77-18 FPH
An Evaluation of the Fuel Economy Performance
of Thirty-One 1977 Production Vehicles Relative
to Their Certification Vehicle Counterparts
January 1978
Technology Assessment and Evaluation Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Environmental Protection Agency
Prepared by: F. Peter Hutchins
James Kranig
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Introduction
The Environmental Protection Agency is conducting a number of studies to
identify the magnitude and causes of reported differences between the
fuel economies of in-use production vehicles and certification vehicles
as reported in the Mileage Guide.
The purpose of the study reported herein was to investigate through a
modest test program the magnitude of the differences (if any) in fuel
economy between production and certification vehicles when both types of
vehicles are tested at equivalent mileage (4000 miles) and state of tune
on the dynamometer using the standard Federal Test Procedure.
Eleven car models representing the fuel economy leaders of the 1977
subcompact class were selected for this study. Also, the fuel economy
leader within the individual manufacturer's specific car model was
generally selected. Thus, the program was experimentally directed
toward the highest fuel economy vehicles represented in the Mileage
Guide and was not designed to be representative of the wide range of
model offerings (and fuel economy) in the Guide.
Subcompact cars were selected because, with their greater fuel eco-
nomies, there was greater potential for detecting any differences in
production versus certification fuel economies. Three production cars
from each model were scheduled to be tested at EPA's Motor Vehicle
Emission Laboratory (MVEL) according to the 1977 certification testing
procedure.
Recognizing the experimental focus on higher fuel economy models and the
limited number of models selected, this program was intended to be only
a first step toward identifying differences (if any) between production
and certification vehicles and toward defining the need and basis for
similar programs in the future.
Summary of Findings
1) Despite low mileages, significant adjustments were required to
bring many of the vehicles to the proper state of tune as specified
in manufacturer's recommendations.
2) Since the idle quality of 26% of the vehicles (eight vehicles)
either remained poor or deteriorated after adjustment to manu-
facturer's specifications, adjustments to improve idle quality may
be made in the field which could adversely affect both emission and
fuel economy levels.
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-2-
3) After adjustment to manufacturers' specifications, most vehicles
met the 1977 emission standards by a wide margin although the
emission standards were exceeded by five vehicles for one pollutant
(Dodge Colt for HC, two Fiat. 128's for CO, one VW and one Gremlin
for NOx), one vehicle for two pollutants (Pontiac Sunbird for HC
and CO), and one vehicle for three pollutants (Dodge Colt).
4) Production vehicle fuel economies of the sub-compact class were
generally below certification levels with somewhat less than half
of the production vehicles being more than 10% lower than the
certification values.
5) The percent shortfall of production vehicles from certification
vehicle fuel economy was generally greater as the certification
fuel economy increased; conversely, the production vehicles in this
group that had the lower certification fuel economy values tended
to equal or exceed those values when tested in this program.
6) Test-to-test and vehicle-to-vehicle variability for each vehicle
and model were low and, therefore, do not explain the production to
certification fuel economy disparities.
7) The production vehicles with the largest shortfall, both as a
percentage and by absolute mpg, are the "fuel economy leaders" in
the Mileage Guide. This pattern is attributable only to the exist-
ence of a real difference between certification vehicles and pro-
duction vehicles.
8) Looking at country of origin, all of the vehicles (four out of 11
vehicle types tested) which exhibited the greatest shortfalls on
both the FTP and the HFET were imports from Japan (Honda, Datsun,
Toyota and Colt). However, these vehicle manufacturers are the
fuel economy leaders irrespective of whether the comparison is
based upon the Mileage Guide or the production vehicle results of
this program. All of the vehicles (VW, Ford 2.8L Pinto, Gremlin
2.0L) which either exceeded or equalled on average their counter-
part certification vehicle fuel economies were either manufactured
in Germany or were powered by engines built wholly or in part in
Germany. These vehicle types represented three of the 11 types
tested. Of the three domestic types tested, the Ford Pinto (2.3L
engine) exhibited the smallest shortfall followed by the Pontiac
Sunbird and the Chevrolet Chevette for the FTP. The Pontiac Sun-
bird had the smallest shortfall followed by the Ford Pinto (2.3L
engine) and Chevrolet Chevette for the HFET. The Chevette short-
fall was almost as large as the worst cases observed.
Conclusions
Analysis of the results from this study suggests that the fuel economy
performance of subcompact vehicles supplied to the EPA by the vehicle
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3
manufacturers for purposes of emissions certification and fuel economy
determination are not in all cases representative of the comparable
production vehicles. The small sample size for each vehicle specifica-
tion precludes an exact statistical quantification of the fuel economy
performance difference which exists. No extrapolation to other classes
of vehicles can be made from this study, nor would such an extrapolation
be appropriate, because in other studies EPA has found that, in general,
the prototype to production vehicle fuel economy shortfall is highest
for sub-compact vehicles.
The EPA cannot identify technological reasons which would explain the
high degree of fuel efficiency observed in the certification vehicles
which represent the fuel economy leaders in the Mileage Guide, nor
reasons which would explain the apparent lack of consistency of fuel
economy performance between the certification vehicles and their pro-
duction vehicle counterparts.
It is worth noting that no analogous pattern of discrepancies was found
for the emission characteristics of the in-use cars, which on the whole
handily met the emission standards applicable to them. This may suggest
that at least for the fuel economy leaders the basic certification
testing program, which is designed for determining the capability of a
vehicle complying with emission standards, may be more suitable for that
purpose than for precisely quantifying the fuel economy characteristics
of a model type. The testing program was not designed to quantify the
mean emission level of a model type, but rather to provide a high level
of assurance that the emission standard will not be exceeded. More
analysis is needed to determine if this program is or can be made to be
adequate for concurrently quantifying the mean fuel economy performance
of each model type.
The fuel economy values for vehicles listed in the mileage guide usually
represent the sales-weighted average fuel economy of several vehicle
configurations that were tested in EPA's emission certification and fuel
economy programs (e.g., data for four and five speed manual transmission
equipped vehicles were averaged in the 1977 Mileage Guide). The test
results from this study show that in many cases the production car
shortfall for the fuel economy leaders within the subcompact class was
even greater when the production car fuel economy was compared against
the fuel economy measured for the exactly comparable certification
vehicle rather than the sales weighted average fuel economy reported in
the Mileage Guide. Conversely the shortfall was usually less or non-
existent when the production cars representing lower fuel economies
(i.e. lower ranking) in the subcompact class were compared to their
exact certification configurations.
This suggests that the degree of precision provided by the average fuel
economy reported for each model in the Mileage Guide is being adversely
affected by the prototype vehicle configurations producing the highest
absolute fuel economies. Since only the high fuel economy configurations
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-4-
were generally tested in this study it is unknown what shortfall (if
any) would exist if the fuel economies of the production car configu-
rations were averaged and compared in the same manner as the certifi-
cation configurations. However, since this study found a sharply
decreasing shortfall trend with decreasing absolute fuel economy, it
may be concluded that the shortfall (if any) would be lower for the
comparison made on an average fuel economy basis. This latter con-
clusion is important since the primary purpose of the EPA fuel economy
program is to determine the sale-weighted corporate average fuel economy
(CAFE) for purposes of determining a manufacturer's compliance with fuel
economy standards under the Energy Policy and Conservation Act.
