.0
fuel tank weight (kg) 12.7
7.3
5.8
full tank
delta
(8.7)
(6.87)
*An adjustment was made to this value to account for the partial credit already
taken for fuel tank downsize in the above cost of changing to a diesel engine.
Progress Report on Clean and Efficient Automotive Technologies
-------
APPENDIX M
Appendix M: Methodology for Brake Savings
A conventional vehicle accomplishes disc braking by converting the kinetic energy of the vehicle
to heat through friction between the brake pad and the rotor. This friction between the brake
pad and the rotor wears both surfaces and these parts will eventually need to be replaced.
During a typical braking event on the hydraulic hybrid vehicle more than 90 percent of the
energy that is dissipated as heat in a conventional vehicle will be recovered and stored in the
accumulator. Although a hydraulic hybrid vehicle will also require a friction braking system, the
reduction in the energy that must be absorbed by the friction braking system greatly reduces the
wear on the brake pads and rotors. This analysis assumes the overall brake wear on a hydraulic
hybrid vehicle will be reduced by 70% in comparison to a conventional vehicle.
This analysis also assumes that the friction braking system on a hydraulic hybrid vehicle would
be exactly the same as the friction braking system on a similar conventional vehicle. The friction
braking system was not downsized to guarantee that hydraulic hybrid vehicle will be capable of
at least the same braking performance as a conventional vehicle in all situations.
The maintenance schedules for a number of conventional passenger cars and sport/utility
vehicles call for the brake system to be inspected at regular intervals. However, no part of the
brake system appears to have a mileage limit or a suggested replacement interval. That is, in part,
because brake wear is a function of both driving conditions and driving style. For example, if one
drives for long periods of time in stop-and-go traffic, drives in the mountains or carries heavy
loads, the brake system will likely need maintenance sooner than if most of one's driving is on
the highway.
At a May 15, 2001 Brake Symposium sponsored by Pro-Cut International, Daimler-Chrysler
engineers stated that the target front brake life for Jeep products was at least 25,000 miles for a
heavily loaded vehicle in the city driving test.
An internet article entitled "Tech Forum: Brakes"3 states that "Many times, a set of front disc
brake pads may be all that is needed when a vehicle has its first brake job. If a brake system only
has 30,000 to 40,000 miles on it, chances are the rest of the system is still in relatively good
condition and needs little attention. ... By the time a vehicle is ready for its second or third brake
job, the situation is usually entirely different. By this time the vehicle has 60,000 to 80,000 or
more miles on it, numerous brake components may need to be replaced."
For the purposes of this analysis it has been assumed that a conventional vehicle under typical
driving conditions will need brake maintenance at 40,000 mile intervals according to the
following schedule. This maintenance schedule also assumes that the front brakes bear twice the
burden of slowing the vehicle as do the rear brakes.
http://www.babcox.com/editorial/cm/cm80226.htm
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page M-l
-------
APPENDIX M
Maintenance Schedule
Mileage
40,000
80,000
120,000
160,000
Front Brakes
Replace pads, machine rotors
Replace pads and rotors
Replace pads, machine rotors
Replace pads and rotors
Rear Brakes
Replace pads, machine rotors
Replace pads and rotors
The cost of brake maintenance is a function of parts cost, labor hours required to perform the
maintenance and the hourly shop rate.
Ford Parts Cost4
Part
Front Brake Pad
Front Rotor
Rear Brake Pad
Rear Rotor
2000 Taurus
$59.70
$99.98
$67.57
$88.20
2000 Expedition 4WD
$95.16
$91.33
$81.12
$124.13
Parts costs vary. OEM parts tend to cost more. Aftermarket parts tend to cost less than OEM
parts, sometimes a lot less.
Aftermarket Parts Cost
Part
Front Brake Pad5
Front Rotor6
Rear Brake Pad3
Rear Rotor4
2000 Taurus
$30.99
$31.99
$31.99
$21.49
2000 Expedition 4WD
$50.99
$34.99
$49.99
$58.99
The number of labor hours charged to complete a job also depends upon the work to be done as
well as the type of facility doing the work.
http ://fordpartsnetwork. com
http://www.autozone.com
6 http://www.napaonline.com
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies page M-2
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APPENDIX M
Dealership Flat Rate Labor Hours
Maintenance
Replace front pads, machine rotors
Replace front pads and rotors
Replace rear pads, machine rotors
Replace rear pads and rotors
Passenger Vehicle
2.0
1.6
2.8
2.4
Sport/Utility Vehicle
2.0
1.6
2.8
2.4
Dealerships tend to charge more for these services because they have more overhead, their
mechanics generally have more certifications so they have to pay them more and they have more
sophisticated diagnostic equipment than independent repair establishments. This analysis
assumes that dealerships allocate about 10% more labor for brake maintenance than do either
independent repair facilities or franchises.7
Independent Repair Shop Flat Rate Labor Hours8
Maintenance
Replace front pads, machine rotors
Replace front pads and rotors
Replace rear pads, machine rotors
Replace rear pads and rotors
Passenger Vehicle
1.8
1.4
2.5
2.2
Sport/Utility Vehicle
1.8
1.4
2.5
2.2
Franchise Flat Rate Labor Hours
Maintenance
Replace front pads, machine rotors
Replace front pads and rotors
Replace rear pads, machine rotors
Replace rear pads and rotors
Passenger Vehicle
1.8
1.4
2.5
2.2
Sport/Utility Vehicle
1.8
1.4
2.5
2.2
Shop rates vary by region of the country as well as whether the repair facility is a franchise,
independent or part of a dealership. Dealership shop rates tend to be higher. This analysis uses
two shop rates: $49.809 for franchises and independent repair facilities and $75.00 for
dealerships.
To summarize, this analysis postulates three types of repair facilities with the work divided
among them: franchises (40%), independent repair shops (40%) and dealerships (20%).
Franchises and independent repair facilities are assumed to use the less expensive parts;
Based on personal communication between Varsity Ford, Ann Arbor, MI 41830 and Julie Schaefer.
ALLDATA DIY: Individual Online Diagnostic and Repair Information for the Automotive Enthusiast.
http://www.alldata.com/
Brake & Front End 2001 Service and Repair Survey, Babcox Research, Akron, Ohio
http://www.aftermarketnews.com/01brkservice.pdf
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies page M-3
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APPENDIX M
dealerships are assumed to use OEM parts. Franchises and independent repair facilities are
assumed to charge the same shop rate; dealerships are assumed to charge a higher shop rate.
Franchises and independent repair facilities are assumed to estimate the time it takes to perform a
job that is about 10% lower than that listed in the flat rate manual; dealerships are assumed to
estimate the time it takes to perform a job that is equal to the flat rate manual.
This analysis also assumes that cars accumulate 153,000 miles during the first 14 years, that
sport/utility vehicles accumulate 188,000 miles, and that future costs are discounted at the rate of
7% per year10. Seven percent is the discount rate used in EPA's regulatory analyses and is based
on OMB guidance.
Mileage Accumulation Rates11
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
MOBILE6
LDVVMT
14,910
14,174
13,475
12,810
12,178
11,577
11,006
10,463
9,947
9,456
8,989
8,546
8,124
7,723
MOBILE6
LDT VMT
19,978
18,695
17,494
16,371
15,319
14,335
13,414
12,553
11,746
10,992
10,286
9,625
9,007
8,428
Cumulative
MOBILE6
LDVVMT
14,910
29,084
42,559
55,369
67,547
79,125
90,130
100,593
110,540
119,996
128,985
137,531
145,655
153,378
Cumulative
MOBILE6
LDT VMT
19,978
38,674
56,168
72,538
87,857
102,192
115,607
128,159
139,905
150,897
161,183
170,808
179,814
188,242
Discount Factors
Age
Cumulative
MOBILE6
Cumulative
MOBILE6
Discount
Factor
10
OMB Circular A-94 Revised http://www.whitehouse.gov/omb/circulars/a094/a094.html Special
Guidance for Regulatory Impact Analysis. Additional guidance for analysis of regulatory policies is provided
in Regulatory Program of the United States Government which is published annually by OMB. (See
"Regulatory Impact Analysis Guidance," Appendix V of Regulatory Program of the United States Government
for April 1, 1991 to March 31, 1992.)
