EPA-AA-SDSB-84-1
Technical Report
Heavy-Duty Vehicle Emission
Conversion Factors
1962-1997
By
Mahlon C. Smith, IV
August 1984
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
developments which may form the basis for a final hPA
decision/ position or regulatory action.
Standards Development and Support Branch
Emission Control Technology Division
Office of Mobile Sources
Office of Air and Radiation
U. S. bnvironmental Protection Agency
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I. Introduction
MOBILES is a computer program that generates in-use
emission factors by calendar year, ambient temperature and
driving situation in units of grams per mile (g/mi) for all
vehicle classes, which are then used to determine emissions
inventories in various localities. Because urban areas are
modelled almost exclusively, urban emission factors are desired
and generated. Because heavy-duty engine testing provides
emissions in terms of grams per brake horsepower-hour
(g/BHP-hr), brake horsepower-hour per mile (BHP-hr/mi) emission
conversion factors are needed to convert the brake-specific
emission levels into the necessary mile-specific (g/mi) units,
as illustrated below:
Emission Factor = Emission .Test Data x
Emission Conversion Factor
g = g x BHP-hr
mi BHP-hr mi
This technical report outlines the methodology used to
determine these conversion factors, as well as providing the
specific conversion factors for heavy-duty gasoline and diesel
engines, for the model years 1962 through 1997 (see Tables 1
and 2) .
The BHP-hr/mi conversion factors were calculated from
brake-specific fuel consumption (BSFC), fuel density, and fuel
economy, (all of which can be measured) because it is difficult
to measure BHP-hr/mi directly. The eauation used was:
heavy-duty vehicle conversion factor = fuel density/(BSFC X
fuel economy), with corresponding units of BHP-hr/mi = (lb/gal)/
[(lb/BHP-hrj X (mi/gal)].
The emission conversion factors were first calculated by
specific gross vehicle weight ~(GVW) class for both gasoline-
and diesel-powered vehicles, as both BSFC and fuel economy vary
with gross vehicle weight and fuel type. Diesel and gasoline
fleet-average conversion factors were then calculated using the
appropriate vehicle miles traveled (VMT) weighting of the
class-specific conversion factors. Gasoline and diesel
fleet-average conversion factors were derived separately
because MOBILES treats them separately.
Estimates of historic BSFC and fuel economy fiaures are
available -for vehicles of model year 1977 and earlier. Thus,
historic class-specific conversion factors may be easily
calculated using the equation given above. Future conversion
factors will not be affected by changes in BSFC, as any
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Table 1
Pre-1978 Fleet-Average Emission
Conversion Factors (BHP-hr/mi)
Year
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
Gasoline
1.29
1.31
1.32
1.33
1.35
1.36
1.37
1.37
1.37
1.37
1.37
1.34
.1.31
1.28
1.20
1.12
Diesel
2.74
2*74
2.73
2.72
2.76
2.82
2.88
2.94
3.00
3.08
3.15
3.19
3.23
3.27
3.23
3.19
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Table 2
Post-1977 Fleet-Average Emission
Conversion Factors (BHP-hr/mi)
Year
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
'1993
1994
1995
1996
1997
Gasoline
1.08
1.05
1.01
0.98
0.95
0.95
0.95
0.96
0.97
0.97
0.97
0.96
0.96
0.96
0.95
0.94
0.94
0.93
0.92
0.92
Diesel
3.07
2.95
2.84
2.72
2.60
2.56
2.51
2.47
2.43
2.38
2.38
2.37
2.36
2.35
2.34
2.33
2.33
2.32
2.31
2.31
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decrease in BSFC will be cancelled out by a corresponding
increase in fuel economy. As fuel density is assumed to be
constant, the only factors affecting future heavy-duty vehicle
conversion factors are future non-engine-related fuel economy
improvements. Future class-specific conversion factors are,
thus, estimated by reducing the 1977 conversion factors in
proportion to the projected increase in fuel economy due to
non-engine-related factors. For. this reason, historic and
future conversion factors are calculated separately; the former
using the above equation, and the latter using projected
non-engine-related fuel economy improvements applied to the
1977 conversion factors.
This report beains with a description of the fuel
densities, BSFCs, and fuel economies used to calculate the
historic class-specific conversion factors. Following this
discussion, the VMT-weighting methodology used to obtain the
fleet-average conversion factors is presented and each factor
used in the VMT weighting process is described. Future
non-engine-related fuel economy improvements are then analyzed
and their application to historic class-specific conversion
factors described. A discussion of the VMT-weighting factors
for future fleet-average conversion factors concludes the
report.
A study was conducted by Energy and' Environmental
Analysis [1] (EEA) for the Motor Vehicle Manufacturers
Association (MVMA) to estimate historic and future emission
conversion factors as defined in this report. This study
provides a background for estimating these conversion factors
and is referenced throughout this report.
II. Historic Class-Specific Conversion Factors
Historic class-specific conversion factors were calculated
using three basic parameters: fuel density, brake specific fuel
consumption, and fuel economy, as detailed above. These three
parameters are detailed in the subsequent paragraphs.
A. Fuel Density
The gasoline and diesel fuel densities used in the
calculation of historic conversion factors were 6.16 and 7.07
pounds (Ibs.) per gallon, respectively. These values were used
by EEAfl] in their calculations and result from a conceptually
indirect methodology, but one using readily available figures.
They divided the number of .grams of carbon per gallon of fuel
by the ratio of carbon mass to total fuel mass and then
converted this density from grams per gallon to pounds per
gallon. The values used for grams of carbon per gram of fuel
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(2421 for gasoline, 2778 for diesel fuel) and the carbon/total
mass ratio (.866) were taken from the Code of Federal
Regulations. [2] The resulting fuel densities are within
1 percent of the specific gravities of commercial gasoline and
diesel fuel, as surveyed by MVMA[3,4] (.7444 for gasoline and
.8572 for diesel) and were, thus, accepted for use in MOBILES.
B. Brake-Specific Fuel Consumption
The class-specific gasoline and diesel BSFCs ("BSFCG" and
"BSFCD," respectively, in Table A-l) from the EEA report[1] are
similar to those from EPA engine dynamometer tests (see
Table 3). Thus, they were -accepted for use here in calculating
historic class-specific conversion factors. The EEA report did
not address trarisit buses. Since it is desirable to include
the effect of such vehicles on the fleet-average diesel
conversion factor, an historic BSFC for this class of vehicles
had to be derived. As pre-1978 bus engines were almost
entirely 2-stroke naturally-aspirated engines, they were
estimated to be roughly 4-5 percent less efficient than Class
V-VII engines (0.46 Ib/BHP-hr) which are a mixture of
naturally-aspirated and turbocharged 4-stroke engines. The
resulting bus engine BSFC of 0.48 Ib/BHP-hr was generally
confirmed in a study by Southwest Research Institute,[6] where
the BSFC of an 8V-71 bus engine was found to be 0.47
Ib/BHP-hr. The MOBILE3 BSFCs are shown in Table A-2.
C. Fuel Economy
All fuel economies (except those form Class lib vehicles
and buses) were taken directly from the 1977 Truck In-use
Survey (TIUS) [2] as detailed in the EEA report. [1] The fuel
econommy for all Class II vehicles was reported by EEA.
However, only Class lib fuel economy is pertinent to heavy-duty
vehicle emissions, as Class Ila vehicles are treated as
light-duty trucks in MOBILES. The Class II fuel economy of
!.11.12 mpg (gasoline) from the 1977 TIUS is a weighted average
of Class Ila and Class lib fuel economies. EEA[8] supplied
information indicating that Class lib sales make up 10.7
percent of Class II sales. This figure is very similar to that
estimated by a previous EPA study.[9] Using an estimate that
Class lib fuel economy is 10 percent less than Class Ila fuel
economy yields a Class lib fuel economy of 10.12 mpg, this was
taken to be constant for all years prior to 1978 as the TIUS
data indicated Class II fuel economy was constant. [1] The
transit bus fuel economy of 3.68 miles per gallon was estimated
using data from the 1981 Transit Fact Book. [10] EEA fuel
economies are shown in Table A-l, which uses "MPGG" for
gasoline and "MPGD" for diesel fuel economies, and the MOBILES
fuel economies are shown in Table A-2.