In view of the findings of this and other -studies, EPA is continuing to
study ways of improving the representativeness of the mileage guide fuel
economy values. This will include continued study of all possible
causes of the discrepancies identified in this test program to help EPA
assure that prototype vehicles are fully representative of production
cars and to study different methodologies for collection and dissemi-
nation of fuel economy information for consumer purposes. .
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-5-
Test Procedure
The eleven 1977 vehicle models selected for testing are briefly des-
cribed in Table 1. Appendix I contains detailed vehicle descriptions.
Two vehicles representing each model were obtained by a contractor from
private owners in the Southeastern Michigan area and delivered to MVEL
for testing. The vehicles so obtained were required to have between
3,500 and 8,000 miles of owner-accumulated mileage. The owner was
requested to sign a statement which established that the vehicle emis-
sion controls had not been tampered with and that the correct fuel had
been used.
In addition to the two privately-owned vehicles supplied for each model,
the manufacturers of each respective model were invited to supply a
third representative vehicle. The manufacturers were also invited to
participate in the check-in inspection of all of their products and
generally did so.
Table 1
General Vehicle Descriptions
Model
Year
1977
1977
1977
1977
1977
1977
1977
1977
1977
1977
1977
Model
AMC Gremlin
Chevrolet Chevette
Datsun B210
Dodge Colt
Fiat 128
Ford Pinto
Ford Pinto Wagon
Honda Civic CVCC
Pontiac Sunbird
Toyota Corolla
VW Rabbit
Engine
2.0L
1.6L
1.6L
1.6L
1.3L
2.3L
2.8L
1.5L
2.5L
1.2L
1.6L
Transmission
Manual-4 or
Automatic-3
Manual-4
Manual- 5
Manual-4
Manual-4
Manual-4
Automatic-3
Manual- 5
Manual-4
Manual-4/5
Manual-4
Final Drive Ratio
3.31:1
3.70:1
3.70:1
3.31:1, 3.54:1, 3.89:1
3.76:1
2.73:1
3.00:1
3.88:1
2.74:1, 2.93:1
3.91:1, 4.10:1
3.90:1
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-6-
The check-in inspection was conducted to ensure that the vehicles were
as similar as possible to their certification vehicle counterparts,
i.e., that each vehicle had: 1) a leak-free exhaust system, 2) was
manufactured with the proper components, 3) had all emission control
equipment properly installed and functioning, and 4) was tuned to
specification. The items checked varied from vehicle to vehicle but in
general included those listed in Table 2. Adjustable items were set to
nominal values as recommended by the manufacturers in their service
literature or instructions. The fuel tank was emptied and filled with
the type of gasoline used in the 1977 certification testing.
Table 2
Typical Parameters Checked During Vehicle Inspection
Exhaust system integrity
Driven wheel brake drag
Axle ratio
Vehicle curb weight
Ignition timing
Ignition dwell
Full spark advance
Spark trace pattern
Fast idle rpm
Curb idle rpm
Idle CO percent and/or other idle mixture measurements
Idle quality
Spark plug condition and gap
Cranking compression
Battery fluid level
Engine oil level
Transmission fluid level
Differential fluid level
Coolant level
Air filter condition
Valve adjustment
Following the check-in procedure, the vehicles were given an initial
preconditioning consisting of three EPA urban dynamometer driving
schedules (UDDS) prior to the normal UDDS prep cycle. The initial
preconditioning was implemented to assure that the evaporative canisters
were adequately purged. The testing of each vehicle consisted of three
'77 Federal Test Procedures (FTP) and three Highway Fuel Economy Tests
(HFET). Two FTPs and two HFETs were conducted on one dynamometer by the
same driver for all vehicles. The third FTP and HFET were conducted on
another dynamometer by other drivers. This was intended to give some
indication of the repeatability of the vehicle and variations induced by
alternate driver/dynamometer combinations. At the completion of testing
the vehicles were again checked to verify that they were still properly
tuned, etc.
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-7-
Discussion and Results
The check-in procedure for all of the vehicles was detailed and required
an average of three hours per vehicle. Nearly all vehicles required
some adjustments. Nine vehicles had exhaust systems with leaks severe
enough to require correction. Several manufacturers requested to have
the valve lash checked and adjusted. The individual vehicle adjustments
are summarized in Table 3.
Despite the fact that these were new, low mileage vehicles which sup-
posedly had not been maladjusted or tampered with, many required con-
siderable adjustment to bring them to manufacturers' specification.
Five vehicles exhibited poor idle quality as received. The idle quality
of eight vehicles either deteriorated as a consequence of adjustment to
specifications or remained poor despite adjustment. Poor idle conditions
resulting from adjustment to specifications may lead to subsequent
adjustments to other than specified settings which could increase emis-
sions and decrease fuel economy. If the vehicles had been tested before
tuning, many would undoubtedly have shown higher emissions and poorer
fuel economy. Such testing was not a part of this program, because the
testing of as-received vehicles has been adequately covered in other EPA
surveillance programs.
The measured emission levels of the vehicles over the FTP are given (the
mean of the results of 3 tests of each vehicle) in Appendix II as
average values. To compare these emission levels to the 1977 Federal
emission standards of 1.5, 15, and 2.0 grams per mile of HC, CO, and
NOx, the measured values are multiplied by the applicable deterioration
factors determined from certification for each engine family. For the
vehicles tested at more than 4,000 miles, the certification deteriora-
tion factors used to project 50,000 miles values were adjusted accord-
ingly. This yields the projected 50,000 mile emission levels for each
vehicle. Appendix II also presents these projected emission levels.
Figure 1 contains plots of these projected emission values. As can be
seen the vehicles were, for the most part, meeting the emission stan-
dards, many by a wide margin. Those exceeding the standard in one or
more of the three pollutants tended to fail by a small margin. Only one
vehicle failed all three pollutant levels.
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Table 3
Summary of Pre-Test Adjustments
Vehicle (I.D.) Timing
Chevette (038)
Chevette (084)
Chevette (065)
Colt (382) X
Colt (452)
Colt (943)
Datsun (746)
Datsun (360)
Datsun (411) X
Fiat (199) X
Fiat (322) X
Fiat (659) X
Gremlin (317)
Gremlin (693)
Gremlin (587) X
Honda (166) X
Honda (GM) (087)
Honda (Honda) (458)
Pinto 2.3L (495) X
Pinto 2.3L (742) X
Pinto 2.3L (930) X
Pinto 2.8L (330)
Pinto 2.8L (162)
Sunbird (762) X
Sunbird (720) X
Corolla (075)
Corolla (331)
Corolla (096) X
Rabbit (310) X
Rabbit (162)
Rabbit (532)
a - Throttle dash pot
b - Fuel shut-off system
c - Belt tension
d - Throttle linkage
e - Coolant
f - Clutch
x - Adjustment performed
Idle
Speed
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Idle
Mixture
X
X
X
X
X
X
X
X
X
1
Exhaust Oil Valve
Leak Fixed Added Lash
X X
X XX
X X
X
X
X
X
X
X X
X
X
X
- X
X
X
X
X
Spark
Plug Brake
Gap Drag
X
X
X
X
X
Idle Quality
Other Initial Adjusted
X
X
X
X
fair
fair
poor
good
fair
a, b good
a, b
good
good
good
poor
c, d good
poor
good
good
fair
e poor
fair
poor
fair
good
fair
good
good
good
good
poor
poor
poor
good
good
fair
fair
good
good
good
poor
good
poor
good
good
fair
fair
good
fair,
good"
good
fair
good
good
good
i
00
1
1 - Was determined to be overly rich after testing
GM initially declined adjustment prior to test.