U.S. Environmental Protection Agency, MOBILE6 Emissions model
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies page M-4
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APPENDIX M
(years)
2.08
2.81
4.49
6.08
7.35
10.00
10.89
8.44
11.47
LDV VMT LDT VMT
40,000
40,000
80,000
80,000
120,000
120,000
160,000
133,333
133,333
7%
0.93
0.88
0.79
0.71
0.65
0.54
0.51
0.60
0.49
Dealership Discounted Cost
Mileage
40,000
80,000
120,000
160,000
Total
2000 Taurus
$185.52
$466.06
$114.05
$765.62
2000 Expedition 4WD
$227.94
$544.12
$159.53
$464.76
$1,396.35
Independent Repair Facility Discounted Cost
Mileage
40,000
80,000
120,000
160,000
Total
2000 Taurus
$106.73
$229.89
$65.61
$402.22
2000 Expedition 4WD
$130.76
$290.79
$91.51
$239.88
$752.94
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies page M-5
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APPENDIX M
Franchise Discounted Cost
Mileage
40,000
80,000
120,000
160,000
Total
2000 Taurus
$106.73
$229.89
$65.61
$402.22
2000 Expedition 4WD
$130.76
$290.79
$91.51
$239.88
$752.94
Weighted Average Discounted Cost
Mileage
40,000
80,000
120,000
160,000
Total
2000 Taurus
$122.48
$277.12
$75.30
$474.90
2000 Expedition 4WD
$150.19
$341.46
$105.12
$284.85
$881.62
Several brake repair facilities in the Ann Arbor, Michigan area were called on October 12, 2002
to obtain estimates on the cost of replacing the front brake pads and resurfacing the front brake
rotors.12 A summary of these telephone calls follows:
Local Franchise Cost
Facility
Midas
Tuffy
Speedy
Mr. Muffler
1999 Taurus
$99.99
$110.00 -$120.00
$140.00
1999 Expedition
$99.99
$110.00
These costs correspond to the 40,000 mile estimated franchise cost - before applying the 7%
OMB discount - of replacing the front brake pads and machining the front rotors of $120.63 for
cars and $140.63 for light trucks.
We project that hydraulic hybrid vehicles will reduce brake wear by 70%. That means that the
first and only brake maintenance expense would occur at 133,333 miles.
Weighted Average Discounted Cost
Mileage
133,000
2000 Taurus
$67.99
2000 Expedition 4WD
$97.64
Based on personal communication between listed local repair facilities and Tony Tesoriero. October 12, 2002
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies page M-6
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APPENDIX M
Even if brake wear were reduced by only 50% for hybrid cars and 60% for hybrid light trucks,
only one brake maintenance expense would be expected in the first 14 years of a vehicle's life.
Discounted Net Savings
2000 Taurus
$407
2000 Expedition 4WD
$784
Conclusion
Hybrid vehicles are expected to require significantly less brake maintenance over the first 14
years of their life, saving, in today's dollars, more than $400 for cars and almost $800 for light
trucks.13
The savings for any particular calendar year depend upon the fraction of the fleet that needs brake maintenance
in that year and the discounted cost of those repairs.
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies page M-7
-------
APPENDIX N
Appendix N: Calculations of Payback by Technology
Appendix N provides the detailed payback data for each of 80 technology scenarios, 40 base
roadload scenarios presented in the body of the report and 40 reduced roadload scenarios
presented in Appendix A. For this Appendix, the 80 scenarios are arranged in groups defined by
vehicle type (midsize car or large SUV), drivetrain (conventional or hydraulic), and roadload
(base or reduced). Each of the tables in the Appendix provides the amount of discounted savings
due to improved fuel economy and reduced brake maintenance. These savings are presented by
vehicle age (the first column of each set of tables) and are compared to the incremental cost of
the technology. The final column in each technology table gives the age at which the breakeven
point or payback occurs.
Tables Nl-1 through Nl-10 contain cost data for SUV configurations.
Tables N2-1 through N2-10 contain cost data for Car configurations.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page N-l
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Appendix N
Calculations of Payback by Technology
Table N1-1 : Large 4WD SUV Conventional Transmission
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
Base Base Base
Clean Diesel Engine
$/Age Cum$ PaybkAge
$552 $552
$483 $1,035
$422 $1,457
$369 $1,826 3.6
$323 $2,149
$283 $2,432
$247 $2,679
$216 $2,895
$189 $3,084
$165 $3,249
$145 $3,394
$126 $3,520
$111 $3,631
$97 $3,728
$3,728
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$253 $253
$221 $474
$193 $667 2.3
$169 $836
$148 $984
$129 $1,113
$113 $1,226
$99 $1,325
$87 $1,412
$76 $1,488
$66 $1,554
$58 $1,612
$51 $1,663
$44 $1,707
$1,707
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$731 $731
$639 $1,370
$559 $1,929
$489 $2,418 3.5
$427 $2,845
$374 $3,219
$327 $3,546
$286 $3,832
$250 $4,082
$219 $4,301
$191 $4,492
$167 $4,659
$146 $4,805
$128 $4,933
$4,933
Table N1-2: Large 4WD SUV Conventional Transmission
Reduced Roadload
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$162 $162
$142 $304 1.3
$124 $428
$109 $537
$95 $632
$83 $715
$73 $788
$64 $852
$56 $908
$49 $957
$43 $1,000
$37 $1,037
$33 $1,070
$28 $1,098
$1,098
Clean Diesel Engine
$/Age Cum$ PaybkAge
$682 $682
$596 $1,278
$521 $1,799
$456 $2,255 3.2
$399 $2,654
$349 $3,003
$305 $3,308
$267 $3,575
$233 $3,808
$204 $4,012
$178 $4,190
$156 $4,346
$136 $4,482
$119 $4,601
$4,601
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$446 $446
$390 $836 1.8
$341 $1,177
$298 $1,475
$261 $1,736
$228 $1,964
$199 $2,163
$174 $2,337
$153 $2,490
$133 $2,623
$117 $2,740
$102 $2,842
