EPA-AA-SDSB-80-11
Technical Report
Electronic Engine Controls - Availability,
Durability, and Fuel Economy Effects on 1983
and Later Model Year Light-Duty Trucks
by
Thomas Nugent
Zachary Diatchun
Timothy Cox
June 1980
NOTICE
Technical Reports do not necessarily represent final EPA decisions
or positions. They are intended to present technical analysis of
Issues using data which are currently available. The purpose in
the release of such reports is to facilitate the exchange of
technical information and to inform the public of technical devel-
opments which may form the basis for a final EPA decision, position
or regulatory action.
Standards Development and Support Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Office of Air, Noise and Radiation
U.S. Environmental Protection Agency
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I. Introduction
The application of microprocessor technology to optimize the
functions of the internal combustion engine is underway. Passenger
car model years 1980 and 1981 have seen the widespread introduction
of electronic engine controls of varying degrees of complexity.
These controls hold the promise of lowering engine emissions and
raising engine fuel economy through the optimization of the com-
bustion process at all engine operational conditions.
This paper examines the potential of this technology for use
in the future light-duty truck fleet. The implications of this
technology on fleet fuel economy, in conjunction with the more
stringent emission standards in 1983, will be examined along with
projections as to the future availability and durability of these
microprocessors and their associated engine sensors.
II. Availability
Three factors are identifiable in analyzing the availability
of electronic engine controls for 1983 light-duty truck application
to meet emission and fuel economy requirements. The first factor
concerns the availability of sufficient technology to implement
such controls. Secondly, production limitations are an important
factor. Finally, costs of electronic engine controls using the
selected technology may be prohibitive.
The use of electronics in automotive applications, especially
iri the area of" engine controls, is one of the fastest growing areas
of electronic development and has been stimulated at an accelerated
pace by emission and fuel economy requirements. Electronic engine
controls first appeared in the early 1970's with the introduction
of ignition modules and increased in complexity and application to
controlling spark timing in the late 1970's. Chrysler's "Lean Burn
engine," General Motors' "MISAR" system, and Ford's "EEC-1" are all
examples of modules that controlled spark timing. Although no
statute exists requiring the use of electronic engine controls,
future emission and fuel economy requirements dictate that further
increases in electronic control of the powertrain will accompany
downsizing, aerodynamic changes, and improvements in catalyst
technology to meet fuel economy and emission requirements of the
1980's.
The initial development effort in the early seventies used
analog circuitry. This development technique illustrated that
electronics could provide a substantially more accurate engine
control system but would not improve fuel economy and emission
levels unless a more advanced methodology was developed. With the
advent of microprocessors and large scale integration (LSI) tech-
niques developed in the late 1970's, the automotive world became a
prime candidate to reap the benefits of what many social observers
refer to as the second industrial revolution. This advanced LSI
technology brings about an unprecedented level of functional
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complexity and intelligence for engine control systems and replaces
many previous mechanical and electromechanical solutions.
Parallel to the development of LSI techniques for engine
control applications, sensor development became the pacing factor
for using microprocessor based engine controls. The more important
sensed parameters that are used in 1980 model year light-duty
vehicle applications are:ll/
- Crankshaft angle position. This indexes ignition timing for
spark advance control and injection timing for electronic fuel
injection systems. There are five current technologies commonly
used to sense this parameter: magnetic reluctance, Hall-effect,
Weigand-effeet, optical, and variable-inductance.
- Pressure. This includes manifold absolute pressure (MAP),
manifold vacuum, and ambient absolute pressure (AAP). MAP param-
eters are used with speed/density fuel control systems; mani-
fold vacuum is used for ignition control and load sensing; AAP
parameters are used for exhaust-gas-recirculation (EGR) flow
correction and for altitude compensation. Technologies in pro-
duction include aneroid/ LVDT, diaphragm/silicon strain gage,
capacitive, surface wave diaphragm, aneroid/linear inductor, and
metal diaphragm/ semiconductor strain gauge.
- Coolant temperature. These are now mature components with
thermistors and wire-wound resistive elements used for cold start
emission requirements.
- Oxygen partial pressure is monitored in three-way catalyst
systems. Two sensors are of interest; zirconia oxygen sensor and
the titania oxygen sensor.