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Table 3
Brake-Specific Fuel Consumption (Ib/BHP-hr)
Diesels
Class VI
Average of 4 Engines:
BSFC = 0.4645 EEA Estimate:
std. dev. = 0.21
Class VIII
0.46
Average of 7 Engines: BSFC = 0.440 EEA Estimate: 0.43
std. dev. = .031
Gasoline
Average of 2 Engines: BSFC = .69
delta = .029
EEA Estimate: 0.70
Taken from Reference 5.
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The TIUS fuel economies are national fuel economies (i.e.,
the result of a combination of rural and urban driving).
Different fuel economy data from tests made by the Southwest
Research Institute (SwRl)[11] over the EPA heavy-duty chassis
dynamometer cycle are given in Table 4. Rural fuel economy was
assumed to be represented by the Los Angeles freeway portion of
the test, with urban fuel economy being that over the entire
urban (composite) cycle. This data shows that the average
composite (urban) fuel economy is 17 percent lower than an
estimate of the average Los Angeles freeway (rural) fuel
economy. This indicates that perhaps the TIUS national fuel
economies should be revised downward to better represent urban
fuel economies. However, data from a July 1976 report by Jack
Faucett Associates[12] (see Table 5) show lower loads in urban
driving than during over-the-road driving, resulting in a 5-10
percent increase in urban fuel economy over rural fuel
economy. Combining the fuel economy effect of the lower urban
load benefit and the national/urban differences based on SwRI
data results in rural fuel economy still being 7-12 percent
greater than urban fuel economy.
Track test data supplied by GM[12] (see Table 6) over SAE
truck driving cycles contradicts this, showing urban fuel
economy to be equal to or greater than rural fuel economy, if,
as GM did, it is assumed that urban trucks are lightly loaded
and over-the-road trucks are full loaded. The 1977 TIUS (see
Figures 1 and 2) confirms this relationship between urban and
over-the-road (intercity) fuel economy.
Upon consideration of the TIUS data, and acknowledging
that: 1) the SwRI data is limited, and 2) the representative-
ness of the LA freeway portion of the EPA cycle as rural
driving is uncertain, the TIUS national fuel economies were
taken as being representative of urban fuel economy as well.
Further investigation into this area is necessary, and it may
be appropriate to adjust national fuel economies in the future
, to represent urban fuel economies if additional data confirm
the need for such adjustment.
In summary, historic class-specific conversion factors
were based on: fuel densities from EEA,[1] BSFCs from EEA,[1]
and fuel economies from the 1977 TIUS,[7] with Class II
adjusted to represent Class lib. The only exception was for
transit buses, where the BSFC was based on dynamometer testing
and the fuel economy was based on UMTA data. These historic
gasoline and diesel class-specific conversion factors ("GCF"
and "DCF", respectively) are listed in Table A-3. The
class-specific conversion factors must then be VMT weighted to
determine historic fleet-average conversion factors, which is
described below.
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Table 4
Engine Model
1982
1979
1979
1979
Over a
Cummins
350
Cummins
NTC290
Ford 370
IHC 345
11 Average
Test '
Type
CS
HS
CS
HS
CS
HS •
CS
HS
Fuel
L.A
Cons. Fuel Cons.
. FWY Composite
(L/lOOkm) (L/lOOkm)
44
42
51
49
43
44
52
50
.40
.92
.04
.72
.36
.08
.67
.47
Urban/Highway Fuel
54.
51.
63.
59.
53.
57.
62.
56.
59
26
51
12
86
94
64
61
Economy
»
- Urban/Hwy
FE Ratio
.813
.837
.804
.841
.805
.761
.841
.891
Ratio
Wtd. -
FE Ratio
.834
.836
.783
.884
.834
Taken from Reference 11.
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Table 5
Average Vehicle Load (tons)
Truck Class Local
Size Gasoline
Class
Class
Class
Class
Class
Class
Class
Class
Total
1
2
3
4
5
6
7
8
.24
.45
.79
.98
1.20
1.54
2.12
4.04
.50
Local
Diesel
--
.50
.99
1.67
1.89
2.61
3.38
7.10
6.16
All
Trucks
.24
.45
.83
1.04
1.26
1.86
3.01
8.71
2.07
Intercity
Gasoline
.23
.48
.90
1.14
1.34
1.87
2.48
5.28
.88
Intercity
Diesel
•
»
1.
1.
2.
3.
4.
9.
9.
23
50
00
65
38
60
56
78
28
Taken from Reference 12.
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Table 6
Average Fuel Economies for different Loads and Scenarios
(miles per gallon)
SAE
Driving Cycle:
Percent GVIW: 50
Local
100
Short
% diff .
50
Range
100 % diff.
Long
50 100
Range
% diff.
Truck Class
6 6.24
6 4.43
8
8
4.42
3.55
41
25
7.
6.
6.
5.
47
82
28
91
6.
5.
6.
4.
11
61
44
32
22.2
22
32
37
4.95 4.
5.09 4.
13 20
01 27
% GVIW = percent Gross Vehicle Test Weight
50% GVIW is used to simulate zero pay load (roughly)
100% GVIW is used to represent full pay load
% diff. = [(50% GVIW fuel economy/100% GVIW fuel economy)-1.00] X 100
Taken from Reference 13.
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LEGENO
Laeil
Start KM*
IMtrcily
OH Ho*
MEDIUM
LIGHT-HEAVY HEAVY-HEAVY
MEDIUM
USHT-HEAVY HEAVY-HEAVY
Fig. 1 - Average Fuel Economy by GVW Category
and Area of Operation (Gasoline)
Fig. 2 - Average Fuel Economy by GVW Category
and Area of Operation (Diesel)
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III. Historic Fleet-Average Conversion Factors
Historic fleet-average conversion factors are calculated
by VMT weighting the class-specific, conversion factors. The
VMT-weighting factor for each class is a product of: 1) the
annual VMT per vehicle per year, 2) the urban travel fraction,
3) the HDV sales fraction, and 4) the diesel or gasoline sales
fraction. The resulting diesel and gasoline VMT-weighting
factors are listed in Table 7. The individual factors that
make up the VMT weighting factor are discussed in -the
paragraphs below.
A. Annual Vehicle Miles Travelled
The annual VMTs per vehicle used for each vehicle class
were those given in the EEA report[1] ("VMTD" for diesel and
"VMTG" for gasoline in Table A-l) and came from the 1977 TIUS.
The relationships of these figures for the various classes
matched quite closely EPA estimates of lifetime VMTs per
vehicle. [14] Thus, the TIUS figures appeared reasonable for
use in MOBILES.
The TIUS information did not include buses, so an
equivalent annual VMT per bus had to be determined. While the
EEA report uses annual VMT per vehicle to calculate the
weighting factor and an analogous figure was derived and used
for buses, lifetime VMT per vehicle would actually be a more
appropriate measure of a vehicle's contribution to a model
year's lifetime emissions. This is true because the conversion
factors, as set out by EEA, are determined by model year and
apply throughout the entire life of that model year's
vehicles. When vehicles' lives are the same in terms of years,
the two approaches (annual and lifetime VMT) yield the same
results. However, the lives of buses are much longer than
other heavy-duty vehicles, so the annual approach would
underestimate their contribution to their model year's
•fleet-wide lifetime emissions. Thus, an equivalent annual
'transit bus VMT was estimated by multiplying the EEA annual
Class VIII VMT per vehicle of 62,500 miles by the ratio of
lifetime transit bus VMTs, to lifetime Class VIII VMT. This
results in a transit bus annual VMT of 45,00-50,000 miles as
illustrated in Table 8, depending on the figure used for
lifetime Class VIII vehicle VMT. Forty-five thousand annual
miles per vehicle was chosen as the best estimgae %ince the
lifetime VMT of HHDVs (including rebuilds) is more likely to be
near, the upper end of the range estimated in Table 8 as opposed
to the lower end.