$89 $2,931
$78 $3,009
$3,009
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$865 $865
$756 $1,621
$661 $2,282
$578 $2,860 3.2
$506 $3,366
$442 $3,808
$387 $4,195
$338 $4,533
$296 $4,829
$259 $5,088
$226 $5,314
$198 $5,512
$173 $5,685
$151 $5,836
$5,836
N-2
-------
Appendix N
Calculations of Payback by Technology
Table N1-3: Large 4WD SUV Mild Hydraulic Hybrid - Engine On |
Age
1
2
2.08
3
4
4.49
5
6
7
7.35
8
8.44
9
10
10.89
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
iv Gas Engine Clea
$/Age Cum$ PaybkAge
$221 $221
$193 $414
$150 $564
$169 $733
$148 $881
$341 $1,222
$129 $1,351 4.9
$113 $1,464
$99 $1,563
$105 $1,668
$87 $1,755
-$98 $1,657
$76 $1,733
$66 $1,799
$285 $2,084
$58 $2,142
$51 $2,193
$44 $2,237
$39 $2,276
$2,276
n Diesel Engine Gas
$/Age Cum$ PaybkAge
$731 $731
$639 $1,370
$150 $1,520
$559 $2,079
$489 $2,568
$341 $2,909
$427 $3,336 4.6
$374 $3,710
$327 $4,037
$105 $4,142
$286 $4,428
-$98 $4,330
$250 $4,580
$219 $4,799
$285 $5,084
$191 $5,275
$167 $5,442
$146 $5,588
$128 $5,716
$5,716
Var Disp Engine Clean Di
$/Age Cum$ PaybkAge
$460 $460
$403 $863
$150 $1,013
$352 $1,365
$308 $1,673
$341 $2,014 4.2
$269 $2,283
$235 $2,518
$206 $2,724
$105 $2,829
$180 $3,009
-$98 $2,911
$157 $3,068
$138 $3,206
$285 $3,491
$120 $3,611
$105 $3,716
$92 $3,808
$81 $3,889
$3,889
3sel Var Disp Engine
$/Age Cum$ PaybkAge
$892 $892
$780 $1,672
$150 $1,822
$682 $2,504
$597 $3,101
$341 $3,442
$522 $3,964 4.5
$456 $4,420
$399 $4,819
$105 $4,924
$349 $5,273
-$98 $5,175
$305 $5,480
$267 $5,747
$285 $6,032
$234 $6,266
$204 $6,470
$179 $6,649
$156 $6,805
$6,805
Table N1-4: Large 4WD SUV Mild Hydraulic Hybrid - Engine On
Reduced Roadload
Age
1
2
2.08
3
4
4.49
5
6
7
7.35
8
8.44
9
10
10.89
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
iv Gas Engine Clea
$/Age Cum$ PaybkAge
$399 $399
$349 $748
$150 $898
$305 $1,203
$267 $1,470
$341 $1,811 4.1
$233 $2,044
$204 $2,248
$179 $2,427
$105 $2,532
$156 $2,688
-$98 $2,590
$137 $2,727
$119 $2,846
$285 $3,131
$104 $3,235
$91 $3,326
$80 $3,406
$70 $3,476
$3,476
n Diesel Engine Gas
$/Age Cum$ PaybkAge
$866
$757
$150
$662
$579
$341
$506
$443
$387
$105
$339
-$98
$296
$259
$285
$227
$198
$173
$152
$866
$1,623
$1,773
$2,435
$3,014
$3,355 4.3
$3,861
$4,304
$4,691
$4,796
$5,135
$5,037
$5,333
$5,592
$5,877
$6,104
$6,302
$6,475
$6,627
$6,627
Var Disp Engine Clean Di
$/Age Cum$ PaybkAge
$662 $662
$579 $1,241
$150 $1,391
$507 $1,898
$443 $2,341 3.3
$341 $2,682
$387 $3,069
$339 $3,408
$296 $3,704
$105 $3,809
$259 $4,068
-$98 $3,970
$227 $4,197
$198 $4,395
$285 $4,680
$173 $4,853
$152 $5,005
$133 $5,138
$116 $5,254
$5,254
3sel Var Disp Engine
$/Age Cum$ PaybkAge
$1,040 $1,040
$909 $1,949
$150 $2,099
$795 $2,894
$695 $3,589
$341 $3,930 4.2
$608 $4,538
$532 $5,070
$465 $5,535
$105 $5,640
$407 $6,047
-$98 $5,949
$356 $6,305
$311 $6,616
$285 $6,901
$272 $7,173
$238 $7,411
$208 $7,619
$182 $7,801
$7,801
N-3
-------
Appendix N
Calculations of Payback by Technology
Table N1-5: Large 4WD SUV Mild Hydraulic Hybrid - Engine Off |
Age
1
2
2.08
3
4
4.49
5
6
7
7.35
8
8.44
9
10
10.89
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$272 $272
$238 $510
$150 $660
$208 $868
$182 $1,050
$341 $1,391 4.4
$159 $1,550
$139 $1,689
$122 $1,811
$105 $1,916
$106 $2,022
-$98 $1,924
$93 $2,017
$81 $2,098
$285 $2,383
$71 $2,454
$62 $2,516
$54 $2,570
$48 $2,618
$2,618
Clean Diesel Engine
$/Age Cum$ PaybkAge
$755 $755
$660 $1,415
$150 $1,565
$577 $2,142
$505 $2,647
$341 $2,988
$442 $3,430 4.5
$386 $3,816
$338 $4,154
$105 $4,259
$295 $4,554
-$98 $4,456
$258 $4,714
$226 $4,940
$285 $5,225
$198 $5,423
$173 $5,596
$151 $5,747
$132 $5,879
$5,879
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$483 $483
$422 $905
$150 $1,055
$369 $1,424
$323 $1,747
$341 $2,088 4.1
$282 $2,370
$247 $2,617
$216 $2,833
$105 $2,938
$189 $3,127
-$98 $3,029
$165 $3,194
$144 $3,338
$285 $3,623
$126 $3,749
$110 $3,859
$97 $3,956
$84 $4,040
$4,040
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$907 $907
$793 $1,700
$150 $1,850
$693 $2,543
$607 $3,150
$341 $3,491
$530 $4,021 4.5
$464 $4,485
$406 $4,891
$105 $4,996
$355 $5,351
-$98 $5,253
$310 $5,563
$271 $5,834
$285 $6,119
$237 $6,356
$208 $6,564
$182 $6,746
$159 $6,905
$6,905
Table N1-6: Large 4WD SUV Mild Hydraulic Hybrid - Engine Off
Reduced Roadload
Age
1
2
2.08
3
4
4.49
5
6
7
7.35
8
8.44
9
10
10.89
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$458 $458
$400 $858
$150 $1,008
$350 $1,358
$306 $1,664 3.6
$341 $2,005
$268 $2,273
$234 $2,507
$205 $2,712
$105 $2,817
$179 $2,996
-$98 $2,898
$157 $3,055
$137 $3,192
$285 $3,477
$120 $3,597
$105 $3,702
$92 $3,794
$80 $3,874
$3,874
Clean Diesel Engine
$/Age Cum$ PaybkAge
$893
$781
$150
$683
$597
$341
$522
$457
$400
$105
$349
-$98
$306
$267
$285
$234
$204
$179
$156
$893
$1,674
$1,824
$2,507
$3,104
$3,445 4.2
$3,967
$4,424
$4,824
$4,929
$5,278
$5,180
$5,486
$5,753
$6,038
$6,272
$6,476
$6,655
$6,811
$6,811
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$686 $686
$600 $1,286
$150 $1,436
$525 $1,961
$459 $2,420 3.2
$341 $2,761
$401 $3,162
$351 $3,513
$307 $3,820
$105 $3,925
$269 $4,194
-$98 $4,096
$235 $4,331
$205 $4,536
$285 $4,821
$180 $5,001
$157 $5,158
$137 $5,295
$120 $5,415
$5,415
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$1,055 $1,055
$923 $1,978
$150 $2,128
$807 $2,935
$706 $3,641
$341 $3,982 4.1
$617 $4,599
$540 $5,139
$472 $5,611
$105 $5,716
$413 $6,129
-$98 $6,031
$361 $6,392
$316 $6,708
$285 $6,993
$276 $7,269
$241 $7,510
$211 $7,721
$185 $7,906
$7,906
N-4
-------
Appendix N
Calculations of Payback by Technology
Table N1-7: Large 4WD SUV Full Hydraulic Hybrid - Engine On |
Age
1
2
2.08
3
4
4.49
5
6
7
7.35
8
8.44
9
10
10.89