- Throttle position is monitored for engine power command and
idle shut-off on coastdown. As in the case of coolant temperature,
throttle position technology is mature with plastic and ceramic
element potentiometers dominating the market.
With' the assistance of the LSI revolution and the neces-
sary peripheral sensor developments, electronic engine controls
have increased. In light-duty vehicle (LDV) applications, General
Motors plans to use a three-way catalyst system with feedback
•carburetor for all 1981 LDV applications; Ford is also contem-
plating full usage of a similar system (EEC III) for full LDV
application in 1983.
The usage of such complex systems (three-way catalysts and
feedback carburetors) is not necessary to meet emission standards
for 1983 LDTs since the equivalently stringent 1980 LDT California
emission standards are met without any electronic engine controls
or three-way catalyst systems. The 1980 California standards are
more stringent than the 1983 Federal standards (see Fuel Economy
section). A simple spark advance/EGR electronic engine control
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4
system, developed in the late 1970's, should be all that is neces-
sary to meet emission and fuel economy standards.
Therefore, regarding technological availability for 1983 LOT
electronic engine control application, the question is no longer
"can it be done," but rather "when, what quantity, and for what
price."
Another area affecting availability of electronic engine
controls for 1983 LDT application is production limitations.
Total LDT electronic engine control application could increase
production volume up to 33 percent over LDV applications. Tooling,
production leadtime, and facilities are all limiting factors
in production. Any design changes necessary to meet 1983 LDT
requirements would principally involve a rewrite of the micropro-
cessor software in already existing systems. An industry stan-
dard currently held by microprocessor manufacturers is 26 weeks
for complete microprocessor development. Discussions with Motor-
ola, a manufacturer of electronic engine controls and associated
sensors, indicated that a production volume increase of about
3 times would take 22-30 weeks to implement and would be paralleled
by any necessary microprocessor software changes. Additionally,
Motorola acknowledged that such a production volume increase would
require an accelerated program, but by no means an impossible
program, for the 1983 model year implementation. Ford engineering
also made comments consistent with Motorola on the production
availability of electronic engine controls, i.e., an accelerated
program would be necessary and feasible.
The last factor which may limit electronic engine control
availability is prohibitive costs. Surveys have been done on the
percentual share of manufacturing costs of LDV for electronics in
the next decade. Figure 1 indicates that a 4 percent increase in
percentual share cost in 1983 is expected compared to the uncon-
trolled LDV emission baseline (pre!968) electrical system share
cost of 8 percent. A 1-2 percent deletion from the 4 percent
incremental level is justified if only electronic engine controls
are considered. The 1-2 percent deletion is attributable to
increased electronic technology applications to instrument panels
and driver convenience devices such as clocks, air conditioning
controls, and diagnostic warning systems.12/ A further, detailed
cost analysis has been developed and presented on the anticipated
application of electronic engine controls for 1983 LDTs in the
Regulatory Analysis and Environmental Impact of Final Emission
Regulations for 1983 and Later Model Year Light-Duty Trucks.1Q/
The net increase in retail cost is anticipated to be $95 (1980
dollars), and is similar in percentual share cost to LDVs.
While there are incremental costs associated with the applica-
tion of electronic engine controls for 1983 LDTs, cost would not be.
a limiting factor affecting the availability of such controls.
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III. Durability
There have been three generally accepted techniques used in
predicting the durability of any system used in automotive appli-
cation :_13/
a. Accumulated data from actual field experience.
b. Analytical techniques.
c. Accelerated life testing.
The first method applied to electronic engine controls is
currently not extensively available because of the newness and
rapid evolution of LSI technology applied to the automotive field;
1983 electronic engine control systems are being developed now in
1980. Analytic techniques require a mature data base; life testing
usually produces a generic failure rate and relies heavily upon
extrapolation. Both of these methods, b and c, would have to be
used in establishing confidence in an electronic engine control
system for 1983 LDT application.
A reasonable durability confidence level may be established
for LSI techniques used in electronic engine controls. The latest
circuits contain up to 100,000 transistors in memory arrays, or up
to 50,000 transistors in random logic. Even with this semicon-
ductor complexity, the actual reliability has increased. Figure 2
illustrates the failure rate per function versus time or device
complexity.