2 - Spark plug broken at inspection & replaced.
3 - Sunbird (762) idle condition deteriorated to
poor after idle mixture adjustment. It resulted
in a very rough idle condition with severe
engine rock.
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NOx Emissions (grams/mi) CO Emissions (grams/mi) HC Emissions (grams/mi)
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The fuel economy results are plotted in Figures 2 and 3. It can be seen
that the production vehicles generally fell well below their certifi-
cation vehicle counterparts. Also, nearly 40% of the vehicles achieved
less than 90% of the certification value. These results are given in
detail as tables in Appendix III. For each vehicle the measured fuel
economies over the FTP and HFET are shown for each test as well as the
mean and the standard deviation as a percent of the mean. The certifi-
cation vehicle fuel economies obtained by EPA and by the manufacturer,
as well as the fuel economy reported in the Mileage Guide are listed in
the left columns of the appendix tables. In the right columns, the
production vehicle fuel economies are shown as a., percent of both the EPA
Certification value and the mileage guide value.
Another method of analyzing the fuel economy results is to look at the
relative fuel economy ranking of the vehicles (see Table 4). Comparison
of the FTP certification and production vehicle fuel economies shows
that VW Rabbit moved from a ranking of twelfth in certification to
eighth in production, thereby moving ahead of the two calibrations of
2.3L Pintos, one of the Pontiac Sunbirds, and the Colt station wagon.
Similarly, comparing the HFET certification and production vehicle fuel
economies shows that the Rabbit moved from tenth to seventh by moving
ahead of the 2.3L Pintos and one of the Pontiac Sunbirds. The Gremlin
with the manual transmission advanced from thirteenth to eleventh passing
one 2.3L Pinto and Fiat.
The 2.8L Pinto station wagons are not really in the mileage leader class
as are the remainder of the vehicles tested. The 2.8L Pintos did achieve
the largest percentage improvement in fuel economy when comparing pro-
duction and certification vehicles for the FTP (8..7 and 8.4%) and for
the HFET the 2.8L Pintos (7.0 and 4.8%) were second only to the Gremlin
manual (8.5%). It is possible that these increases would have advanced
the 2.8L Pinto in a ranking of vehicles of comparable fuel economies.
Comparable fuel economy vehicles were not tested in this program.
There are several reasons why the Mileage Guide and the EPA Certifi-
cation values may differ. The more important are: 1) that a number of
engine calibrations, each with its own certification value, may be
combined to yield the Mileage Guide value, 2) manual 3, 4 and/or 5
speed vehicle fuel economies are combined, and 3) Mileage Guide values
are rounded to the nearest whole numbers.
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Figure 2
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Table 4
Ranking of the Vehicles Tested in Order of Decreasing Fuel Economy
Mileage
Guide
1-Honda
2-Datsun
3-Toyota M5
3-Toyota M4
5-Chevette
6-Colt sdn.
7-Pinto 2.3 (1)*
7-Pinto 2.3 (2)*
7-Sunbird (1)**
7-Sunbird (2)**
11-Colt SW
11-Rabbit
13-Fiat
14-Gremlin M
14-Gremlin A
16-Pinto 2.8 SW*
16-Pinto 2.8 SW*
FTP
Certification
Vehicle
1-Honda
2-Datsun
3-Toyota M5
4-Toyota M4
5-Chevette
6-Colt sdn.
7-Sunbird (1)
8-Pinto 2.3 (1)
9-Sunbird (2)
10-Pinto 2.3 (2)
11-Colt SW
12-Rabbit
13-Fiat
14-Gremlin M
15-Gremlin A
16-Pinto 2.8 SW (1)
17-Pinto 2. 8 SW (2)
Production
Vehicles
1-Honda
2-Toyota M4
3-Toyota M5
4-Datsun
5-Chevette
6-Colt sdn.
7-Sunbird (1)**
8-Rabbit
9-Pinto 2.3 (1)
10-Colt SW
11-Sunbird (2)**
12-Pinto 2.3 (2)
13-Gremline M
14-Fiat
15-Gremlin A
16-Pinto 2.8 SW (1)
17-Pinto 2.8 SW (2)
Mileage
Guide
1-Honda
2-Datsun
3-Toyota K5
3-Toyota M4
5-Colt sdn.
6-Chevette
7-Colt SW
7-Pinto 2.3 (1)
7-Pinto 2.3 (2)
7-Rabbit
7-Sunbird (1)
7-Sunbird (2)
13-Fiat
14-Gremlin M
15-Gremlin A
16-Pinto 2.8 SW (1)
16-Pinto 2.8 SW (2)
HFET
Certification
Vehicle
1-Honda
2-Datsun
3-Toyota M5
4-Toyota M4
5-Colt sdn.
6-Chevette
7-Sunbird (1)
8-Pinto 2.3 (1)
9-Pinto 2.3 (2)
10-Rabbit
11-Colt SW
11-Sunbird (2)
13-Fiat
14-Gremlin M
15-Gremlin A
16-Pinto 2.8 SW (1)
17-Pinto 2.8 SW (2)
Production
Vehicles
1-Honda
2-Datsun
3-Toyota M5
4-Colt sdn.
5-Toyota M4
6-Chevette
7-Rabbit
8-Sunbird (1)
9-Pinto 2.3 (1)
10-Colt SW
11-Sunbird (2)
12 -Gremlin M
13-Pinto 2.3 (2)
14-Fiat
15-Gremlin A
16-Pinto 2.8 SW (2)
17-Pinto 2.8 SW (1)
*
**
Separated by calibrations.
Separated by axle ratios.
(1) , (2) Represent different calibrations and are included
to identify changes in ranking in the calibrations.
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-14-
Still another way of looking at the fuel economy results is to examine
the absolute fuel economy differences between ranked vehicles. Figure
4 clearly shows that the range of fuel economies from the Mileage Guide
is significantly larger than that found for the production vehicles
(i.e. the difference between the highest and lowest fuel economy models).
A buyer weighing the various vehicle choices may use as one factor the
expected relative difference between several vehicle fuel economies
shown in the Mileage Guide. If this buyer were considering buying
either a Honda or a Rabbit, for example, the buyer would find that the
Mileage Guide indicates that the Honda would provide a fuel economy ad-
vantage over the Rabbit of 67% for the FTP and 40% for the HFET. The
production vehicles tested showed these advantages would be only 41% for
the FTP and 21% for the HFET. Thus it appears that the Mileage Guide
exaggerates fuel economy differences between ranked vehicles in compari-
son to actual production car fuel economy differences.