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Table.7
Pre-1978 VMT Weighting Factors
Class
Diesel
lib
III-V
VI
VII
VIII
Bus
Gasoline
lib
III-V-
VI
VII
VIII
1962
.000
.040
.061
.246
.486
.167
.085
.491
.258
.068
.097
1965
.001
.042
.095
.158
.592
.112
.117
.455'
.247
.067
.113
1967
.001
.036
.093
.118
.652
.100
.141
.365
.308
.078
.108 .
1970
.000
.002
.062
.088
.764
.083
.199
.296
.332
.093
.080
1972
.000
.002
.027
.070
.817
.084
.210
.285
.375
.069
.061
1975
.000
.002
.044
.091
.652
.212
.409
.129
.377
.048
.038
1977
.001
.000
.063
.091
.791
.055
.562
.096
.286
.036
.021
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Table 8
Bus Annual VMT per Year
Year
1971
1972
1973
1974
1975
1976
1977
1978
1979
Vehicle Miles Total New
Operated (xlO6) Bus Sales
1,
1,
1,
I,
.1,
1,
1,
If
1,
Average 1,
*
** •
Annual
vehicle
Annual
vehicle
engines.
375.
308.
370.
431.
526.
581.
623.
630.
633.
497.
5
0
4
0
0
4
3
5
6
7
VMT]_
VMT of
VMT 2
VMT of
2
2.
3
4
5
4
2
3
3
f514
,904
,200
,818
,261
/745
,437
,805
,440
Miles/Sales Annual
(Lifetime VMT) VMTi*
547
450
428
297
333
666
428
474
366
,100
,400
,200
,000
,300
,100
,500
,900
,800
3,680 443,600
is calculated using a
529,000 from reference 18.
is calculated using a
600,000, which may even be
64,
53,
50,
35,
39,
78,
50,
56,
43,
52,
lifetime
lifetime
exceeded
638
200
591
100
400
700
600
100
300
Annual
VMT2**
59,
46,
44,
30,
34,
69,
44,
49,
38,
800
900
600
900
700
400
600
500
200
400 46,500
heavy-duty
heavy-duty
by rebuilt
Bus data taken from Reference 10.
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B. Urban Travel Fractions
The EEA report used urban travel fractions (listed as
"UVMTG and UVMTD" in Table A-l) derived from the 1977 TIUS
data. These urban travel fractions were based on the
assumption that trucks operating predominantly in "short range"
and "long range" applications are entirely rural while those
operating predominantly in "local" areas were entirely (100
percent) urban. EEA also examined an alternate assumption that
only 70 percent of all usage was in the predominant usage
category with the other 30 percent being split between the
other two usage categories. [1] EEA found this to have little
effect, so they used the urban travel fractions derived using
the 100 percent asumption. Upon examination, the 70 percent
assumption did appear to have a significant effect for a few
classes. In the example of the weighting procedure presented
below, if 70 percent of a vehicle's VMT occurs in its primary
use category, with the remaining 30 percent distributed between
the other two use categories, the local VMT fraction is 22.2
percent, rather than 13 percent which results from EEA's 100
percent assumption. Acknowledging this, a mid-range assumption
that 85 percent of a vehicle's VMT occurs in its primary use
category, with the remaining 15 percent distributed between the
other two use categories was used for the MOBILE3 urban VMT
fractions. The resulting urban fractions ("UFG" and "UFD" for
gasoline- and diesel-fueled vehicles, respectively) are given
in Table A-2. ^n example of the weighting procedure is
presented below.
Local Short Range Long Range
TIUS Primary Use Breakdown '13% 34% 53%
EEA VMT Fractions (100%) 13% 34% 53%
VMT Fractions (70% Assumption) 22.2% 33.6% 44.2%
MOBILES VMT Fractions (85%) 17.6% 33.8% 48.6%
^.Where:
17.6% = 0.85 x 13% + 0.075 x 34% + 0.075 x 53%
and
22.2% = 0.70 x 13% + 0.15 x 34% + 0.15 x 53%
C. Sales Fractions
The historic sales figures used in the EEA report [1] ("SF"
in Table A-l) were used as a base for the MOBILES sales
fractions. The Class II sales figures were revised to
represent Class lib sales, as only Class lib vehicles are
treated as HDVs. Sales figures for buses were taken from the
1981 Transit Fact Book (see Table 8).[10] These sales figures
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were divided by EEA total sales (revised with Class lib sales
replacing total Class II sales) to derive the sales fractions
listed in Table A-2. - .
D. Diesel Fractions and Gasoline Fractions
The historic diesel sales fractions used in the
VMT-weighting factors ("DF in Table A-l) were those derived by
EEA[1] from factory sales 'of U.S. domestic manufacturers and
exports from Canada to the U.S. The gasoline fractions are
simply. 1.0 minus the diesel fraction. These same diesel and
gasoline fractions are also listed in Table A-2. All transit
buses were assumed to be diesel-powered.[10]
IV. Future Class Specific Conversion Factors
Post-1977 class-specific gasoline and diesel conversion
factors (GCF and DCF, see Table A-4) were estimated using 1977
class-specific conversion factors and projected future
non-engine-related fuel economy improvements. Engine-related
fuel economy improvements affect both BSFC and fuel economy
(BSFC decreases as fuel economy increases) and, thus, do not
affect the conversion factor. Future conversion factors are
calculated by dividing the historic conversion factor by 1.0
plus the non-engine-related fuel economy improvement (in terms
of percent) that is predicted to occur between the previous
year and the year in question. The specific non-engine related
fuel economy improvements are discussed in the following
paragraphs.
A. Future Non-Engine Related Fuel Economy Developments
Several studies of future non-engine-related fuel economy
improvements were conducted and submitted to EPA for use in
deriving these conversion factors. The data and estimates were
reviewed and that which was substantiated was used here.
The estimates of fuel economy improvements were derived
according to GVW class (Classes Ilb-IV or light heavy-duty
vehicles (LHDVs), Classes Vl-VIIIa or medium heavy-duty
vehicles (MHDVs), and Class Vlllb or heavy heavy-duty .vehicles
(HHDVs)) as specific improvements will affect each class
differently. These improvements are all detailed and
referenced' in Tables A-5 through A-8, and summarized in
Table 9. Improvements to LHDVs are listed in Table A-6, MHDVs
in Table A-7, and HHDVs in Table A-8. Each area of improvement
is discussed in detail below.
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Table 9
Total Non-Engine-Related Fuel Economy Improvements
Diesel (Percent Improvement)
Years Class 2b Class 6 Class 7 Class 8a Class 8b Buses
1977-1982 2.891 0.317 0.375 0.407 6.038 0.375
1982-1987 0.663 5.018 4.904 4.865 1.677 4.904
1987-1992 2.066 0.610 0.544 0.474 1.025 0.544
1992-1997 2.399 1.104 1.301 1.353 1.900 1.301
Gasoline (Percent Improvement)
Years Class' 2b Class 6 Class 7 Class 8a
1977-1982 2.919 2.330 2.130 1.876
1982-1987 0.666 3.512 3.459 3.516
1987-1992 2.061 1.906 1.245 2.766
1992-1997 2.399 2.086 2.840 1.667
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1. Weight Reduction
In EEA's report for MVMA, [1] EEA cites that a 500 Ib.
weight reduction was reported by Ford and GM for light-duty
trucks (LDTs) in 1979-80 for a 6.6 percent fuel economy
improvement. EEA[1] assumed that this same weight reduction
would be made on LHDVs and that a similar fuel economy
improvement would occur on these heavier vehicles. They
estimated that 50 percent of the fleet would experience this
weight reduction in each of the 1977-82 and 1987-91 time
periods for a net 3.3 percent fuel economy improvement for each
time period. There were no accompanying data to verify neither
that these weight reductions occurred on LDTs or LHDVs nor that
the 500 Ib. weight reduction caused a 3.3 percent improvement
on LDTs or LHDVs. The weight reduction figures used for LHDVs
in MOBILES are listed in Table A-6.