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$286 $286
$250 $536
$150 $686 2.0
$218 $904
$191 $1,095
$341 $1,436
$167 $1,603
$146 $1,749
$128 $1,877
$105 $1,982
$112 $2,094
-$98 $1,996
$98 $2,094
$85 $2,179
$285 $2,464
$75 $2,539
$65 $2,604
$57 $2,661
$50 $2,711
$2,711
Clean Diesel Engine
$/Age Cum$ PaybkAge
$740 $740
$647 $1,387
$150 $1,537
$566 $2,103
$495 $2,598 3.2
$341 $2,939
$433 $3,372
$378 $3,750
$331 $4,081
$105 $4,186
$289 $4,475
-$98 $4,377
$253 $4,630
$221 $4,851
$285 $5,136
$194 $5,330
$169 $5,499
$148 $5,647
$129 $5,776
$5,776
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$481 $481
$421 $902
$150 $1,052
$368 $1,420 2.1
$322 $1,742
$341 $2,083
$281 $2,364
$246 $2,610
$215 $2,825
$105 $2,930
$188 $3,118
-$98 $3,020
$165 $3,185
$144 $3,329
$285 $3,614
$126 $3,740
$110 $3,850
$96 $3,946
$84 $4,030
$4,030
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$901 $901
$788 $1,689
$150 $1,839
$689 $2,528
$603 $3,131 3.3
$341 $3,472
$527 $3,999
$461 $4,460
$403 $4,863
$105 $4,968
$353 $5,321
-$98 $5,223
$308 $5,531
$270 $5,801
$285 $6,086
$236 $6,322
$206 $6,528
$180 $6,708
$158 $6,866
$6,866
Table N1 :8 Large 4WD SUV Full Hydraulic Hybrid - Engine On
Reduced Roadload
Age
1
2
2.08
3
4
4.49
5
6
7
7.35
8
8.44
9
10
10.89
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$496 $496
$434 $930 1.6
$150 $1,080
$380 $1,460
$332 $1,792
$341 $2,133
$290 $2,423
$254 $2,677
$222 $2,899
$105 $3,004
$194 $3,198
-$98 $3,100
$170 $3,270
$149 $3,419
$285 $3,704
$130 $3,834
$114 $3,948
$99 $4,047
$87 $4,134
$4,134
Clean Diesel Engine
$/Age Cum$ PaybkAge
$917 $917
$802 $1,719
$150 $1,869
$701 $2,570 2.8
$613 $3,183
$341 $3,524
$536 $4,060
$469 $4,529
$410 $4,939
$105 $5,044
$359 $5,403
-$98 $5,305
$314 $5,619
$274 $5,893
$285 $6,178
$240 $6,418
$210 $6,628
$183 $6,811
$160 $6,971
$6,971
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$703 $703
$615 $1,318 1.9
$150 $1,468
$537 $2,005
$470 $2,475
$341 $2,816
$411 $3,227
$359 $3,586
$314 $3,900
$105 $4,005
$275 $4,280
-$98 $4,182
$240 $4,422
$210 $4,632
$285 $4,917
$184 $5,101
$161 $5,262
$141 $5,403
$123 $5,526
$5,526
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$1,067 $1,067
$934 $2,001
$150 $2,151
$816 $2,967 3.0
$714 $3,681
$341 $4,022
$624 $4,646
$546 $5,192
$478 $5,670
$105 $5,775
$418 $6,193
-$98 $6,095
$365 $6,460
$319 $6,779
$285 $7,064
$279 $7,343
$244 $7,587
$214 $7,801
$187 $7,988
$7,988
N-5
-------
Appendix N
Calculations of Payback by Technology
Table N1-9: Large 4WD SUV Full Hydraulic Hybrid - Engine Off |
Age
1
2
2.08
3
4
4.49
5
6
7
7.35
8
8.44
9
10
10.89
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$492 $492
$430 $922 1.2
$150 $1,072
$376 $1,448
$329 $1,777
$341 $2,118
$288 $2,406
$251 $2,657
$220 $2,877
$105 $2,982
$192 $3,174
-$98 $3,076
$168 $3,244
$147 $3,391
$285 $3,676
$129 $3,805
$113 $3,918
$98 $4,016
$86 $4,102
$4,102
Clean Diesel Engine
$/Age Cum$ PaybkAge
$925 $925
$809 $1,734
$150 $1,884
$707 $2,591 2.5
$619 $3,210
$341 $3,551
$541 $4,092
$473 $4,565
$414 $4,979
$105 $5,084
$362 $5,446
-$98 $5,348
$316 $5,664
$277 $5,941
$285 $6,226
$242 $6,468
$212 $6,680
$185 $6,865
$162 $7,027
$7,027
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$559 $559
$489 $1,048
$150 $1,198 2.0
$427 $1,625
$374 $1,999
$341 $2,340
$327 $2,667
$286 $2,953
$250 $3,203
$105 $3,308
$219 $3,527
-$98 $3,429
$191 $3,620
$167 $3,787
$285 $4,072
$146 $4,218
$128 $4,346
$112 $4,458
$98 $4,556
$4,556
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$1,010 $1,010
$883 $1,893
$150 $2,043
$772 $2,815 2.9
$676 $3,491
$341 $3,832
$591 $4,423
$517 $4,940
$452 $5,392
$105 $5,497
$395 $5,892
-$98 $5,794
$346 $6,140
$302 $6,442
$285 $6,727
$264 $6,991
$231 $7,222
$202 $7,424
$177 $7,601
$7,601
Table N1-10: Large 4WD SUV Full Hydraulic Hybrid - Engine Off
Reduced Roadload
Age
1
2
2.08
3
4
4.49
5
6
7
7.35
8
8.44
9
10
10.89
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$731 $731
$639 $1,370 1.1
$150 $1,520
$559 $2,079
$489 $2,568
$341 $2,909
$427 $3,336
$374 $3,710
$327 $4,037
$105 $4,142
$286 $4,428
-$98 $4,330
$250 $4,580
$219 $4,799
$285 $5,084
$191 $5,275
$167 $5,442
$146 $5,588
$128 $5,716
$5,716
Clean Diesel Engine
$/Age Cum$ PaybkAge
$1,110
$971
$150
$849
$743
$341
$650
$568
$497
$105
$434
-$98
$380
$332
$285
$291
$254
$222
$194
$1,110
$2,081
$2,231
$3,080 2.3
$3,823
$4,164
$4,814
$5,382
$5,879
$5,984
$6,418
$6,320
$6,700
$7,032
$7,317
$7,608
$7,862
$8,084
$8,278
$8,278
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$799 $799
$699 $1,498 1.7
$150 $1,648
$611 $2,259
$535 $2,794
$341 $3,135
$468 $3,603
$409 $4,012
$358 $4,370
$105 $4,475
$313 $4,788
-$98 $4,690
$273 $4,963
$239 $5,202
$285 $5,487
$209 $5,696
$183 $5,879
$160 $6,039
$140 $6,179
$6,179
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$1,178 $1,178
$1,031 $2,209
$150 $2,359
$901 $3,260 2.7
$788 $4,048
$341 $4,389
$689 $5,078
$603 $5,681
$527 $6,208
$105 $6,313
$461 $6,774
-$98 $6,676
$403 $7,079
$353 $7,432
$285 $7,717
$308 $8,025
$270 $8,295
$236 $8,531
$206 $8,737
$8,737
N-6
-------
Appendix N
Calculations of Payback by Technology
Table N2-1 : Midsize Car Conventional Transmission
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
Base Base Base
Clean Diesel Engine
$/Age Cum$ PaybkAge
$246 $246
$219 $465
$195 $660
$173 $833
$154 $987
$136 $1,123
$121 $1,244 6.7
$108 $1,352
$96 $1,448
$85 $1,533
$76 $1,609
$67 $1,676
$60 $1,736
$53 $1,789
$1,789
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$161 $161
$143 $304
$127 $431 2.9
$113 $544
$100 $644
$89 $733
$79 $812
$70 $882
$63 $945
$56 $1,001
$49 $1,050
$44 $1,094
$39 $1,133
$35 $1,168
$1,168
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$346 $346
$307 $653