MPG 0 10 20 30 40 50 60
O O Mileage Guide
FTP O O Production
O O Mileage Guide
HFET O O Production
Figure 4
Absolute Range of Fuel Economies
Between Lowest and Highest Fuel Economy Models
Comparison of the harmonic average fuel economies of the test fleet
for the FTP and the HFET with the same averages from the comparable
certification vehicle fleet showed a 2.7% shortfall on the FTP and a
3.8% shortfall for the HFET. These shortfalls are significantly lower
than the worst cases observed and suggests that the existing fuel
economy determination procedures are fairly accurate with respect to
fleet averages; e.g. Corporate Average Fuel Economy.
Possible Causes for the Observed Disparities
Many factors, either singly or in combination, can be identified as
potential causes of the observed disparity between the production
vehicle and certification vehicle fuel economy. These factors are: 1)
differences in the way mileage is accumulated between production and
certification vehicles, 2) differences in tires and their interaction
with the dynamometer, 3) systematic lab error/shift, 4) differences in
vehicle maintenance procedures, 5) test-to-test variability, 6) vehicle-
to-vehicle variability, 7) small test sample size, and 8) significant
differences between certification and production vehicles.
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-15-
Each of these possible causes is discussed below:
1) Mileage accumulation for the certification vehicles is accomplished
on a specified durability driving schedule. One cycle consists of
11 laps over a 3.7 mile course. The basic vehicle speeds for each
consecutive lap are 40, 30, 40, 40, 35, 30, 35, 45, 35, 55 and 70
mph. Each of the first nine laps contains four stops of 15 seconds
each, normal accelerations and decelerations, and five light decel-
erations from base speed to 20 mph followed by light acceleration
back to base speed. The tenth lap is a, constant 55 mph. The llth
lap is begun with a wide open throttle acceleration from 0 mph to
70 mph. A normal deceleration to idle is followed by a second wide
open throttle acceleration. For the emission and fuel economy data
vehicles, this cycle is repeated until a total of approximately
4000 vehicle miles is accumulated with the vehicle at approximately
curb weight. This procedure results in nearly continuous operation
with few cold starts relative to normal on-the-road driving.
In contrast, the production vehicle mileage accumulation process
can be widely varied. There was no way to accurately ascertain the
type of operation that each vehicle was subjected to. It is con-
ceivable that the vehicles could have been primarily used for short
trips, mid-range commuting, long trips, or any combination of
these. It is expected, however, that the vehicle operation would
not be continuous and would involve numerous overnight soaks fol-
lowed by cold starts. Additionally, the total vehicle weight at
which much of the mileage was accumulated could vary from a base
weight including only the driver to maximum weight including full
passenger, luggage and trailer towing capacities. The total miles
accumulated on the test vehicles ranged from 3200 to 8800 miles.
However, in order for differences in mileage accumulation procedures
to be given credence as a significant cause of the observed disparity
between production and certification vehicle fuel economy, one
would need to conclude that all production vehicles within each
model were operated very similarly because of the small differences
observed in the production vehicles; e.g. all production Datsun B-
210's were operated in such a way as to cause the large observed
shortfall in fuel economy while all VW Rabbits were operated in
such a way as to cause the observed overage in fuel economy. The
observed shortfalls cannot, therefore, be attributable to dif-
ferences between mileage accumulation procedures.
2) Variations in production tires and the associated changes in the
tire/dynamometer interface can cause significant differences in
fuel economy results. Previous testing has shown that rolling
-------
-16-
resistance can vary significantly both on the road and on the
dynamometer and depends upon tire rubber composition, size, manu-
facturer, type of construction and/or model of tire. The pro-
duction vehicles tested in this project were equipped with a wide
range of tires which differed by manufacturer, size and type of
construction. Inspection of the data failed to identify any trends
which could be attributable to the production tires. If the obser-
ved differences between certification and production vehicle fuel
economy is attributable to tires, one would need to conclude that
the tires used on the certification vehicles were not representative
of normal production tires. Data does not exist which would allow
comparison of the performance of tires used on certification vehicles
with comparable production tires. One cannot conclude at this
time, therefore, whether or not the tires used on certification
vehicles are the cause of the observed differences between pro-
duction and certification vehicles.
3) A systematic shift in test results may exist due to some unknown
change in the test facility and/or procedure since the 1977 certi-
fication vehicles were tested. On-going MVEL quality control pro-
grams have shown a systematic downward shift in fuel economy results
of about one to two percent. This shift is believed to be due to
an increase in the relative humidity during testing. However, this
downward shift (1 to 2%) is too small to account for the observed
large scale shortfalls (up to 15%). Additionally, if this shift is
to be used to explain some of the shortfall then it must also be
credited to those vehicles achieving overages. Thus, the dif-
ference between maximum percent shortfall and maximum percent
overage remains at about 24%.
4) Differences in maintenance history is another possible cause of the
fuel economy disparities. While certification vehicle maintenance
is well controlled and monitored, production vehicle maintenance
varies with each owner. There have been investigations which show
that better maintenance generally implies better fuel economy.
However, the effect of maintenance does not appear to be a signi-
ficant factor in this study because some vehicles with meticulous
service records exhibited large shortfalls while others which were
found to be poorly maintained, e.g., nearly two quarts low on oil
when delivered to EPA, exhibited a small shortfall. Additionally,
within each make, poorly maintained vehicles did no worse than
their better maintained counterparts.
5) Test-to-test variation has been indicated as a possible cause of
the fuel economy disparities. This is a combination of laboratory
testing variations, variability due to drivers, and variability due
-------
-17-
to dynamometers. However, only three drivers and two dynamometers
were used in this project and generally each vehicle was tested by
two drivers and on two dynamometers so any trend would be applicable
to all vehicles. A trend was not noted. The standard deviations
(variation in each test point expressed as a percent of the mean)
were small for most vehicles with only two vehicles exceeding 2.5%
for the FTP and three vehicles for the HFET (see Appendix III).
6) Vehicle-to-vehicle variation can be due to differences in tires,
maintenance, mileage accumulation, normal production tolerances,
and limits in the accuracy of tuning the parameters affecting fuel
economy. Within each vehicle group (vehicles with same model,
engine calibration, and driveline) variations between vehicles were
small (see Appendix IV).
In Appendix IV, variations between vehicles are expressed as the
range of. individual vehicle means divided by the mean of all vehi-
cles within the group. In no case did any vehicle group exceed 10%
variation for either the FTP or the HFET (single vehicle groupings
resulting from calibration and axle ratio differences were excluded
so as not to bias the results toward lower variations). The average
variation for the eight groups was 5.86% for the FTP and 3.71% for
the HFET.
This observed low variability within vehicle groups persists even
when a similar comparison is made between the range of all tests
performed on vehicles within a group relative to the mean of the
group; i.e. when test-to-test and vehicle-to-vehicle differences
are combined (see Appendix V). In this case, it was found that
only three groups exceeded 10% variation for the FTP and the HFET.