Factors affecting the increase in durability are three-
fold. First, a system using LSI techniques results in a decrease
in the number of peripheral electronic components. Second,
as device complexity increases, the number of external LSI chip
interconnections, such as chip lead bonding, is significantly
reduced. Chip lead bonding has been identified by the industry
as one of the principal causes of failure when exposed to the
automotive environmental factors of temperature extremes and
humidity,* Third, and perhaps most importantly, significant ad-
vances in device manufacturing techniques and knowledge of device
mechanisms has facilitated production of LSI devices which improve
failure resistance when exposed to extremes in environmental
' conditions.
There have been identified, however, some problems unique to
LSI technology when applied to the automotive field as compared to
discrete devices. Discrete devices are reasonably immune to
effects of power supply variation and little or no protection has
been taken in the past against control transients, steady-state
noise, and voltage regulation. Automotive environments contain
complex signals under each of these areas including load dump
transients, electromagnetic interference, alternator field delay
transients, and accessory noise.
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6
The nature of LSI failure rates may be further discussed by
using two partitions: intrinsic and extrinsic. Intrinsic failure
rates are associated with manufacturing defects such as masking
areas» process contamination, and passivation defects. These
defects dominate the failure rate in applications where the en-
vironment is controlled, e.g. computers. Extrinsic failures are
caused by environmental factors. As environmental severity in-
creases, the'contribution of the extrinsic failure rate increases.
Figure 3 illustrates the influence of environmental severity on
device failure rates.14/
Sensors used for engine controls have been identified as
the limiting factors in durability, especially electro-mechanical
devices. Even though guidelines have been set on the specifica-
tion and testing on some of the sensors,15J the most crucial factor
in establishing confidence in a 100,000 mile durability factor
for LDTs is actual in-use experience, which is currently not
available at mileages up to 100,000. However, a reasonable degree
of durability confidence may be applied to the sensors that will
potentially be used on 1983 LDTs to meet emission and fuel economy
requirements. Such sensors are the crankshaft position and the
manifold vacuum sensor. These particular sensors have a high
durability potential as they are either non-mechanical, use solid
state technology, have a long aerospace history, and exhibit no
severe environmental deterioration problems, as is the case of the
oxygen sensor used with three-way catalyst systems.
... Concluding, both the electronics and sensors that may be used
on 1983 LDTs have a high durability potential because of increases
in the development of large scale integration and the already
secure, sensor development.
IV. Fue1 Economy
Manufacturers' comments to the National Highway Traffic Safety
Administration's (NHTSA) light truck fuel economy proposed stan-
dards for 1982 through 1985 model years, and to EPA's Light-Duty
Truck (LOT) proposed emission regulations for 1983 are consistent.
According^, to the manufacturers, the 1983 and 1985 emission stan-
dards will result in a fuel economy penalty ranging from 3-14
percent. The EPA staff's intention in this report is to address
manufacturers' comments concerning the fuel economy penalty as-
sociated only with the 1983 emission standards.
Most manufacturers further agree through passenger car
research that Electronic Engine Controls (EEC), more specifi-
cally fully interactive EEC systems, have shown promise in com-
bating the loss of fuel economy as demonstrated by application
of the more stringent California standards to passenger vehi-
cles. Manufacturers further claimed, however, that such systems
are not generally planned to be used to achieve 1983-1985 LOT
standards due to what the manufacturers vifew as their high variable
cost.
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One manufacturer indicated that while a system of this type
was not necessary to attain 1983 emission standards, it could be
justified if cost effective with regard to fuel economy. The same
manufacturer referred to computer simulations with EEC that re-
sulted in a fuel economy benefit of at least 2 percent.
On the other hand, additional'manufacturers' research yielded
no fuel economy benefit with EEC with or without three-way cata-
lysts, and then concluded that the fuel economy penalty could not
be offset, and also dismissed the use of EEC for 1983 due to
leadtime requirements.
Finally, when questioned in Public Hearings before EPA about
the use of electronic controls in future product lines, the indus-
try refused to comment on the grounds that such information was
"proprietary." Given the widespread use of EECs in the LDV fleet
and given the constantly growing amount of published research on
EECs, this is highly suggestive that the research and development
programs heeded to incorporate EECs into the LDT fleet are already
underway.