$273 $926
$243 $1,169
$216 $1,385
$191 $1,576
$170 $1,746 6.2
$151 $1,897
$134 $2,031
$119 $2,150
$106 $2,256
$94 $2,350
$84 $2,434
$74 $2,508
$2,508
Table N2-2: Midsize Car Conventional Transmission
Reduced Roadload
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$54 $54
$48 $102
$42 $144
$38 $182
$33 $215 4.8
$30 $245
$26 $271
$23 $294
$21 $315
$18 $333
$16 $349
$15 $364
$13 $377
$12 $389
$389
Clean Diesel Engine
$/Age Cum$ PaybkAge
$292 $292
$259 $551
$230 $781
$205 $986
$182 $1,168
$162 $1,330
$144 $1,474 6.6
$128 $1,602
$113 $1,715
$101 $1,816
$89 $1,905
$79 $1,984
$71 $2,055
$63 $2,118
$2,118
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$219 $219
$195 $414
$173 $587
$154 $741 3.2
$137 $878
$121 $999
$108 $1,107
$96 $1,203
$85 $1,288
$76 $1,364
$67 $1,431
$60 $1,491
$53 $1,544
$47 $1,591
$1,591
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$390 $390
$347 $737
$308 $1,045
$274 $1,319
$243 $1,562
$216 $1,778
$192 $1,970 6.2
$171 $2,141
$152 $2,293
$135 $2,428
$120 $2,548
$106 $2,654
$94 $2,748
$84 $2,832
$2,832
N-7
-------
Appendix N
Calculations of Payback by Technology
Table N2-3: Midsize Car Mild Hydraulic Hybrid - Engine On
Age
1
2
2.81
3
4
5
6
6.08
7
8
9
10
11
11.51
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$91 $91
$81 $172
$122 $352
$72 $366
$64 $430
$57 $487
$50 $537
$277 $818
$45 $859
$40 $899
$35 $934
$107 $1,041 9.6
$28 $1,069
-$68 $1,001
$25 $1,026
$22 $1,048
$20 $1,068
$1,068
Clean Diesel Engine
$/Age Cum$ PaybkAge
$357 $357
$317 $674
$122 $1,024
$282 $1,078
$251 $1,329
$223 $1,552
$198 $1,750
$277 $2,041
$176 $2,203 6.9
$156 $2,359
$139 $2,498
$199 $2,697
$110 $2,807
-$68 $2,739
$97 $2,836
$86 $2,922
$77 $2,999
$2,999
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$252 $252
$224 $476
$122 $759
$199 $797
$177 $974
$157 $1,131
$140 $1,271
$277 $1,558 6.0
$124 $1,672
$110 $1,782
$98 $1,880
$162 $2,042
$77 $2,119
-$68 $2,051
$69 $2,120
$61 $2,181
$54 $2,235
$2,235
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$442 $442
$393 $835
$122 $1,240
$349 $1,306
$310 $1,616
$275 $1,891
$245 $2,136
$277 $2,430
$217 $2,630 6.7
$193 $2,823
$172 $2,995
$228 $3,223
$135 $3,358
-$68 $3,290
$120 $3,410
$107 $3,517
$95 $3,612
$3,612
Table N2-4: Midsize Car Mild Hydraulic Hybrid - Engine On
Reduced Roadload
Age
1
2
2.81
3
4
5
6
6.08
7
8
9
10
11
11.51
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$148 $148
$131 $279
$122 $495
$116 $517
$103 $620
$92 $712
$82 $794
$277 $1,077
$73 $1,144
$64 $1,208
$57 $1,265 8.0
$126 $1,391
$45 $1,436
-$68 $1,368
$40 $1,408
$36 $1,444
$32 $1,476
$1,476
Clean Diesel Engine
$/Age Cum$ PaybkAge
$403 $403
$358 $761
$122 $1,141
$318 $1,201
$283 $1,484
$251 $1,735
$223 $1,958
$277 $2,251
$198 $2,433 6.8
$176 $2,609
$157 $2,766
$214 $2,980
$124 $3,104
-$68 $3,036
$110 $3,146
$98 $3,244
$87 $3,331
$3,331
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$316 $316
$281 $597
$122 $922
$250 $970
$222 $1,192
$197 $1,389
$175 $1,564
$277 $1,853 6.0
$156 $1,997
$138 $2,135
$123 $2,258
$184 $2,442
$97 $2,539
-$68 $2,471
$86 $2,557
$76 $2,633
$68 $2,701
$2,700
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$492 $492
$437 $929
$122 $1,365
$388 $1,439
$345 $1,784
$306 $2,090
$272 $2,362
$277 $2,658
$242 $2,881 6.6
$215 $3,096
$191 $3,287
$245 $3,532
$151 $3,683
-$68 $3,615
$134 $3,749
$119 $3,868
$106 $3,974
$3,974
N-8
-------
Appendix N
Calculations of Payback by Technology
Table N2-5: Midsize Car Mild Hydraulic Hybrid - Engine Off
Age
1
2
2.81
3
4
5
6
6.08
7
8
9
10
11
11.51
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$127 $127
$113 $240
$122 $444
$101 $463
$89 $552
$79 $631
$70 $701
$277 $983
$63 $1,041 6.5
$56 $1,097
$49 $1,146
$119 $1,265
$39 $1,304
-$68 $1,236
$35 $1,271
$31 $1,302
$27 $1,329
$1,329
Clean Diesel Engine
$/Age Cum$ PaybkAge
$375 $375
$333 $708
$122 $1,070
$296 $1,126
$263 $1,389
$234 $1,623
$208 $1,831
$277 $2,123
$184 $2,292 6.5
$164 $2,456
$146 $2,602
$205 $2,807
$115 $2,922
-$68 $2,854
$102 $2,956
$91 $3,047
$81 $3,128
$3,128
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$270 $270
$240 $510
$122 $805
$213 $845
$190 $1,035
$169 $1,204
$150 $1,354
$277 $1,642 6.0
$133 $1,764
$118 $1,882
$105 $1,987
$169 $2,156
$83 $2,239
-$68 $2,171
$74 $2,245
$65 $2,310
$58 $2,368
$2,368
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$455 $455
$405 $860
$122 $1,274
$360 $1,342
$319 $1,661
$284 $1,945
$252 $2,197
$277 $2,492
$224 $2,698 6.5
$199 $2,897
$177 $3,074
$232 $3,306
$140 $3,446
-$68 $3,378
$124 $3,502
$110 $3,612
$98 $3,710
$3,710
Table N2-6: Midsize Car Mild Hydraulic Hybrid - Engine Off
Reduced Roadload
Age
1
2
2.81
3
4
5
6
6.08
7
8
9
10
11
11.51
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$187 $187
$166 $353
$122 $475
$148 $623
$131 $754
$117 $871
$104 $975
$277 $1,252 6.1
$92 $1,344
$82 $1,426
$73 $1,499
$140 $1,639
$57 $1,696
-$68 $1,628
$51 $1,679
$45 $1,724
$40 $1,764
$1,764
Clean Diesel Engine
$/Age Cum$ PaybkAge
$426 $426
$378 $804
$122 $926
$336 $1,262
$299 $1,561
$265 $1,826
$236 $2,062
$277 $2,339
$209 $2,548 6.4
$186 $2,734
$165 $2,899
$222 $3,121
$130 $3,251
-$68 $3,183
$116 $3,299
$103 $3,402
$92 $3,494
$3,494
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$336 $336
$298 $634
$122 $756
$265 $1,021
$235 $1,256
$209 $1,465
$186 $1,651 5.7
$277 $1,928
$165 $2,093
$147 $2,240
$130 $2,370
$191 $2,561
$103 $2,664
-$68 $2,596
$91 $2,687
$81 $2,768
$72 $2,840
$2,840
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$506 $506
$450 $956
$122 $1,078
$400 $1,478
$355 $1,833
$315 $2,148
$280 $2,428
$277 $2,705
$249 $2,954 6.4
$221 $3,175
$197 $3,372
$250 $3,622
$155 $3,777
-$68 $3,709
$138 $3,847
$122 $3,969
$109 $4,078