The average variation for all groups was 5.23% for the FTP and
5.29% for the HFET. Excluding single vehicles where there is no
vehicle-tor-vehicle variation for the group resulted in average
variations of 8.02% for the FTP and 7.38% for the HFET.
Additionally, it must be noted that in no case where there is a
significant production vehicle fuel economy shortfall for a vehicle
group does any one of the vehicles approach or exceed the certifi-
cation vehicle fuel economy.
It should also be noted that the observed high degree of consis-
tancy between vehicles was also exhibited in the emissions results
(refer to Figure 1).
7) The small sample size prevents the determination of the statistical
significance of the results (i.e., it cannot be determined, statis-
tically, whether there is a real difference between the production
-------
-18-
vehicles and the certification vehicles regarding fuel economy or
whether the disparity is due to a biased sample). It is worthy of
note, however, that the sample size for certification vehicles is
usually even smaller (one vehicle) than the sample size used in
this production vehicle evaluation project. The small sample size
prevents determination of whether some or all of the sample vehicles
were or were not representative of the actual production vehicle
population for the specific groups. However, the generally small
variations among the vehicles within the various groups suggests
that the normal production variations tend to be small for these
models. This in turn suggests that these sample groups were
reasonably good approximations for the purposes of the test pro-
gram, given the small magnitudes of variations among vehicles
relative to the magnitudes of disparities found between certifi-
cation and production vehicle fuel economies.
8) The remaining factor which could cause the disparity between
certification and production vehicle fuel economies is the exist-
ence of a real difference between the production and certification
vehicles. The production vehicle check-in was similar to that used
with certification vehicles and was limited in scope to "external
vehicle checks", i.e. no disassembly for inspection of internal
parts. No specific item(s) or parameter(s) capable of causing fuel
economy changes were noted, however. Nevertheless, the absence of
specific evidence of differences cannot be construed as evidence of
the absence of differences.
In plotting the data, a pattern of deviation by production vehicles
from certification vehicle fuel economies emerges. Plotting the
vehicle fuel economies in order of decreasing certification fuel
economy (Figures 5 and 6) points out that the largest discrepancies
between production vehicle and certification vehicle fuel economy
values occur where the vehicles have certification FTP values above
25 mpg and HFET values above 40 mpg. Conversely, the only instances
where the production vehicle fuel economy exceeds the certification
vehicle fuel economy are where the FTP and HFET values are below 25
and 40 mpg, respectively. This pattern of disparities is further
exemplified by plotting the percent deviation of production vehicle
fuel economy from certification vehicle fuel economy in order of
decreasing shortfall by models (Figures 7 and 8). The disparities
are detailed in Appendix VI. By comparing the figures, it can be
seen that the "fuel economy leaders" tend to have the largest
absolute and percentage shortfalls of production versus certi-
fication vehic.le fuel economy.
-------
-19-
T*
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of Decreasing EPA Certification Fuel Economy
Figure 5
-------
-20-
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Vehicle Model
HFET Fuel Economy by Model in Order of
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Figure 6
-------
Figure 7
Percent Deviation of Production Vehicle Fuel Economy from Certification Vehicle
IBI
7.0
% H.0
o ro
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-17
-20
Fuel Econo
. Production MPG
. Greater than
. Certification MPG
. Production MPG
. Less than ^
. Certification MPG
-
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-------
Figure 8
Percent Deviation of Production Vehicle Fuel Economy from Certification Vehicle
IU
7.0
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-17
-20
Fuel Economy (in order or decreasing
r- HFET
Production MPG
. greater than
Certification MPG
"
.
Production MPG
. less than
. Certification MPG M
BB
X
xx
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n
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-------
-23-
It is important to note the probable pattern of the occurrence of
the various possible causes identified. Mileage accumulation
differences, tire-to-dynamometer interface effects (most manu-
facturers have multiple suppliers for tires and tire types vary
extensively, e.g. bias and radial are used interchangeably in
production), and maintenance effects would generally occur randomly
in the sample of the vehicles. The systematic lab shift, the test-
to-test variability, and the small sample problem would generally
be applied to all vehicles. Therefore, the only causes which would
be expected to be associated to specific model groups would be
vehicle-to-vehicle variability and significant differences between
certification and production vehicles. However, vehicle-to-vehicle
differences were observed to be small. The only plausible explana-
tion is, therefore, that significant differences do exist between
production and certification vehicles.
-------
Append ix 1
:!'!;;;:; is X'n.i-1 'i'e.ir
1977 AMC Gremlin
.'; ii'nl) il L Lv W.:u;::ui:!: <-J
( infiii'::'i tiv'ii i:- Lilt-iK i .:.'t I lu
i . - A7M4646722317
4 stroke Otto cycle, OHC, 1-4
86.5 x 84.4 mm/3.405 x 3.323 in.
I 2.0L/121 cu. in.
1 8.1:1
Single 2 venturi carburetor
1 Unleaded regular
Manual 4 speed
3.31:1
Front enginer , rear wheel drive
1)78-1.4, bias, Goodyear
2550 ib. (w/ 1/4 tank)
3000 Ib.
four
Evap., air, EGR, catalyst
Breaker points
6600 mi.
'.'IN - A7A464G723693
Automatic
D78-14, bias, Goodyear
2606 Ib. (w/ 3/16 tank)
6900 mi.
VIN - A7C465K706587
Automatic
CR78-14, radial, Goodyear ^
7300 mi.
-------
Appendix I
Chassis Model Year/Make
1977 Chevrolet Chevette
Engine Calibration .
Type
Bore >; Stroke
Displacement
Compression Ratio ..
Max iiTium Power @ rpm
Fuel Metering
Kuisl Ku'juirenent . . .
Drive Train
Transmission Type
Final Drive Ratio
Chassis
Type
lire Size
Curb Weight
Inertia Weight ....
Passenger Capacity
Enission Control System
Basic Type
Ignition System
Durability Accumulated
on System
(Information is identical to
first vehicle listed excent
as noted.)
- 1B08E7Y188038
710W1 AB
4 stroke Otto cycle, OHC, 1-4
82.0 x 75.7 mm/3.228 x 2.900 in.
1.6L/97.6 cu. in.
8.5:1
Single 1 venturi carburetor
Unleaded regular
Manual 4 speed
3.70:1
Front engine, rear wheel drive
P155/80D-13, 4 ply bias, Uniroyal
2070 Ib. (w/ 5/8 tank)
2250 Ib.
four
EM, EGR, Catalyst, PCV, thermosta-
tically controlled air cleaner, evap.
Electronic
4800 mi.
VIN - 1B08E7Y155084
VIN - 1B08E7Y109065
P155/80R-13, radial, B. F. Goodrich
2020 Ib. (w/ 1/2 tank)
4900 mi.
i
to
P155/80D-13, bias, Goodyear
7800 mi.
-------
ix T
Chassis Model Year/Ma I-;.1
1977 Datsun B210 +
'In:; i \ie
Engine Calibration . . . . ,
~.j. re x Stroke
J is j) j..icei!;eii t
Compression Ratio ..