These inconsistencies in the manufacturers' comments indicate
the need for a more critical review of current EEC technology with
respect to fuel economy, emission standards, and the future LDT
fleet.
Industry projections for fuel economy impact arise from
anticipated use of current technology at emission levels near the
1980 California standards. The magnitude of this Federal to
California fleet fuel economy penalty was estimated in Reference
1 to be approximately 4.0 percent, as determined from EPA certi-
fication tests on an average vehicle-by-vehicle basis. A conserva-
tive estimate of 1983 production mix for different engine sizes and
corrections for relative stringencies of standards also entered
into the derivation of the average penalty.
A separate source for evaluating the effect of California
emission standards upon LDT fuel economy is a recent SAE paper
published^by EPA personnel.2/ Data from that report is reproduced
in Table 1. The average penalty for each manufacturer is broken
down in Table 2. Note that the average sales-weighted fuel economy
impact per manufacturer of the California emission standards was
found to be a loss of 4.2 percent. (This is comparable to the
overall 5.2 percent loss derived by the EPA staff in Reference
1, before adjustments were made for future engine mix and for the
relative stringencies of 1980 California and 1983 Federal emission
standards.) Note also the significant impact of the changing
marketplace; an increase in sales of products by manufacturers of
more fuel efficient vehicles in California has resulted in a net
improvement in overall fleet fuel economy of 6.5 percent relative
fo the Federal fleet! Significant increases in fleet fuel economy
and simultaneous reductions in emissions have occurred. This is
not to say that market mix negates the effects of tighter emission
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3
standards. It is in the context of an anticipated 4.0 percent
loss* in average engine fuel efficiency using current technology
that the fuel economy effects of future technology, electronic
engine controls in particular, will be evaluated. (This change in
market mix to more fuel-efficient vehicles and its overall effect
on fleet mpg should not go unnoticed, however.)
Given the availability of electronic engine controls, EPA
anticipates their incorporation into the LDT fleet to achieve
compliance with increasingly stringent emission and fuel econ-
omy standards. This judgement is based upon the documented
potential for engine optimization attributable to EECs, and
their already widespread use in the light-duty vehicle (LDV)
fleet.
The level of complexity of electronic controls can vary.
Parameters controllable by electronics include fuel/air ratio,
spark advance, EGR rate, idle speed, auxiliary air injection,
torque converter clutch, fuel injection profile, and ignition
voltage. Electronic controls permit infinitely variable cali-
bration settings for each parameter and for changes in engine
operating demands - including idle, acceleration, deceleration,
cruising, and transient temperature (warm-up) effects. Cali-
brations and response times of each feedback control loop can
be set to optimize fuel economy and driveability at any level of
emissions. A method of engine parameter mapping and control
algorithm generation is presented by Auiler, et al.J>/ A complete
description of a comprehensive electronic control system is given
by Grimm, et al.6/
The degree of complexity required for 1983 LDTs to attain
emission standards while incurring no net fuel economy penalty
was judged previously to be less than that of a comprehensive
system, i.e. electronic control of only a few parameters will be
sufficient. Most likely controlled will be spark advance and EGR
rate. The option still exists for more complex systems to be
introduced at the manufacturer's discretion. With forthcoming NOx
reductions in 1985, manufacturers may choose to phase in com-
prehensive control systems because of varying leadtimes for
microprocessor programming and engine optimization - see the
conclusions in Reference 4. We do not judge these leadtimes to be
prohibitive to introducing less complex, less costly EEC's in 1983,
however, due to the previous design experience acquired with
light-duty vehicles.
Several reports have outlined the fuel economy and emission
reduction potential of electronic spark advance (ESA), and of
comprehensive EECs including ESA. Schwarz, in a report to the
Institute of Electrical Engineers^/, reported that at a given
emission level, use of a digital ESA system produced a 8-11
percent fuel economy improvement over a mechnical system in a
As derived in Reference 1.
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four cylinder passenger car engine. Evernham, et al, reported
in 1978 9/ that the first microprocessor unit installed on a
production passenger car (GM MISAR system on the 1977 Oldsmobile
Toronado), a simple electronic spark advance system, improved fuel
economy by 1.2 mpg (9 percent)* over the mechanical system. It is
difficult to understand the industry's claims that technology first
applied in 1977 cannot be applied to LDTs in 1983 to preclude a
fuel economy penalty, which will at most be a fleetwide 4.0
percent using current LDT technology, while technology introduced
six years prior to 1983 on passenger cars produced fuel economy
improvements of 8-11 percent.