$4,078
N-9
-------
Appendix N
Calculations of Payback by Technology
Table N2-7: Midsize Car Full Hydraulic Hybrid - Engine On
Age
1
2
2.81
3
4
5
6
6.08
7
8
9
10
11
11.51
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$170 $170
$151 $321
$122 $443
$134 $577
$119 $696
$106 $802
$94 $896
$277 $1,173 6.1
$84 $1,257
$74 $1,331
$66 $1,397
$134 $1,531
$52 $1,583
-$68 $1,515
$46 $1,561
$41 $1,602
$37 $1,639
$1,639
Clean Diesel Engine
$/Age Cum$ PaybkAge
$373 $373
$332 $705
$122 $827
$295 $1,122
$262 $1,384
$233 $1,617
$207 $1,824
$277 $2,101
$184 $2,285
$163 $2,448 7.1
$145 $2,593
$204 $2,797
$114 $2,911
-$68 $2,843
$102 $2,945
$90 $3,035
$80 $3,115
$3,115
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$302 $302
$268 $570
$122 $692
$238 $930
$212 $1,142
$188 $1,330
$167 $1,497 6.0
$277 $1,774
$148 $1,922
$132 $2,054
$117 $2,171
$179 $2,350
$92 $2,442
-$68 $2,374
$82 $2,456
$73 $2,529
$65 $2,594
$2,594
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$451 $451
$401 $852
$122 $974
$356 $1,330
$316 $1,646
$281 $1,927
$250 $2,177
$277 $2,454
$222 $2,676
$197 $2,873 7.1
$175 $3,048
$231 $3,279
$138 $3,417
-$68 $3,349
$123 $3,472
$109 $3,581
$97 $3,678
$3,678
Table N2-8: Midsize Car Full Hydraulic Hybrid - Engine On
Reduced Roadload
Age
1
2
2.81
3
4
5
6
6.08
7
8
9
10
11
11.51
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$240 $240
$213 $453
$122 $575
$189 $764
$168 $932
$149 $1,081
$133 $1,214
$277 $1,491 6.0
$118 $1,609
$105 $1,714
$93 $1,807
$158 $1,965
$73 $2,038
-$68 $1,970
$65 $2,035
$58 $2,093
$51 $2,144
$2,144
Clean Diesel Engine
$/Age Cum$ PaybkAge
$427 $427
$380 $807
$122 $929
$337 $1,266
$300 $1,566
$266 $1,832
$237 $2,069
$277 $2,346
$210 $2,556 6.8
$187 $2,743
$166 $2,909
$223 $3,132
$131 $3,263
-$68 $3,195
$116 $3,311
$103 $3,414
$92 $3,506
$3,506
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$377 $377
$335 $712
$122 $834
$298 $1,132
$264 $1,396
$235 $1,631
$209 $1,840 5.3
$277 $2,117
$185 $2,302
$165 $2,467
$146 $2,613
$205 $2,818
$116 $2,934
-$68 $2,866
$103 $2,969
$91 $3,060
$81 $3,141
$3,141
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$506 $506
$449 $955
$122 $1,077
$399 $1,476
$355 $1,831
$315 $2,146
$280 $2,426
$277 $2,703
$249 $2,952 6.8
$221 $3,173
$196 $3,369
$250 $3,619
$155 $3,774
-$68 $3,706
$138 $3,844
$122 $3,966
$109 $4,075
$4,075
N-10
-------
Appendix N
Calculations of Payback by Technology
Table N2-9: Midsize Car Full Hydraulic Hybrid - Engine Off
Age
1
2
2.81
3
4
5
6
6.08
7
8
9
10
11
11.51
12
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$291 $291
$258 $549
$122 $671
$229 $900
$204 $1,104
$181 $1,285 4.2
$161 $1,446
$277 $1,723
$143 $1,866
$127 $1,993
$113 $2,106
$176 $2,282
$89 $2,371
-$68 $2,303
$79 $2,382
$70 $2,452
$62 $2,514
$2,514
Clean Diesel Engine
$/Age Cum$ PaybkAge
$458 $458
$407 $865
$122 $987
$362 $1,349
$322 $1,671
$286 $1,957
$254 $2,211
$277 $2,488 6.0
$226 $2,714
$200 $2,914
$178 $3,092
$233 $3,325
$141 $3,466
-$68 $3,398
$125 $3,523
$111 $3,634
$99 $3,733
$3,733
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$317 $317
$282 $599
$122 $721
$250 $971
$222 $1,193
$198 $1,391
$176 $1,567 5.8
$277 $1,844
$156 $2,000
$139 $2,139
$123 $2,262
$185 $2,447
$97 $2,544
-$68 $2,476
$86 $2,562
$77 $2,639
$68 $2,707
$2,707
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$489 $489
$434 $923
$122 $1,045
$386 $1,431
$343 $1,774
$305 $2,079
$271 $2,350
$277 $2,627
$240 $2,867 6.4
$214 $3,081
$190 $3,271
$244 $3,515
$150 $3,665
-$68 $3,597
$133 $3,730
$118 $3,848
$105 $3,953
$3,953
Table N2-10: Midsize Car Full Hydraulic Hybrid - Engine Off
Reduced Roadload
Age
1
2
2.81
3
4
5
6
6.08
7
8
9
10
11
12
11.51
13
14
MOBILE6 MOBILE6
LDVVMT LDTVMT
14,910 19,978
14,174 18,695
13,475 17,494
12,810 16,371
12,178 15,319
11,577 14,335
11,006 13,414
10,463 12,553
9,947 11,746
9,456 10,992
8,989 10,286
8,546 9,625
8,124 9,007
7,723 8,428
Conv Gas Engine
$/Age Cum$ PaybkAge
$374 $374
$332 $706
$122 $828
$295 $1,123
$262 $1,385 3.8
$233 $1,618
$207 $1,825
$277 $2,102
$184 $2,286
$163 $2,449
$145 $2,594
$204 $2,798
$115 $2,913
$102 $3,015
-$68 $2,947
$90 $3,037
$80 $3,117
$3,117
Clean Diesel Engine
$/Age Cum$ PaybkAge
$517 $517
$460 $977
$122 $1,099
$408 $1,507
$363 $1,870
$322 $2,192
$286 $2,478
$277 $2,755 6.0
$254 $3,009
$226 $3,235
$201 $3,436
$254 $3,690
$159 $3,849
$141 $3,990
-$68 $3,922
$125 $4,047
$111 $4,158
$4,158
Gas Var Disp Engine
$/Age Cum$ PaybkAge
$395 $395
$351 $746
$122 $868
$312 $1,180
$277 $1,457
$246 $1,703
$219 $1,922 5.1
$277 $2,199
$195 $2,394
$173 $2,567
$154 $2,721
$212 $2,933
$121 $3,054
$108 $3,162
-$68 $3,094
$96 $3,190
$85 $3,275
$3,275
Clean Diesel Var Disp Engine
$/Age Cum$ PaybkAge
$545 $545
$484 $1,029
$122 $1,151
$430 $1,581
$382 $1,963
$340 $2,303
$302 $2,605
$277 $2,882
$268 $3,150 6.3
$238 $3,388
$212 $3,600
$263 $3,863
$167 $4,030
$148 $4,178
-$68 $4,110
$132 $4,242
$117 $4,359
$4,359
N-11
-------
APPENDIX O
Appendix O: Review by External Organizations
A preliminary draft of this progress report was distributed to six external organizations for their
technical review: three private sector companies with which EPA has cooperative research and
development agreements (Ford Motor Company, Eaton Corporation, and Parker-Hannifin), two
private contractors which have contracts with EPA and which are experts on various aspects of
the new technologies included in this report (FEV of America and Southwest Research Institute),
and a professor at Michigan State University. These technical reviews were considered to be
confidential to allow frank feedback, and this section will summarize the most important
comments but will not link them to specific organizations.