In general, there is greater incentive to improve LOT fuel
economy compared to LHDV fuel economy because: 1) LDTs are
labeled with EPA-measured fuel economy, and 2) LDTs must comply
with NHTSA-set fuel economy standards. Given the lack of
substantiation presented, only the first fuel economy
improvement was acknowledged (3.3 percent in 1979-80).
Additional data in this area could change future projections.
No fuel economy improvements were projected due to weight
reduction for MHDVs or HHDVs, based on IHC[16] information
which indicated that weight reduction is not valued highly by
purchasers of these vehicles and, thus, is unlikely to occur.
Were any weight reduction to occur in MHDVs or HHDVs, it would
likely be offset by an increase in payload, thus there would be
no-fuel economy benefit.
2. Rolling Resistance (radials and advanced radials)
EPA used IHC data [17] from vehicle track tests as the
primary basis for reduced rolling resistance benefits (i.e.,
,use of radials and advanced radials). Fuel economy
improvements were measured over three driving cycles
(city/suburb/highway). EPA used the city figures as the
average speed of this cycle matched that of EPA's urban driving
cycle.
The percent fleet penetrations for radials reflect those
used in the EEA reports (reference 15, if applicable, or if
not, reference 1), and were supported by historic usage and
cost benefit analysis supplied by IHC. There were a couple of
exceptions to this. One, no penetration of advanced radials
was made for LHDVs since the annual mileage of these vehicles
is so low and because production technology for this size tire
would have to be oriented specifically for LHDV use. Two, the
-------
-19-
fuel economy improvement associated with use of advanced
radials on MHDVs estimated by IHC (8 percent) was lowered by 2
percent (in the absence of any supporting data) , because their
analagous estimate for HHDVs was 2 percent higher than the data
showed. (IHC focused on a blend of city and suburban driving
rather than on city driving alone.)
3. Aerodynamics
Aerodynamic improvements for MHDVs and HHDVs are taken
primarily from IHC data for city driving.[171 The penetrations
were taken from EEA, and were supported by historic usage and
cost benefit analysis supplied by IHC.
EEA's[15] LHDV aerodynamic-related fuel economy
improvements were based again on GM and Ford LOT body redesign,
and they assume that these improvements will also be seen on
LHDVs. Only body improvements are specified; no add-ons are
expected for LHDVs. . No evidence was submitted that these
improvements carried over the LHDVs, nor that the fuel economy
improvement was 3.4 percent. There is no guarantee that LOT
modifications would make their way to LHDVs. Thus, without
data to support this projection, no fuel economy improvement
could be accepted for LHDVs.
4. Drivetrain Lubricants
Non-engine-related drivetrain lubricants are projected to
improve fuel economy by 1.5 percent and to affect the entire
fleet by 1997. All sources confirmed this improvement and both
the availabiltiy and cost/benefit of such lubricants appeared
reasonable.
5. Fan Drives
The fuel economy improvements resulting from fan drives
were also taken from IHC's data. [17] All sources predicted 100
"percent vehicle penetration of fan drives by 1992 and
historical data supported this trend, so this figure was used
by EPA. The 1982 penetration of 50 percent represents a
compromise of the two available estimates.
6. Overdrive
LHDVs are. the only vehicles for which overdrive
improvements apply. MHDVs and HHDVs already have overdrive and
have used overdrive to boost fuel economy for years, thus there
is very little room for overdrive improvement to increase fuel
economy for these vehicle classes. LHDVs are now incorporating
overdrive to increase fuel economy. Manual overdrive
-------
-20-
contributes a 5 percent fuel economy improvement according to
both EEA[15] and IHC.[16] MOBILES uses EEA's percent
penetration, which is confirmed by that of IHC. Automatic
overdrive fuel economy improvements are greater than manual
according to EEA[15] and IHC, [16] but MOBILES uses the same
percent improvement for manual as for automatic overdrive.
There was not sufficient data to justify EEA's high fuel
economy improvements for automatic overdrive and a 5 percent
improvement for essentially the entire LHDV fleet appeared
reasonable for urban use.
7. Electronic Transmission Control (ETC)
EEA[15] estimated a 6.0 percent fuel economy improvement
for LHDVs due to ETC based on LOT experience. In conversation
with Ford, [19] they indicated that the driving force behind ETC
was stringent emissions standards and that ETC will not be used
in LHDVs until stringent LHDV (i.e., vehicle-based) emissions
standards are put into effect. Therefore, no fuel economy
benefit was projected for LHDVs due to use of ETC.
8. Speed Control
EEA[1] and IHC[16] projected similar speed control
improvements with EEA projecting slightly higher percent fleet
penetration. Speed control applies mainly to long range
vehicles and over-the-road usage, however, these vehicles do
accumulate for some of their mileage in urban areas (7.5
percent was used for MOBILES VMT fractions) and some of this
mileage is at fairly constant speeds (e.g., freeway travel).
For this reason, the long range speed control improvements were
acknowledged. Even though fuel economy of local or short range
vehicles would not benefit significantly from speed control
improvements, urban fuel economy would increase some due to the
long range vehicle fraction. EEA and IHC's common percent fuel
economy improvement with EEA's penetration were used here.
B. Application of Non-Engine-Related Fuel Economy
Improvements
The above non-engine-related fuel economy improvements
were applied uniformly across the fleet by EEA.[1] (That is,
local, short-range, and long-range use categories all received
the same improvements and rural and urban fuel economies are
both increased to the same degree. This contradicts the logic
that, in nearly all cases where less than 100 percent of the
fleet is affected, a fuel-saving change or device will be
applied first to those vehicles where it is most cost
effective, which are those vehicles with the highest annual
mileage. Based on the 1977 TIUS, as would be expected, the
long-range vehicles had the higher annual mileages, the
-------
-21-
short-range vehicle had the next highest, and the local
vehicles the lowest. Thus, here these improvements were
applied to long-range (over-the-road) vehicles first,
short-range vehicles secondhand local vehicles last.
If the percent fleet affected was less than the percent of
vehicles used for long range transport then only long range
vehicles were credited with fuel economy improvements. The
percent of fleet affected had to be greater than both the
combined long range and short range vehicle use fractions in
order to credit any fuel economy improvement to the short range
(local) vehicles. This method credits most fuel economy
improvements that affect only a small fraction of the fleet to
long range and short range vehicles, which each only account
for 7.5 percent of the urban travel fractions. The fraction of
each class1 vehicles falling in each category was taken from
the 1977 TIUS, as outlined in the EEA report. [1] The overall
effect of a given technology is dependent on the degree that
the technology is applied throughout the class and on the
breakdown of the class between the various use categories.
After all of the future non-engine-related fuel economy
improvements are calculated for each class and time period,
they are applied to the historic class-specific (1977)
conversion factors to yield future class-specific conversion
factors. Some of the fuel economy improvements discussed had
already penetrated a small portion of the fleet by 1977, and
their increasing benefits were realized later as a larger
percent of the fleet incorporated those improvements. This
i.977 baseline penetration was subtracted from the 1982
penetration to obtain the net percent improvement from 1977 to
1982. This procedure was repeated for each 5-year interval up
to 1997. These future class-specific conversion factors are
shown in Table 10.