Comprehensive EECs, although not anticipated to .be widely
used in 1983 LDT's, nevertheless incorporate ESA, and evaluation of
a comprehensive system> fuel economy potential can indicate to some
degree a range of ESA's potential. IkeuraS/ reported that the
comprehensive system developed by Nissan and currently marketed
extensively in Japan produced an overall improvement in fuel
economy of 10 percent. (The Nissan system controls fuel injection,
spark advance, EGR rate, and idle air flow). Some fraction of this
improvement must be attributable to ESA and EGR control, and its
certainly reasonable to conclude that at least 4.0 percent of the
overall 10 percent is attributable to ESA and EGR control.
Lockhart4/ reported different magnitudes of improvements, but
which are highly informative nevertheless. Table 3 lists the
emission levels and fuel economy improvements obtained in a GM
prototype fuel economy vehicle equipped with, among other tech-
nologies, a GM EPEC (Electronic Programmed Engine Control.) While
simultaneously reducing emissions from 1978 to 1981 levels, an
overall fuel economy benefit of 12.5 percent was achieved, of which
3.5 percent was attributable to the comprehensive EPEC (which
controlled fuel injection, spark advance, idle air, and EGR.)
Emission reductions were reported to decrease net fuel economy by
2.5 percent. In extrapolating these results to future LDTs, it is
understood that a comprehensive system is not anticipated for 1983,
but also note that the relative degree of emission reductions
required for 1983 LDTs are far less than that seen by passenger
cars frony 1978 to 1983 (although differences in inertia weights
certainly affect attainable emission levels.) Therefore, although
a comprehensive EEC is not anticipated, the emission reductions are
not quite so drastic (most importantly for NOx) as achieved in
Reference 4. The fuel economy impacts of lower LDT standards and
the use of ESA and electronic EGR controls are judged comparable in
magnitude and opposite in sign, i.e. no net fuel economy penalty is
expected. In fact, based upon data presented in the earlier
reference, it is conceivable that the fuel economy benefits of
the expected EECs may be larger than those penalties associated
with the 1983 emission reductions.
* EPA combined fuel economy ratings for the 1977 Toronado was 15
mpg. Presuming 15 mpg represents 1.2 mpg more than 13.8 rapg, the
ESA resulted in a 9 percent gain.
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10
In summary, the 1983 emission reductions are not drastic and
are attainable with' today's technology. Today's electronic control
technology as applied to light-duty vehicles will permit no net
fuel economy penalty to be experienced as a result of these emis-
sion standards. Industry claims of fuel economy penalties are not
consistent with the cost-effective* technological options avail-
able. Looking at the engine alone, there is no reason to presume
that fuel economy effects attributable to the 1983 standards will
be negative. We believe it is a conservative judgement based upon
the published data that no net fuel economy loss will occur.
See Reference 1, Chapter F; Reference 10, Chapter 5.
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References
I/ "Summary and Analysis of Comments on the Notice of Proposed
~ Rulemaking for Gaseous Emission Regulations for 1983 and Later
Model Year Light-Duty Trucks," U.S. EPA, May 1980.
2J "Passenger Car and Light Truck Fuel Economy Trends Through
~ 1980," by J.D. Murrell, et al, SAE Paper No. 800853.
3/ "Microprocessor Control Brings About Better Fuel Economy with
~ Good Driveability," by K. I. Ikeura, et al, SAE Paper No.
800056.
4/ "A Fuel Economy Development Vehicle with Electronic Programmed
~ Engine Controls (EPEC)," by Bruce D. Lockhart, SAE Paper No.
790231.
5/ "Optimization of Automotive Engine Calibration for Better Fuel
Economy - Methods and Applications," by J. Auiler, et al, SAE
Paper No. 770076.
6/ "GM Micro-Computer Engine Control System," by R. Grimm, et al,
SAE Paper No. 800053.
7/ "Chrysler Microprocessor Spark Advance Control," by J.
Lappington and L. Caron, SAE Paper No. 780117.