1. The comments provided to EPA were generally very favorable. One of the more extensive
reviews stated: "Good overall study/analysis. The approaches taken to the areas the study
chooses to address are appropriate and probably sufficient for a generalized look at this topic in a
mature state." Another commenter "found the document to be comprehensive and insightful."
A third reviewer stated: "The conclusions reached regarding fuel efficiency improvements and
reduced operating costs are based upon sound engineering approaches including modeling and
simulation based upon real test data." No commenter suggested that EPA should not release the
study.
2. One reviewer cited the report's assumption of a long-term, high economy-of-scale scenario
for cost projections, and stated that: "The simplicity of a mature cost/payback (benefit) analysis
as done by EPA leaves much of the practical considerations of moving to a hydraulic hybrid
drivetrain un-studied and is therefore not a sufficient basis to justify the technology." A second
commenter said that "[t]he report does not explicitly define what annual volumes are used as the
basis for the cost estimates." In response to these comments, EPA has added text in the
Abstract, Executive Summary, and Section 6 to clarify the underlying high economy-of-scale
assumption (when annual component production volumes first reach one million units) and to
recognize that the projections do not account for many costs that would be borne during a
transition period.
3. One commenter suggested that the cost projections might be too conservative in the long run:
"The projections for fuel economy improvement seem to be somewhat conservative considering
the current level of technical development of the hardware. As with all automotive technologies,
high volume production can be expected to yield significant additional improvements in
efficiency and reduction in cost. The net results will be greater vehicle lifetime savings and
reduced payback time." A second reviewer stated: "[t]he global marketplace, especially in the
very competitive auto industry, is a place where cost optimization and reduction is the key to
success... .Significant advances in the technologies and manufacturing processes associated with
these systems could yield lower costs and thus lower prices to the end user. Although it is not
possible to accurately predict how many of these advances will occur and what their net effects
will be, I am confident that advances will be made." In response to these comments, EPA has
added text in the Abstract, Executive Summary, and Section 6 to recognize that the projections
do not account for potential long-term cost savings if and when such technologies become
mature and sustainable.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page O-l
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APPENDIX O
4. One reviewer stated that "[T]he addition of sensitivity analyses for the various options has the
potential to add value to the understanding of their commercial viability." This same reviewer
also offered a specific set of alternative cost assumptions (based on annual component
production volumes of 500,000 per year) for hydraulic hybrid drivetrains that differed from EPA
cost assumptions used in the body of the report (based on annual component production volumes
of one million) in five areas that are summarized in Table O-l below.
Table O-l: Alternative Cost Assumptions for the
Hydraulic Hybrid Drivetrain Sensitivity Analysis
Hydraulic
Hybrid Cost
Area
Pump Motors
Controls/Sensors
Accumulators
Hoses/Fittings
Oil
Cost
Assumption
in Section 6
$9.1 I/kg
Included in
pump motor
cost
$10.00/kg
100%
$3.00/kg
Alternative Cost
Assumption
Suggested by
Reviewer
$10.45/kg
+$200 SUV &
+$100 car
$13.00/kg
90%ofEPA's
cost
$2.00/kg
Rationale for Alternative
Assumption
Pump motor more like transmission
($10.45/kg) complexity than engine
($9.1 I/kg) complexity
Reviewer assumed cost of controls and
sensors not included. Also, more
lengthy wiring harness is needed for
hydraulic system than a normal
transmission.
Based on current manufacturing
techniques and aggressive "learning
curve" for high volume.
Higher mass than projected by EPA,
but lower cost per unit mass.
Based on reviewer experience with
fluids.
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page O-2
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APPENDIX O
These alternative cost assumptions provide a basis for a sensitivity analysis of the cost
projections for the technology packages involving hydraulic hybrid drivetrains. The one case
where EPA modified the cost assumptions suggested by the commenter was with respect to
controls and sensors. The reviewer stated that: "The inclusion of an electronic control and the
required incremental sensors is not apparent in the report." EPA did include controls and sensors
in the hydraulic hybrid designs described in Section 3, but for purposes of the sensitivity
analysis, EPA included the full $200 cost increment suggested by the commenter for controls
and sensors for the 4WD large SUV hydraulic hybrid designs and one-half of this, or a $100 cost
increment, for controls and sensors for the midsize car hydraulic hybrid drivetrains. Table O-2
shows the projected incremental vehicle costs, cost per percent fuel economy improvement,
consumer payback, and vehicle lifetime savings for the 4WD large SUV technology packages
involving hydraulic hybrid drivetrains under this alternative scenario compared to the
conventional 4WD large SUV that is used as the baseline 4WD large SUV throughout this
report.
Table O-2: Key Economic Projections for Large 4WD SUV Under the
Hydraulic Hybrid Drivetrain Sensitivity Analysis
Large Sport Utility Vehicle
(4WD)
New Vehicle Cost Increase ($)
//
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cosf Increase / FE Improvement ($ per %)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cosf Payback to Consumer(s) (Years)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Net Lifetime Savings to Consumer(s) ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
base
$1,668
$532
$2,195
$1,784
$3,446
$2,285
$3,950
I $1,799
! $3,463
! $2,302
I $3,967
$1,218 I
$2,883 |
$1,721 !
$3,387 I
$1,241
$2,907
$1,750
$3,415
base
$45
$36
$39
$135
$60
$74
$49
i $109
| $57
j $70
< $48
$70 j
$49 |
$53 ;
$41
$36
$34
$43
$34
base
3.6
2.3
3.5
9.8
5.3
5.0
5.0
i 6.9
I 5.1
I 4.9
I 4.9
4.2 [
4.4 I
3.9 I
4.4 |
2.5
3.5
3.3
3.9
base
$2,060
$1,175
$2,738
$492
$2,270
$1,604
$2,855
j $819
; $2,416
! $1,738
! $2,938
$1,493 j
$2,893 ]
$2,309 !
$3,479 !
$2,861
$4,120
$2,806
$4,186
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page O-3
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APPENDIX O
Table O-3 shows the differences in the key economic projections between this sensitivity case
and the standard case summarized in Table ES-1 for 4WD large SUVs with hydraulic hybrid
drivetrains.