Xa::irmn Power .? rpm
P:e j. Me! tor ing
':'i:ei Ke.oui ri.-i.iun t . . .
Drive Tram
Transmission Type
Final Drive Ratio
Chassis
j p e
i ire Size
Curb Weight
Inertia Weight
Passenger Capacity
r.:-.ission Control SvsLe;:;
Basic Type
I~ni t ion SYS ten
Durab ii ity Accur.iulated
or. S'.-ster;
(Information is identical to
first vehicle listed excfa
as noted.)
Vi:; - HLB210-222360
A141F
4 stroke Otto cycle, OHV, 1-4
76.0 x 77.0 nun/2.992 x 3.031 in.
1.4L/85.24 cu. in.
8.5:1
Single 2 venturi carburetor
Unleaded regular
Manual 5 speed
3.70:1
Front engine, rear wheel drive
155SR-13, radial, Yokohama
2060 Ib. (w/ full tank)
2250 Ib.
four
Catalyst, evap. , EGR, EFE, Air.
Breaker points
4700 mi.
VIN - DHLB210202411
VIN - HLB210208746
155SR-13, radial, Dunlop
2035 Ib. (w/ no fuel)
4200 mi.
i
NJ
155SR-13, radial, Dunlop
2060 Ib. (w/ 7/8 tank)
4700 mi.
-------
Appendix I
Chassis Model Year/Make
1977 Dodge Colt
Engine
Engine Calibration .
Type
Bore x Stroke
Displacement
Compression Ratio . .
Maximum Power @ rpm
Fuel Metering
Fuel Requirement . ..
Drive Train
Transmission Type
Final Drive Ratio
Chassis
lire S Lze
Curb Weight
Inertia Weight
Passenger Capacity
Emission Control System
Basic Type
Iznition System
Durability Accumulated
on System
(Information is identical to
first vehicle listed excc-^t
as noted.)
VI:. - 6H45K75115452 (SW)
4G32
4 stroke Otto cycle, OHC, 1-4
77.0 x 86.1 mm/3.03 x 3.39 in.
1.6L/97.5 cu. in.
8.5
Single 2 venturi carburetor
Regular
Manual 4 speed
3.89:1
Front engine, rear wheel.drive
165SR-13, radial, Firestone
2392 Ib. (w/ 1/8 tank)
2750 Ib.
four
Evap. , EGR, AIR, PCV
Breaker points
4800 mi.
VIN - 6H41K74201943 (Sedan)
VIN - 6M21K71102382 (Sedan)
3.54:1
155 SR-13, radial, B. F. Goodrich
2120 Ib. (w/ 3/4 tank)
2250 Ib.
3800 mi.
3.31:1
6.00-13, bias, B. F. Goodrich
2250 Ib.
8800
-------
Append ix I
Chassis Nodel Year/Make
1977 Fiat 128 Sedan
Engine Calibration .
Type
Bore :: Stroke
Displacement
Compression Ratio ..
Maximum Power @ rpm
Fuel Metering
'fuel Kunti ironiiriiL ...
Drive Train
Transmission Type
Final Drive Ratio
Chassis
iire Size ,
Curb Weight ,
Inertia Weight ...
Passenger Capacity
Emission Control System
Basic Type
Ignition Svstem
Durability Accumulated
on System
(Information is identical to
first vehicle listed exci'H
as noted.)
VI:: - 128A12314199
EF128
4 stroke Otto cycle, OHC, 1-4
86 x 55.5 mm/3.39 x 2.19 in.
1290 cc/78.70 cu. in.
8.5:1
62 HP
Single 2 venturi carburetor
Unleaded regular
Manual 4 speed
3.76:1
Front engine, front wheel drive
145SR13, radial, Michelin
1980 Ib. (w/ 3/4 tank)
2250 Ib.
four
EM, evap., catalyst, air, EFE
Breaker points
3200 mi.
VIN - 128A12395322
- 128A12B70659
145SR13, radial, Michelin
3400 mi.
ho
oo
145SR13, radial, Pirelli Cinturato
1900 Ib. (w/ 3/4 tank)
4100 mi.
-------
Appendix I
Chassis Model Year/Make
1977 Pinto 2.3L
Engine
Engine Calibration .
Type
Bore x Stroke
Di.-;p.l.icun.cn;:
Compression Ratio ..
Maximum Power Q rpm
Fuel Meter ing
Fuel Kequ irer.ient . . .
Drive Tra_l:n
Transmission Type
Final Drive Ratio
Chassis
lire Si ze
Curb Weight
Inertia Weight
Passenger Capacity ....
En Lssion Co n t r o 1 System
Basic Type
Ignition System
Durability Accumulated
on bystem
(Information is identical to
first vehicle listed exeunt
as noted.)
F7X11Y187495
7-2B-RO
4 stroke Otto cycle, OHC, 1-4
96.0 x 79.4 mm/3.78 x 3.126 in.
2.3L/140 cu. in.
Single 2 venturi carburetor
Unleaded regular
Manual 4 speed
2.73:1
?ront engine, rear wheel drive
A78 x 13, bias, Goodyear
2500 Ib. (w/ no fuel)
2750 Ib.
four
EM, EGR, catalyst, PCV, air
Electronic
5500 mi.
VIN - F7771Y115742
7-2B-RO
A78 x 13, bias-belted, Firestone
2580 Ib. (w/ 3/8 tank)
7600 mi.
VIN - F7X11Y185930
7-2A-R13
N)
VO
BR78 x 13, radial, Goodyear
2480 Ib. (w/ 1/3 tank)
6800 mi.
-------
Appendix I
Chassis Model Year/Make
1977 Pinto 2.8L Station Wagon
Engine Calibration
Stroke
Compression Ratio ..
M;'.xi::iu.i>. Power 0 rpm
Fuel Mote r in;; ......
Fuel i\e
o
I
6000 mi.
-------
Append ixI
Chiles is Model Year/Mai-
Honda
c.n:; me
Engine Calibration
.-pe
Jiore :; Stroke
J i.:p li.o-i.cLruL
Corpr^s.s Ic'n Ratio ..
'I.';:-: iniun Pii'.vV.r c- rpm
Fuel .\elering
''!-jj <>euu i renien t . . .
_Dr_rye_ Trajn
Trans;:; iss ion Type
Final Dr ive Rat Lo
Chassis
lype
1 ire Size
Curb Weight
Inert ia Weight . . . .
Passenger Capacity
E:~:issi'Mi Control S\
I en it ion Svsti-n
Durability Accumulated
on Svstera
(Infornacion is identical to
first vehicle listed except
as no ted.)
VI.\ - SGE3508458 (Honda)
4 stroke Otto cycle, OHV, 1-4
74.0 x 86.5 mm/2.91 x 3.41 in.
1.5L/90.8 cu. in.
7.9:1
60 HP
Single 3 venturi carburetor
Unleaded regular
tonual 5 speed
3.88:1
Front engine, front wheel drive
600-S12, bias, Bridgestone
1880 Ib.
2000 Ib.
four
Stratified charge.
Breaker points
3300 mi.