Bf "Features and Facilities of a Digital Electronic Spark Advance
" System and its Advantages Compared with Mechanical Systems,"
by H. Schwarz from Automotive Electronics, IEE Conference
Publication No. 181, November 1979.
_9_/ "MISAR - The Microprocessor Controlled Ignition System," by T.
Evernham and D. Guetershlok. SAE Paper No. 780666. :
10/ "Regulatory Analysis and Environmental Impact of Final Emis-
sion Regulations for 1983 and Later Model Year Light-Duty
Trucks, U.S. EPA, May 1980. ^
./
11 / "Automotive Engine Control Sensors '80," by William G. Wolben,
SAE Paper No. 800121.
,12/ "Current Status of Automobile Electronic in Europe," by K.
Ehlers, from Automotive Electronics, IEE Conference Publica-
tion No. 181, November 1979.
13/ "Electronic Reliability Issues Relating to Automotive Pro-
duct," by J.G. Rivard, SAE Paper No. 780833.
_14/ "The Automobile and the Microcomputer Revolution — Solving
the Reliability Problem," Automotive Electronics, IEE Con-
ference Publication No. 181, November 1979.
15/ "Guidelines for Establishing Specifications and Test Methods
for Automotive Sensors," by R.K. Frank, SAE Paper No. 800022.
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Table 1 2/
Percent Difference in 1980 California Truck MPG Due to:
* - T j i i. • •• -ir _ . . .
1980
49-States
Manufacturer Truck SWMPG
American Motors
Chrysler Corp.
Ford Motor Co.
General Motors
Nissan (Datsun)
Toyo Kogyo
(Mazda)
Toyota
Volkswagen
Fuji
(Subaru)
16.6
17.3
16.8
16.6
25.3
30.4
20.5
24.9
26.3
System
Optimization
-5.3
-5.9
-5.0
-5.1
-5.1
-4.7
-6.3
-1.2
-6.7
l :
Transmission
Mix Shifts
0.3
-0.2
-0.8 '
0.1
0.0
0.0
-0.1
0.0
0.0
Engine
Mix Shifts
-1.3
-10.8
-1.8
-0.9
0.0
0.0
0.1
0.0
0.0
Weight
Mix Shifts
-4.3
16.0
7.5
3.9
-0.2
-0.1
3.4
-1.1
0.0
All Changes
Combined
-10.2
-2.8
-0.8
-2.2
-5.3
-4.8
-3.2
-2.3
-6.7
1980
California
Truck SWMPG
14.9
16.8
16.7
16.2
24.0
29.0
i— '
NJ
19.9
24.3
24.6
Fleet
17.0
-5.3
0.0
-1.9
14.6
6.5
18.1
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13
Table 2*
Relative Fuel Economy by LPT Manufacturer
Manufacturer
AMC
Chrysler
Ford
GM
Nissan
Toyo Kogyo
Toyota
VW
Fuji
Fleet
Average Loss
Federal SWMPG
16.6
17.3
16.8
16.6
25 . 3
30.4
20.5
24.9
26.3
17.0
per Manufacturer (%):
California SWMPG
14.9
16.8
16.7
16.2
24.0
29.0
19.9
24.3
24.6
18.1
-4.2
% Less
-10.2
-2.9
-0.6
-2.4
-5.1
-4.6
-2.9
-2.4
-6.7
+6.5
"
* From Table 1
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14
Table 3 4/
Emission and Fuel Economy Results
HC CO NOx
1978 LDV standards: 1.5 15 2.0
1981 LDV standards: .41 3.4 1.0
Percent reduction: 73% 77% 50%
1980 LDT standards: 1.7 18.0 2.3
1983 LDT standards: .76* 9.1* 2.0*
Percent reduction: 50% 49% 13%
% Fuel Economy Improvements:
All efficient technologies: +15%
Calibration to 1981 LDV -2.5%
emission standards:
Overall improvement of 1978 +12.5%
base case:
Improvement attributable +3.5%
to full.EPEC:
* A revised definition of useful life and stricter assembly line
testing procedures essentially increase the stringency of the 1983
LDT standards. The increased stringency, as derived on page 69 of
Reference 1, has been taken into account by lowering the actual
standards by the amount by which stringency is increased.
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15
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1970
75
80
85
Share of cost of electric & electronic components
in total vehicle cost
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