Table O-3: Change in the Key Economic Projections for the Sensitivity Case
Relative to the Standard Case for Large 4WD SUV
Large Sport Utility Vehicle
(4WD) '
New Vehicle Cost Increase ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cosf Increase / FE Improvement ($ per %)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cosf Payback to Consumers) (Years)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Wef Lifetime Savings to Consumers) ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
base
$0
$0
$0
base
$0
$0
$0
base
0.0
0.0
0.0
base
$0
$0
$0
$463 ! $463
$463 ! $464
$463 { $464
$463 1 $463
$35 j $28
$8 | $8
$15 ! $14
$6 | $6
5 ] 2.5
0.7 I 0.6
0.8 I 0.8
0.5 | 0.4
-$463 j -$463
-$463 • -$464
-$463 ! -$464
-$463 ! -$463
$666
$666
$666
$666
$38
$11
$20
$8
2.2
1.2
1.8
1.1
-$666
-$666
-$666
-$666
$666
$666
$666
$666
$19
$8
$17
$7
1.3
1.0
1.3
1.0
-$666
-$666
-$666
-$666
For a 4WD large SUV, this alternative cost scenario adds about $460 for a mild hydraulic hybrid
drivetrain, and about $670 for a full hydraulic hybrid drivetrain (and reduces the vehicle lifetime
savings by the same amount). These higher incremental costs increase the cost per percent fuel
economy improvement, and the consumer payback period, the latter generally on the order of
about one year. The best payback for a 4WD large SUV hydraulic hybrid technology package in
this alternative cost scenario, involving a conventional gasoline engine with full hydraulic hybrid
drivetrain and engine-off strategy, is 2.5 years, compared to a payback of 1.2 years with the
hydraulic hybrid cost assumptions in Section 6.
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page O-4
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APPENDIX O
For the midsize car technology packages involving hydraulic hybrid drivetrains, Table O-4
shows the projected incremental vehicle costs, cost per percent fuel economy improvement,
consumer payback, and vehicle lifetime savings under this alternative scenario compared to the
conventional midsize car that is used as the baseline midsize car throughout this report.
Table O-4: Key Economic Projections for Midsize Car Under the
Hydraulic Hybrid Drivetrain Sensitivity Analysis
Midsize Car
(2WD)
New Vehicle Cost Increase ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cost Increase I FE Improvement ($ per %)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cost Payback to Consumers) (Years)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Net Lifetime Savings to Consumers) ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
base
$1,206
$412
$1,613
base
$32
$19
$26
base
6.7
2.9
6.2
base
$583
$756
$895
$1,263
$2,448
$1,639
$2,833
$105
$36
$40
$29
#N/A
8.6
6.7
8.1
-$195
$551
$596
$779
$1,274
$2,461
$1,652
$2,847
$72
$34
$37
$27
12.1
8.0
6.2
7.7
$55
$667
$716
$863
$1,551
$2,744
$1,930
$3,130
$64
$38
$37
$31
11.9
9.7
7.1
9.4
$88
$371
$664
$548
$1,570
$2,767
$1,963
$3,159
$31
$26
$34
$26
6.0
7.3
6.8
8.4
$944
$966
$744
$794
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page O-5
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APPENDIX O
Table O-5 shows the differences in the key economic projections between this sensitivity case
and the standard case summarized in Table ES-2 for midsize cars with hydraulic hybrid
drivetrains.
Table O-5: Change in the Key Economic Parameters for the Sensitivity Case
Relative to the Standard Case for Midsize Car
Midsize Car
(2WD)
c/
New Vehicle Cost Increase ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cosf Increase / FE Improvement ($ per %)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Cosf Payback to Consumers) (Years)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
Wef Lifetime Savings to Consumers) ($)
Conventional Gasoline Engine
Clean Diesel Engine
Gasoline Variable Displacement Engine
Clean Diesel Variable Displacement Engine
base
$0
$0
$0
base
$0
$0
$0
base
0.0
0.0
0.0
base
$0
$0
$0
$265
$266
$266
$266
$22
$4
$7
$3
#N/A
1.7
0.7
1.4
-$265
-$266
-$266
-$266
$265
$266
$266
$266
$15
$4
$6
$3
5.6
1.5
0.2
1.2
-$265
-$266
-$266
-$266
$437
$437
$437
$438
$18
$6
$8
$4
5.8
2.6
1.1
2.3
-$437
-$437
-$437
-$438
$437
$437
$438
$437
$9
$4
$8
$4
1.8
1.3
1.0
2.0
-$437
-$437
-$438
-$437
For a midsize car, this alternative cost scenario adds about $270 for a mild hydraulic hybrid
drivetrain, and about $440 for a full hydraulic hybrid drivetrain (and reduces the vehicle lifetime
savings by the same amount). These higher incremental costs increase the cost per percent fuel
economy improvement, and the consumer payback period, the latter generally on the order of
about 1-2 years. The best payback for a midsize car hydraulic hybrid technology package in this
alternative cost scenario, involving a conventional gasoline engine with full hydraulic hybrid
drivetrain and engine-off strategy, is 6.0 years, compared to a payback of 4.2 years with the
hydraulic hybrid cost assumptions in Section 6.
It now appears that future hydraulic hybrid designs will likely evolve toward operating pressures
of 7000 pounds per square inch (psi). The designs described in Section 3 could accommodate
pressures of 7000 psi, but were sized based on a maximum operating pressure of 5000 psi in
order to be conservative. Operating at 7000 psi would reduce the size and cost of key hydraulic
components (pump/motors and accumulators) on the order of 30 percent. In view of this likely
evolution, as well as the likelihood of other unforeseen cost reductions driven by a sustained
future market, EPA believes that the alternative cost scenario suggested by the reviewer (based
Jan 2004
Progress Report on Clean and Efficient Automotive Technologies
page O-6
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APPENDIX O
on annual component production volumes of 500,000) should be viewed as an upper bound with
a high likelihood that sustained costs would be lower.
5. Two reviewers pointed out that there might be additional consumer operating costs associated
with maintenance of hydraulic components such as pump/motors and accumulators. EPA
recognizes this as a possibility, but there is not yet information on which to base such a
projection, and any such maintenance costs are likely to be small relative to the primary cost
factors of component cost, fuel savings, and brake maintenance savings. Accordingly, no
changes were made in this regard. One reviewer also suggested that noise isolation and
advanced braking designs might be necessary for hydraulic hybrids, which could add cost. EPA
believes that these modifications may or may not be necessary, and because of this uncertainty
EPA has not modified the cost analysis.
6. Two reviewers asked for more detail about the diesel aftertreatment cost projections, and one
reviewer stated that: "Aftertreatment costs are expected to be significantly higher than EPA
estimate, due to addition of DPF and NOx treatment with large volumes and precious metal
requirements." EPA has retained the estimate of diesel aftertreatment costs in the draft report.
There is a major industry effort underway to develop viable and cost-effective diesel emission
control systems. There is great uncertainty as to the ultimate design and cost of such systems,
and EPA believes its original estimates are still the best available at this time. EPA will refine its
diesel aftertreatment cost estimates as more information becomes available.
7. One reviewer was skeptical of the use of a 1.26 retail price equivalent mark-up factor, and
cited the use of a 1.4 factor in the National Academy of Sciences report on CAFE published in
January 2002. The Office of Management and Budget has endorsed the use of the 1.26 mark-up
factor in EPA motor vehicle regulatory development, and EPA considers it important to be
consistent in the application of retail mark-up factors.
8. One commenter recommended the addition of a "$ per % fuel economy improvement" metric
to the summary tables in the report. EPA has modified tables ES-1 and ES-2 to include this
metric.
9. One reviewer "suggested that EPA consider providing copies of the modeling and simulations
developed to aid in the technology transfer to industry." In response to this comment, EPA is
prepared to share the models and simulations with outside parties that request them.
While these were the more important and/or comprehensive comments, many other helpful
suggestions led to more minor improvements in the progress report. EPA appreciates the time
and effort invested by all of the reviewers of the draft report, and the progress report is clearly
improved because of the comments.
Jan 2004 Progress Report on Clean and Efficient Automotive Technologies page O-7
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