V. Future Fleet-Average Conversion Factors
A. Calculation of Post-1977 Fleet-Average Conversion
Factors
Post-1977 fleet-average conversion factors (see .Table 2)
were calculated using the future GVW class-specific conversion
factors (Table 10) and future VMT-weighting factors (Table 11) .
The latter were defined in the same manner as the pre-1978
weighting factors and are described below.
B. Vehicle Miles Travelled
The same gasoline and diesel annual VMTs specified in the
EEA report[1] were used here ("VMTG" and "VMTD", respectively,
in Table A-4) . The previously discussed 45,000 annual VMT per
-------
-22-
Table 10
Class
Diesel
Ilb-IV
VI
VII
Villa
Vlllb
Bus
Gasoline
Ilb-IV
VI
VII
villa
1982
.970
1.865
2.260
3.002
3.190
3.989
.845
1.536
1.690
2.083
1987
.964
1.776
. 2.154
2.863
3.385
3.802
.840
1.484
1.634
2.012
1992
.944
1.765
2.142
2.849
3.106
3.782
.823
1.456
1.613
1.958
1997
.922
1.746
2.115
2.811
3.048
3.733
.804
1.427
1.569
1.926
-------
-23-
Table 11
Post-1977 VMT-Weighting Factors
Class
Diesel
Ilb-IV
VI
VII
Villa
Vlllb
Bus
Gasoline
Ilb-IV
VI
VII
Villa
1982
.126
.026
.106
.244
.420
.078
.882
.041
.074
.003
1987
.189
.043
.234
.028
.421
.086
.825
.046
.124
.005
1992
.259
.041
.209
.031
.393
.072
.830
.046
.121
.003
1997
..247
.047
.209
.034
.394
.070
.845
.046
.109
.000
-------
-24-
vehicle for transit buses was used here also. These figures
are very similar to the pre-1978 annual VMTs and are again
consistent with EPA's own estimates . of lifetime mileage
relationships between the various classes.
C. Urban Travel Fractions
As was done with respect to the pre-1978 urban travel
fractions, the urban travel fractions were modified using the
TIUS vehicle use pattern and the 85/7.5/7.5 breakdown between
usage categories. Here, a second change was made as well to
take into account the dieselization of the fleet.
As the diesel engine is essentially a fuel-saving
technology, like those discussed in the previous section,
future dieselization is basically applied to long-range
vehicles first. However, a slight deviation was made here from
the strict long-range, then short-range, then local approach.
The 1977 TIUS measured dieselization by class and use category
and some diesels were used in short-range and local applicatons
before all long-range applications were dieselized. Thus,
further dieselization was assumed to occur according to the
1977 long-range/short-range/local diesel breakdown until all
long-range applications were dieselized. After that, diesels
were added according to the 1977 short-range/local diesel
breakdown. The class-wide (gasoline and diesel) urban travel
fractions were held constant using historical values, but the
individual gasoline and diesel urban fractions changed from
year to year depending on the degree of dieselization. The
gasoline and diesel urban travel fractions used in MOBILES are
listed in Table A-4 (UFG and UFD) .
D. Diesel Sales Fractions
The diesel penetration (or diesel sales fractions) used
here were taken directly from EEA's report.[1] These diesel
penetrations are somewhat lower than earlier EPA projections.
However, this is reasonable given that projections of fuel
availability and price are more optimistic now than they were
2-3 years ago. Also, the figures do closely match information
presented to EPA during recent heavy-duty engine rulemaking
actions. The gasoline fractions are simply one minus the
diesel fractions. These fractions are also listed in Table A-4
("DF").
E. Sales Fractions
The breakdown of heavy-duty sales between the various
classes (sales fractions) used here for post-1977 ("SF" in
Table A-4) are based on those contained in the EEA report. [1]
-------
-25-
Bus sales (not addressed by EEA) were derived by increasing an
average historic annual sales figure from the 1981 Transit Fact
Book by approximately ten percent over each 5-year period to
represent projected sales growth. These class-specific sales
(shown in Table 12) were divided by total sales to get the
sales fractions ("SF" in Table A-4).
-------
-26 -
Table 12
Post-1977 HDV Sales Volume (gasoline and diesel)
Light .. Medium Heavy
Year IIB-IV V VI VII Villa Villa Buses
1982 305,000 1,333 23,099 53,248 6,350 64,180 5,000
1987 428,000 - 35,000 1,210,000 10,000 115,000 5,500
1992 450,000 - 37,000 130,000 13,000 140,000 6,000
1997 470,000 - 41,000 135,000 14,00 150,000 6,500
Taken from Reference 1, except for buses,
-------
-27-
VI. Summary of Results
The fleet-average emission conversion factors (in units of
BHP-hr/mi) used in MOBILE3 are listed in Tables 1 and 2.
MOBILES pre-1978 class-specific conversion factors are listed
in Table A-3. The non-engine-related fuel economy improvements
detailed in Tables A-5 through A-9, and summarized in Table 9,
were applied to the 1977 class-specific conversion factors to
develop the post-1977 class-specific conversion factors listed
in Table 10. The past and future class-specific conversion
factors were weighted by urban vehicle miles travelled to
calculate the fleet average conversion factors. The weighting
factors used are detailed in Tables A-l through A-4 and Table
A-6. Figures 3 and 4 illustrate the comparison between MOBILES
and EEA [l]f historic and future gasoline and diesel fleet
average conversion factors.
The projected future fleet-average conversion factors show
a steady decrease as time goes on, due to increased fuel
economy. Diesel conversion factors, decrease more rapidly than
gasoline conversion factors. MOBILE3 conversion factors are
higher than those projected by EEA for three primary reasons.
One, EEA included Class Ila vehicles in their pre-1978
analysis, which is inappropriate since these vehicles are
treated as light-duty trucks in MOBILES. Two, the MOBILE3
urban'VMT fractions for the heaviest diesel classes are larger
than those of EEA, due to an attempt to more reasonably
extrapolate urban VMT from primary truck usage (local, short
range, and long range). Three, EEA estimates somewhat greater
fuel economy improvements and applies these fuel economy
improvements equally to local, short-range, and long-range
vehicles. In MOBILES, the • somewhat lower fuel economy
improvements are applied to long-range vehicles first, then
short-range, and then local. This lowers the impact of the
fuel economy improvements since long-range vehicle usage only
comorises a small fraction of urban VMT.
-------
o
£-•
U
O
M
UJ
(4
2
O
U
3.50
3.25
3.00
2.75T
2.50
2.25
2.00
1.75
1.50
1.25
1.00
.75
.50
.25
0
FIGURE 3
PRE-1978 FLEET AVERAGE CONVERSION FAL'IOKS
MOBILE3 PIESEL
EEA DIESEL
CD
I
MOBILES GASOLINE
EEA GASOLINE
1962 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77
MODEL YEAR
-------
o
H
U
<
(M
2
O
H
(/I
«
w
>
3
O
3.5D
3.25
3.00
2.75
2.50
2.25
2.00
1.75
1.50
1.25
1.00
.75
.50
.25
0
FIGURE 4
POST-1977 FLEET.1 AVERAGE CONVERSION FACTORS
MOBILES DIESEL
M
VO
I
EEA DIESEL
-*—*-
-* * « *MOBILE3 GASOLINE
GASOLINE
t *
1978 79 80 81 82 33 84 85 86 87 88 89 90 91 92 93 94 95 96 97
MODEL YEAR
-------
-30-
VII. Recommendations
The future gasoline and diesel- conversion factors
presented here are based on estimates and projections. There
are several areas where the present degree of uncertainty' is
fairly high and where further data could significantly improve
the accuracy of the results.