VIN - SGE-3001087 (GM)
VIN - SGE-3511166 (Canadian)
600-S12, bias, Bridgestone
1790 Ib.
5500 mi.
155-SR12, radial, B. F. Goodrich
1765 Ib. (w/ full tank)
7300 mi.
-------
Appendix I
Chassis Model Year/Hake
1977 Pontiac Sunbird Sedan
Engine Calibration .
Type
Bore x Stroke
ji-; pi;; cement
Compression Ratio ..
Maximum Power @ rpm
Fuel Me Ler ing
l-'uiiL Ki'qu irement ...
jnve Ira in
Transmission Type
Final Drive Ratio
Chassis
Type
lire Size
Curb Weight
Inertia Weight
Passenger Capacity
Hr.ission Control System
sic Type
Isnition System
Durability Accumulated
or. System
(information is identical to
first vehicle listed OXL-^C
as noted.)
2M27V72332762
710C2-F
4 stroke Otto cycle, OHV, 1-4
101.6 -x. 76.2 nun/4.00 x 3.00 in.
2.5L/151 cu. in.
8.25:1
Single 2 venturi carburetor
Unleaded regular
Manual 4 speed
2.93:1
Front engine, rear wheel drive
BR78 x 13, radial, Uniroyal
2810 Ib. (w/ 1/2 tank)
3000 Ib.
four
EM, EGR, catalyst, PCV, evap., EFE
Electronic
3600 mi.
VI.N - 2M27V72340720
VIN -
2.74:1
BR78 x 13, radial, Uniroyal
2800 Ib. (w/ 1/4 tank)
i
10
7600 mi.
-------
Chassis Model Year/Make
1977 Toyota Corolla
Engine
Engine Calibration
Bore x Stroke
Di -olaeemunt
Compression Ratio ..
Maximum Power @ rpm
Fuel Metering
Fu^l Requirement . ..
Drive Train
Transmission Type
Final Drive Ratio
Chassis
lire Size
Curb Weight
Inertia Weight ....
Passenger Capacity
Emission Control Svstem
Basic Type
Ignition Svstem
Durability Accumulated
on System
(Information is identical to
first vehicle listed exci-^t
as noted.)
VIN - KE30178075
3K-C
4 stroke Otto cycle, OHV, 1-4
75.0 x 66.0 mm/2.95 x 2.60 in.
1.2L/71.15 cu. in.
9.0:1
58 HP @ 5800 rpm
Single 2 venturi carburetor
Unleaded regular
Manual 4 speed
3.91:1
Front engine, rear wheel drive
'155S-13, bias, Dunlop
1930 Ib. (w/ 1/8 tank)
2250 Ib.
four
Catalyst, Air PCV, evap., fuel shut-
off, mixture control valve
Breaker points
5800 mi.
VIN - KE30169331
VIN - KE30224096
155S-13, bias, Dunlop
1975 Ib. (w/ 3/4 tank)
7400 mi.
Manual 5 speed
i
CO
U)
155SR-13, radial, Dunlop
2020 Ib. (w/ full tank)
4300 mi.
-------
Ch-.issis Model Year/Make
1977 Volkswagen Rabbit
iir.~ine Calibration
Type
:;;,;£ :: Stroke
Compression Kutio ..
'Isxiniun Power 0 rpm
':"_ -il "liter Lng ......
l-'uel Acquirement . . .
Jr ive irain
Transmission Type
Final Drive Ratio
Chassis
i.re Size
Curb Weight
Inertia Weight ....
Passenger Capacity
L~ission Control System
Basic Type
Ignition System
Durability Accumulated
or. Svstera
(Information is identical to
first vehicle listed except
as noted.)
Append ix I
VIN' - 1773271310
EE
4 stroke cycle, OHC, I-A
79.5 x 80.0 mm/3.13 x 3.15 in.
1.6L/97 cu. in.
8.0:1
78 HP @ 55OO rpm
Mechanical fuel injection
Regular
Manual 4 speed
3.90:1
Front engine, rear wheel drive
155SR-13, radial, Continental
2250 Ib.
four
Evap., PCV
Breaker points
5000 mi.
V1N - 1773373162
VIN - 1773396532
155SR-13, radial, Michelin
1885 Ib. (w/ full tank)
3900 mi.
*»
155SR^13, radial, Continental^
1955 Ib. (w/ 3/8 tank)
5100 mi.
-------
-35-
Appendix II
Test Emissions
Vehicle Odo .
Chevette (private)
1B08E7Y155084 4900
Chevette (private)
1B08E7Y188038 4800
Chevette (GM)
1B08E7Y109065 7800
Colt (Mitsubishi)
6H41K72401943 3800
Colt (private)
6M21K71102382 8800
Colt (private)
6H45K75115452 4800
Datsun B210+ (private)
HLB210208746 4700
Datsun B210+ (Datsun)
HLB210222360 4700
Datsun B210+ (private)
HLB210202411 4200
Fiat 128 (private)
128A12370659 4100
Fiat 128 (private)
128A12395322 3400
Fiat 128 (Fiat)
128A12314199 3200
Gremlin A-3 (AMC)
A7C465K706587 7300
Gremlin M-4 (private)
A7M464G722317 6600
Gremlin A-3 (private)
A7A464G723693 6900
HC
0.79
0.62
0.89
1.33
1.64
1.58
0.67
0.64
0.56
1.35
0.96
0.60
0.29
1.03
0.34
CO
10.2
9.8
13.8
11.6
16.8
11.5
6.8
6.3
7.5
19.2
16.0
10.7
7.4
8.7
5.5
NOx
1.43
1.14
1.35
1.25
2.58
1.56
1.16
1.49
1.22
1.13
0.95
1.22
1.98
1.30
2.14
Expected 50,000 Mile
Emission Levels
Corrected for Mileage
HC
0.96
0.75
1.09
1.33
1.64
1.58
1.02
0.98
0.86
1.47
1.05
0.60
0.36
1.27
0.42
CO
10.2
9.8
13.8
11.6
16.8
11.5
10.2
9.5
11.3
20.4
16.9
10.7
7.8
9.2
5.8
NOx
1.44
1.14
1.35
1.25
2.58
1.56
1.16
1.49
1.22
1.13
0.95
1.22
1.98
1.30
2.14
-------
-36-
Appendix II (cont.)
Test Emissions
Expected 50,000 Mile
Emission Levels
Corrected for Mileage
Vehicle Odo .