The most important area of concern is fuel economy. Better
documented data on current urban fuel economy is needed, since
the TIUS only addresses 'nationwide fuel economy and the
accuracy of the submittals by surveyees is unknown. Equally
important is the need for further information on the effects of
future technology on urban fuel economy improvements. This is.
the main facto'r in projecting future conversion factors,
assuming fuel density will not change significantly in the next
25 years. The urban fuel economy impact of technological
developments in areas such as radial tires, lubrication,
aerodynamic drag reduction, and speed control are not well
known and the penetration of these technologies into the
heavy-duty vehicle market is quite dependent on future fuel
prices and manufacturers' marketing strategies. Any new data
in these areas will be very useful in improving future
projections of the emission conversion factors.
A second important area for further study is the estimation of
the urban VMT fraction for the various classes of heavy-duty
vehicles. Again, the TIUS only yields a surrogate for urban
VMT fraction and more accurate estimates could be quite
different.
-------
-'31-
References
1. Historical and Projected Emissions Conversion Factor
and Fuel Economy for Heavy-Duty Trucks 1962-2002, prepared for
Motor Vehicle Manufacturers Association by Energy and
Environmental Analysis, Inc., 1655 N. Fort Mayer Drive,
Arlington, Virginia 22209, December 1983.
2. Code of Federal Regulations, Protection of
Environment, 40, _ 600.113-78, revised as of July 1, 1983.
3. "MVMA National Diesel Fuel Survey," Summer Season
Report, July 15, 1983.
4. "MVMA National Gasoline Survey," Summer Season,
July 15, 1983.
5. "Heavy-Duty Engine Emission Factors Program Update,"
Baines, T, U.S. EPA, OAR, QMS, ECTD, SDSB, May 17, 1984.
6. Emissions From Heavy-Duty Engines Using the 1984
Transient Test Procedure Volume II - Diesel, Southwest Research
Institute, San Antonio, Texas.
7. "Analysis of Fuel Economy and Vehicle Use Data From
the TIUS, 1977 Truck Inventory and Use Survey, Lax, D. L. , SAE
Paper No. 810388, February 1981.
8. Information received during a telephone conversation
in April with K. G. Duleep, Director of Engineering, Energy and
Environmental Analysis, Inc.
9. "Evaluation of General Motors Heavy-Duty Engine
Proposal," Attachment to EPA Memo from Chester J. France, SDSB,
to Richard Wilson, QMS,. May 16, 1983.
10. Transit Fact Book, American Public Transit
'Association, October, 1981.
11. Information received during a telephone call in
November with Marian Warner-Selph, Research Scientist,
Department of Emissions Research, Southwest Research Institute.
12. "Trucking Activity and Fuel Consumption-1973, 1980,
1985, and 1990", Jack Faucett Associates, Inc., orepared for
Federal Energy Administration, July 1976
13. "Derivation of Heavy-Duty Diesel Engine Average
Usage Period," U.S. EPA, OAR, QMS, ECTD, SDSB, July 1983.
-------
- 32-
References (cont'd)-
14. "Documentation of Market Penetration Forecasts,"
addendum to the report entitled "Historical and Projected
Emissions Conversion Factor and Fuel Economy for Heavy-Duty
Trucks, 1962-2002," prepared for MVMA by EEA, April 12, 1984.
15. Letter from T. M. Fischer, Director, Automatic
Emission Control, General Motors, to Richard A. Rykowski,
Senior Project Manager, U.S. EPA, Standards Development and
Support Branch.
16. Meeting with International Harvester Corporation,
MVMA and EPA, on the topic "Heavy-Duty Engine Fuel Economies
and Future Fuel Economy Improvements," April 10, 1984.
17. Letter from R. W. Glotzbach, P.E., International
Harvester Corporation to Mr. Charles Gray, Jr., Director,
Emission Control Technology Division, U.S. EPA, April 19, 1984.
18. "Trends in Heavy-Truck Energy Use and Efficiency,"
Roberts, Glenn F. and David L. Greene, Oak Ridge National
Laboratory, TM-8843.
19. Information received during a telephone conversation
in April with Mike Schwartz, Ford Motor Company.
-------
-33-
Appendix
-------
_34.
CLASS
YEAR
VMTG
VMTD
UVMTG
UVMTD
MPGG
MPGD
BSFCG
BSFCG
SF
DF
GF
UFG
UFD
.GCF
DCF
GCFD
GCFN
DCFN
DCFN
i
TEG
Definitions of Headings for Appendices
Class of heavy-duty vehicle that data applies to.
Year data applies to.
Gasoline annual vehicle miles travelled per vehicle.
Diesel annual vehicle miles travelled per vehicle.
Urban fraction of gasoline vehicles miles travelled.
Urban fraction of diesel vehicles miles travelled.
Miles'per gallon for gasoline fueled vehicles.
Miles per gallon for diesel fueled vehicles.
Gasoline fueled vehicle's brake specific
consumption (Ib/BHP-hr).
brake specific
fuel
fuel
Diesel fueled vehicle's
consumption (Ib/BHP-hr).
Sales fraction.
Diesel fraction of sales.
Gasoline fraction of sales.
Urban fraction of gasoline vehicle miles travelled,
same as UVMTG.
Urban fraction of diesel vehicle miles travelled,
same as UVMTD.
Gasoline conversion
(BHP-hr/mi).
factor,
class specific
Diesel conversion factor, class specific (BHP-hr/mi).
Gasoline conversion factor -. denominator (product of
VMTG, SF and GF).
Gasoline conversion factor - numerator (product of
GCFD and GCF).
Diesel conversion factor - denominator (product of
VMTD, UFD, SF and DF).
Diesel conversion factor - numerator (product of
DCFD and DCF).
Percent divided by 100 of fuel economy improvement
over previous year listed for gasoline fueled
vehicles.
-------
-35-
TED Percent divided by 100 of fuel economy improvement
over previous year listed for diesel fueled vehicles.
-------
Table A-3
MOBILE3 Pre-1978 Class-Specific
Conversion Factors and Fleet-Average VMT Weighting
CLASS
2.
2.
2.
2.
2!
2.
2.
3.
3.
3.
3.
3.
3.
3.
3.
6.
6.
h.
6.
6.
6.
6.
7.
7.
7.
7.
7.
7.
7.
7.
8.
8.
8.
8.
8.
8.
H.
9.
9.
9!
9.
q.
YK
1*62,
1970.
19^2.
197b.
1977.
1976.
1*62.
l*ob.
1 * o 7 •
1 * / 0 .
l*7b.
1977.
1*78.
1-^02.
l*6b.
I*o7.
1*70.
1977.
1*76.
1*62.
l*6b.
1*67.
1 -* 7 U •
\^lt.
1977.
* * — —
1 * 7 o .
1*72.
1975.
1*77.
l*7o.
1 * o 7 .
ir/u.
1972..
1*77.
or
1.00000
.**000
. * * 7 0 0
. ***0 0
i.OOoOO
i .00000
.***oo
1 .00000
.*OOlU
•*/4bO
.*6*40
. *-»6*0
• *•>> 2i-
. *^o3'J
1.00000
1 .oooOO
.90000
. 8*300
.*u600
* * c 4 0 0
• 9o*0 1'
. *o^uu
. * 0 0 0 0
. 6 ^r^O1)
,b6*0n
.30300
.6<:ino
.6u7CO
. DD^OO
. bbUJO
.4cl2ou
. 3 e 3 u 0
.1*4700
.Jlbui'
,L . 021
1/6.041
171.4*5
364.011
616.511
563.490
404. 053
30 /. 140
203.741
104.370
10J.753
-0.
-0.
-0.
-o.
-o.
-0.
-0.
-0.
446.1*3
bbrt.02u
664. D04
d78.*dl
*20.27/
1*52.102
2423. 7b6
2412.^41
3408.625
2*bO.Oo2
2366.^*3
I8d7.663
1783.246
639.215
547. /4b
981.056
2141.10*
1939.661
24ott.407
2574.106
2*75. Jbb
3303. *25
2227. Ib3
1814. JOJ
03*. /14
5*0 .^2b
091.066
/92.316
598.960
455.0/0
303. *05
293.162
1125.121
1229.244
1 lbO.*68
647.004
6b9.bbl
447. doO
221.423
214.934
-0.
-0.
-0.
-0.
-0.
-0.
-0.
-n.
««.
DCFO
0.
1.174
2.0*6
.923
0.
0.
-------
Table A-4
MOBILES Post-1977 Input Data
CLASS
1
1
1
1
1
2
2
2
2
2
6
6
6
6
6
7
7
7
7
7
8
8
8
a
8
9
9
9
9
9
0
0
0
0
0
r-,1
1977
• '19*2
1
1
1
9" 7
997
1
1
1
1
1
1977
1
1
1
1
' 1
1
1
1
1
1
A
1
1
1
1
1
1
9^2
9H7
992
997
977
9*2
987
992
997
977
982
987
992
997
977
9«2
1
1
1
1
1
1
1
1
1614
lbl<*
161<*
1614.
Ibl4
97J4
97j4
9734
9/J4
9 7 j<*
12^3
12*3
1223
1223
1223
abbO
bsbO
sbfaO
15560
1
1987
1
992
1997
1
1
1
i
1
977
9-i2
9H7
v
-------
-40-
Table A-5
Abbreviations for Referencing
Future Non-Engine Related Fuel Economy Improvements
EEA
IHC
GM
ORNL
Energy and Environmental Analysis, due.
(contracted by MVMA)
International Harvester Corporation
General Motors
Oak Ridge National Laboratory (ORNL/TM-8843,
Roberts and Greeve)
MOBILES = Estimates used in MOBILE3
[#] = Referenced source of estimate
-------
Table A-6
Class IIB-IV—Light Heavy-Duty Vehicles
Future Non-Engine Related Fuel Economy Improvements
Weight Reduction
. % Penetration (cumulative)
Source % Imprv. 1977 1982 1987 1992 1997
EEA [1] 6.6 0 50 50 100 100
[15] 6.6 based on LDTs/ no data to justify historical
or future EEA weight decrease.
MOBILES 6.6 0 50 50 50 50
Radials & Advanced Radials
% Penetration (cumulative)
Source
EEA [1]
EEA [1] ,
IHC [17]
MOBILE3
MOBILES
% Imprv. 1977 1982 1987
4.0 (radial) 35
8.0 (adv.rad) 0
1.4/2.0/2.5 (radial)
1.4 (radial) 35
0.0 (adv. rad)
47.
12.
(ci
55
5 60
5 25.0
1992
72.5
37.5
1997
85
50
ty/suburb/hwy)
70
80
90
Aerodynamics (add-on) None
Aerodynamics (body)
% Penetration (cumulative)
Source % Imprv. 1977 1982 1987 1992 1997
•EEA [1] . 3.4 0 50 50 100 100
MOBILES 0
Drivetrain Lubricants
% Penetration (cumulative)
Source % Imprv. 1977 1982 1987 1992 1997
EEA [1] 1.5 0 0 33.3 66.7 100
MOBILES 1.5 0 0 33.3 66.7 100
Accessories (None)
-------
Table A-6
Class IIB-IV—Light Heavy-Duty Vehicles
Future Non-Engine Related Fuel Economy Improvements
Weight Reduction
% Penetration (cumulative)
Source % Imprv. 1977 1982 1987 1992 1997
EEA [1] 6.6 0 50 50 100 100 "
[15] 6.6 based on LDTs, no data to justify historical
or future EEA weight decrease.
MOBILES 6.6 0 50 50 50 50
Radials & Advanced Radials
% Penetration (cumulative)
Source %
EEA [1]
EEA [Ij
IHC [17]
MOBILES
MOBILES
Aerodynamics
Imprv. 1977
4.0 (radial) 35
8.0 (adv.rad) 0
1.4/2.0/2.5 (radial
1.4 (radial) 35
0.0 (adv. rad)
(add-on)- None
1982
47.5
12.5
1987
60
25.0
1992
72.5
37.5
1997
85
50
) (city/suburb/hwy )
55
70
80
90
Aerodynamics (body)
% Penetration (cumulative)
Source % Imprv. 1977 1982 1987 1992 1997
EEA [1] 3.4 0 50 50 100 100
MOBILES 0
Drivetrain Lubricants
% Penetration (cumulative)
Source % Imprv. 1977 1982 1987 1992 1997
EEA [1] 1.5 0 0 33.3 66.7 100
MOBILES 1.5 0 0 33.3 66.7 100
Accessories (None)
-------
Table A-6 (cont'd)
Class IIB-IV—Light Heavy-Duty Vehicles (cont'd)
Future Non-Engine
Related Fuel Economy Improvements
Automatic Overdrive
% Penetration (cumulative)
Source
EEA [1]
[15
MOBILE3
Manual
Source
EEA [1]
[15
MOBILE3
ETC.
Source
EEA [1]
MOBILE3
% Iraprv.
9.6
] 10.0
5.0
Overdrive
% Imprv.
5.0
] 5.0
5.0
% Imprv.
6.0
0.0
1977 1982
1987
1992
0 0 16.7 33.3
0 0 16 32
% Penetration (cumulative)
1977 1982
1987
0 10 20
0 12.5 25
0 10 20
% Penetration (
1977 1982
0 0
1987
0
1992
30
37.5
30
cumulative)
1992
25
1997
50.0
48
1997
40
50
40
1997
50
-------
Table A-7
Class Vl-VIIIa—Medium Heavy-Duty Vehicles
Future Non-Engine Related Fuel Economy Improvements
Weight Reduction (none)
Radials
Source % Imprv.
4
6
% Penetration (cumulative)
1977
1982
13.5
EEA [1]
IHC [16]
IKC [17] 3.2/4.9/5.3 (city/suburb/hwy)
1987
13.5
1992
1997
0
ORNL [18]
GM [13] 3-5/4-8/5-9
MOBILES 3.2
Advanced Radials
10.6
14
50 (max. penetration)
14
Source %
EEA [1]
IHC [16J
MO BILE 3
Aerodynamics
Aerodynamics
Source %
EEA [1]
EEA [15]
IHC [16]
*
Imprv. 1977
8 0
8 0
6.0 0
(body) - none
(add-on)
\
Imprv. 1977
6 3
6 3
4.8 3
i Penetrat
1982
0
0
0
fc Penetrat
1982
6.3
5
ion (cumulative)
1987 1992
6.25 15
0 6
6 15
ion (cumulative)
1987 1992
8.3 11.3
7 13
1997
30
14.75
30
1997
16.3
18
23
IHC [17] 2.5/6.8/12.3 (city/suburb/hwy)
GM [13] 1.1
MOBILES
2.5
13
20
-------
Table A-7 (cont'd)
Class Vl-VIIIa—Medium Heavy-Duty Vehicles (cont'd)
Future
No n- Engine
Related
Fuel Economy Improvements
Drivetrain Lubricants
% Penetration (cumulative)
Source %
EEA [1]
IHC [16]
IHC [17]
MOBILES
Fan Drives
Source %
EEA [1]
IHC [16]
IHC [17] 5.3/
ORNL [18]
MOBILE3
Speed Control
Source %
EEA [1]
IHC [16]
MOBILE3
Imprv.
1.5
3.0
1.5
1.5
1977
0
0
0
1982
0
0
0
1987
33
12.5
33
% Penetration (
Imprv.
4.0
4.0
5.1/4.2
5.3
1977
18.0
0.0
1982
73
15.0
1987
100
80
1992
67
50
67
cumulative)
1992
100
100
1997
100
100
100
1997
100
100
(ci ty/suburb/hwy )
16.0
18
100%
50
maximum
100
% Penetration (
Imprv.
6.0
6.0
6.0
1977
0
0
0
1982
5
0
0
1987
6.7
2
5
penetration
100
cumulative)
1992
10
5
10
100
1997
15
10
15
-------
Table A-8
Class VHIb—Heavy Heavy-Duty Vehicles
Future Non-Engine Related Fuel Economy Improvements
Weight Reduction (none)
Radials
Source % Imprv. 1977
EEA [1] 6.0 26
EEA [15] 6.0 26
IHC [16] 8.4
IHC [17] 6.8/10.8/9.9
ORNL [18]
GM [13] 3-5/4-8/5-9 '
GM [13] 6.4
MOBILES 6.8 25
Advanced Radials
% Penetration (cumulative)
1982
65
1987
45
1992
20
1997
70 max. penetration
50 50 25" 0
(c i ty/s uburb/hwy)
100 percent max. penetration
100 percent max. penetration
65
45
20
% Penetration (cumulative)
Source
EEA [1]
IHC [16]
% Imprv.
12.0
12.4
1977
0
0
1982
1.7
1.5
1987
25
31.5
1992
50
56.5
1997
70
81.5
IHC [17] 10.2/15.0/13.8
1MOBILE3 10.2
(city/suburb/hwy)
0 1.7 25
50
70
-------
Table A-8 (cont'd)
Class Vlllb—Heavy Heavy-Duty Vehicles (cont'd)
Future Non-Engine
Related Fuel Economy Improvements
Aerodynamics (body) - none
Aerodynamics (add-on)
Source % Imprv.
EEA [1] 6.0
EEA [15] 6.0
IHC [16] 5
IHC [17] 2.4/6.7/10.9
GM [13] 4.3-9
ORNL [18]
MOBILE3 2.5
Drivetrain Lubricants
Source % Imprv.
EEA [1] 1.5
IHC [16] 3.0
. [17] 1.5
MOBILE3 1.5
Fan Drives
Source % Imprv.
EEA [1] 6.0
EEA [15] 4.0
IHC [16] 6.0
IHC [17] 6.8/6.7/6.9
% Penetration (cumulative)
1977 1982 1987 1992 1997
10 22 34 48 60
58 (maximum penetration)
'10 17.5 60 60 60
( c i ty/suburb/hwy )
.11.2 24.4 50 max. penetration
10 22 34 48 58
% Penetration (cumulative)
1977 1982 1987 1992 1997
0 . 0 33 67 100)
0 0 12.5 50 100
100 (maximum penetration)
0 0 33 67 100
% Penetration (cumulative)
1977 1982 1987 1992 1997
45 98 100 100 100
48 48 48 48 48
98 100 100 100
( c i ty/suburb/hwy )
ORNL [18]
MOBILES
6.8
47.7 100 (maximum penetration)
48 98 100 100 100
-------
Table A-8 (cont'd)
Class VHIb—Heavy Keavy-Puty Vehicles (cont'd)
Future Non-Engine Related
Speed Control
Source
EEA [1]
IHC [16]
MOBILE3
% Imprv.
5.0
5.0
5.0
%
1977
8
-
8
Fuel Economy Improvement
Penetration (cumulative
1982
6
-
8
1987
18
12
16
1992
30
24
30
s
)
1997
50
4.4
50
-------
Table A-9
EEA Post-1977 Input Data
CLASS
c:e:-4
i:ibi4
•::B34
C-B34
C2F34
f.^BH
Ctf*05
i:n*(p05
C«?kikl5
Ck»tfk'5
l'*l!!lk»5
i.»»ia««5
C **•*<:>
C-?0*»6
•.>*k'B'0
1. «tlH.';-
'. t^kHic-
r Mviiitt'
'. nrw
t **pv* /
-Ik^ki7
i rfi.ti47
i. I?**** 7
C k»t?P /
i* jt' i^ i
i. rk't? 7
C«»oCl
r ii • '• f '
i. M-}'.' i
'". r-S"l» 1
i^tfi.-!
i. rf'SC 1
C k'yC 1
C«*?:G2
i.k'joi
CrftCi.
Cf^C-I'
1:0*0:
Croc-.:
TEAR
1-/79
1982
19i/
1992
1997
2002
1979
1982
19*7
1V-V2
1997
2002
1979
i-'*:
1-VS7
1 "V 9 1
1i-' ™
y r
4> K*k* C
1 /TV
1 *> 2
1 5 "•?
l ' '.'
1 9 /k
199.'
i>'tfl
IV 7V
IOO "
y?..
l'yS7
1992
1 997
2 ••"••? 2
1979
l'V?2
1 V!-:'/
19 V2
1997
IS'k'l
VM ; r-
1 1 •• 1 4
; i A 1 4
11-14
1 1-14
1 1614
11614
997 1
9979
9979
•?'/79
?97V
9979
9-34
•y7V4
'•7-4
y 7 ": 4
v7 '.••;
/ " "• J
/ / ^ "4
1 U. .
i .:. •
i
1 » t.
i ^. .
1 -^ 3
_-.c.ti
' -"'^iT
fc.-T- •*•'
-'•it-d
4. XS,(»
; ;.. :c^
I 1 :' •k"'
vt
»-t
tl
l:'
*:'
•')
VHTD
1 ••• 1 4
1614
1614
1614
1614
1614
9979
9979
9979
9-779
9779
997?
2:.i*«
19115
i? :>..•;•
1. '. •» • •
.... .wo
iST-4?
1" C J V
•: • ."4 .•
. '..•-.•'. 7
:r, :"'-/
• « ' ^*
-•»'::•>
-•-4 si
2";: 4t-: d
1'795'V
I 7 1? •: 7
2 7 k"' 3 7
t*O'y 3
15779
2577?
61500
625t?tf
6.2500
*.15«t»
• .-2 '•#*}
6250fi
i.lVHTO
i?.7?
0.79
0.79
0.79
0.79
0.79
0 . 73
0.73
0.00
0.00
0.00
0.00
0.75
0.75
«!>. 75
,1 ~j f
* . i j
••i . 75
t? . 7'..
i? . ~ \
•?. 'I
".' . 7 )
i?. 71
M.71
w. 71
0.71
£.71
H.71
0.71
tl.71
•*.71
0.00
0.«0
0.kV
0.00
k'' . >-M
k'.'J'tf
UVMTn
0.00
0.7?
0.79
0.79
0.79
0.79
0.00
0.00
0.1*0
0.00
0.00
6.00
0.5*.
0.65
0.66
a, i
.66
0.67
0.67
v . '•• 9
!* . J9
>•'. 4t>l
0.41
0.43
0.43
0.37
0.41
0.41
0.42
0.43
0.43
0.13
0. 3
f. 3
0. 3
*. 3
tJ . 3
TEC
0.0000
0.9759
«.0460
0.1019
0.9410
0.0410
0.0000
0.0274
4. 043£
0.0440
0.0449
0.0440
0.0000
4.0274
0.0456
0.0 163
0.0440
0.0440
A A&&A
v • fr w
0.0274
0.*»45*.
0 . 0363
0.0440
0.0440
0 . *000
0.«74
0.0456
0.0369
0.0440
0.0440
0.0000
0.0009
0.0000
0 . 0600
IP . *li'k»H
0 . ttt't'tJ
TP8
0.0000
kl . 0000
0.046 . i$(>0
1 . tM*k>
CF
1 . * W0
0.3 .<£4
kl . 7t.0-»
0 . 7000
0.7000
0.7090
1.0000
1.0000
1.0000
1.0000
1.0000
1.0000
0.3280
0.6230
0.5700
c>aat*
. ^vww
.4500
.4500
.4000
.4200
.4000
.3500
.?-f 00
. 3000
.2300
.1110
0. 1250
0.0599
0.0000
0.0000
0.0000
0.0000
0.0000
0.0000
0.c4«>00
kl .IritltfU
------- |