Pinto 2.3L (Ford)
7X11Y187495 5500
Pinto 2.3L (private)
7X11Y185930 6800
Pinto 2.3L (private)
7T11Y115742 7600
Pinto 2.8L (Ford)
7T12Z127330 6000
Pinto 2.8L (private)
7T12Z139162 4200
Sunbird (private)
2M27V72340720 7600
Sunbird (private)
2M27V2332762 3600
Toyota Corolla (Toyota)
KE30224096 4300
Toyota Corolla (private)
KE30167331 7400
Toyota Corolla (private)
KE30178075 5800
VW Rabbit (private)
1773271310 5000
VW Rabbit (VW)
1773373162 3900
VW Rabbit (private)
1773396532 5100
Honda (Canadian)
SGE3511166 7300
Honda (Honda)
SGE3508458 3300
Honda (GM)
SGE3001087
HC
0.72
0.78
0.94
0.73
0.73
1.25
1.53
0.56
0.87
0.74
1.22
1.18
1.36
1.42
1.44
1.15
CO
5.0
3.6
5.4
6.2
7.5
8.6
15.4
8.5
11.3
4.6
6.4
7.1
5.7
5.4
5.4
5.2
NOx
1.55
1.31
1.40
1.28
1.23
1.82
1.68
1.26
1.35
1.87
1.86
1.49
1.60
1.96
1.71
1.72
HC
1.04
1.11
1.33
1.22
1.24
1.42
1.75
0.56
0.87
0.74
1.22
1.18
1.36
1.42
1.44
1.15
CO
6.3
4.5
6.8
7.9
9.6
9.1
16.3
8.5
11.3
4.6
6.4
7.1
5.7
5.4
5.4
5.2
NOx
1.55
1.31
1.40
1.43
1.38
1.89
1.75
1.26
1.35
1.87
2.10
1.69
1.81
1.96
1.71
1.72
-------
Appendix 111
Fuel Economy Results
Certification Vehicle MPG
Vehicle
Chevette, 1.6L
Manual 4, IV,
Cat.
1B08E7Y155084
Chevette 1.6L
Manual 4, IV,
Cat.
1B08E7Y188038
Chevette 1.6L
Manual 4, IV,
Cat.
1B08E7Y109065
Colt, 1.6L
M-4, AIR
Station Wagon
6H45K75115452
Colt, 1.6L
M-4
6H41K72401943
Bronze & White
Colt 1.6L
M-4, AIR
6MZ1K71102382
*Production Mean/EPA results from
cert, vehicle of same calibration.
Manufacturer
FTP HFliT
31.6 43.4
31.6 43.4
31.6 43.4
25.6 38.1
31.5 46.1
31.5 46.1
EPA Mileage Guide EPA
FTP HFET FTP HFET FTP
31.4 43.1 31 43 29.2
27.6
28.5
31.4 43.1 31 43 27.8
27.9
28.5
31.4 43.1 31 43 29.5
29.4
29.6
24.0 36.6 24 37 23.8
24.0
24.0
29.7 47.2 29 45
25.9
25.7
26.4
29.7 47.2 29 45 29.1
28.4
27.9
28.5
HFET
38.6
38.7
37.5
37.2
37.6
38.3
39.9
39.7
39.4
34.8
34.7
35.2
40.1
39.9
39.4
39.8
44.4
42.8
42.8
43.7
Production Vehicle MPG
Std. Dev. [Production Mean/
Mean . as % of Mean Mileage Guide] x 100%
FTP HFET FTP HFET FTP HFET
28.4 38.3 2.!
28.0 37.7
29.5 39.7
23.9 34.9
26.0 39.8
28.5 43.4
i.;
1.7% 92%,
90%*
1.4% 1.5%
0.3% 0.6%
0.5% O.J
1.4% 0.7%
l.i
90%,
89%*
95%,
94%*
100%
100%*
89%,
89%*
88%,
87%*
92%,
92%*
94%
95%*
i
OJ
90%
87%*
96%*
84%*
96%
92%*
-------
Appendix III (cont.)
Certification Vehicle MPG
Production Vehicle MPG
Vehicle
Datsun B210+
1.4L, Manual 5
2V, Cat. , AIR
DHLB210202411
Datsun B210+
1.4L, M5, 2V,
Cat. . MR
DHLB210222360
Datsun 1.4L,
M5 (Datsun)
DHLB21208746
Fiat 128
1.3L, M-4
AIR
128A12314199
Fiat 128, M-4
White
128A12595322
Fiat 128, M-4
Blue
128A12570659
Manufacturer EPA Mileage Guide EPA
FTP HFET FTP HFET FTP HFET FTP
37.4 48.9 37.3 50.5 37 50 31.8
31.7
31.7
37.4 48.9 37.3 50.5 37 50 32.3
31.6
32.9
37.4 48.9 37.3 50.5 37 50 32.3
32.6
32.9
21.1 32.9 23.2 36.3 23 35 22.5
22.5
23.0
21.1 32.9 23.2 36.3 23 35 20.8
21.0
21.1 32.9 23.2 36.3 23 35 22.4
22.7
22.2
HFET
43.9
42.7
44.1
43.6
44.7
43.6
45.3
43.8
44.2
45.5
33.2
33.6
34.3
31.2
31.1
32.6
33.4
33.2
Mean as % of Mean Mileage
FTP HFET FTP HFET FTP
31.6 43.6 1.0% 1.4% 85%
85%*
32.3 44.5 2.0% 1.9% 87%
87%*
32.6 44.5 0.9% 2.0% 88%
87%*
22.7 33.7 1.3% 1.6% 99%
98%*
20.9 31.2 0.7% 0.2% 91%
90%*
22.4 33.1 1.1% 1.3% 97%
97%*
Guide] x 100%
HFET
87%
86%*
89%
88%*
89%
88%*
96%
93%*
89%
86%*
95%
91%*
00
i
*Production Mean/EPA results from
cert, vehicle of same calibration.
-------
Appendix III (cont.)
Certification Vehicle MPG
Manufacturer
Vehicle FTP HFET
Gremlin 19.8 29.5
2.0L, A-3,
Cat. , AIR, EGR
A7A464G723693
Gremlin 21.2 33.3
2.0L, M-4 22.5 33.5
Cat. , AIR, EGR 33.6
A7M464G722317
Gremlin 19.8 29.5
2.0L, A-3
Cat. , AIR, ECR
A7C4G5K706587
Honda 1.5L 42.8 57.1
Manual 5, 3V
Strat. Charge
(supplied by
Honda)
SGE3508458
Honda 1.5L 42.8 57.1
Manual 5, 3V
Strat. Charge
(supplied by
GM)
SGE3001087
Honda 1.5L 42.8 57.1
Manual 5, 3V
Strat. Charge
(Canadian)
SGE3511166
EPA Mileage Guide EPA
FTP HKET FTP HFET FTP
20.6 29.1 21 29 20.8
20.9
20.7
22.2 31.6 21 33 22.8
22.7
22.8
20.6 29.1 21 29 18.9
19.0
18.9
40.8 54.4 40 52 37.0
36.6
36.2
40.8 54.4 40 52 33.3
33.3
32.9
40.8 54.4 40 52 34.0
34.1
35.7
HFET
28.4
28.6
28.5
34.1
34.0
34.7
27.3
27.6
28.4
47.2
47.7
47.9
44.9
45.2
44.3
45.0
45.3
45.9
Production Vehicle MPG
Std. Dev. [Production Mean/
Mean as % of Mean Mileage Guide] x 100%
FTP HFET FTP HFET FTP HFET
20.8 28.5
22.8 34.3
34.6. 45.4
0.5% 0.4%
0.2% 1.1%
18.9 27.8 0.3% 2.(
2.1
1.0%
99%
101%*
108%
103%*
90%
92%*
36.6 47.6 1.1% 0.8% 92%
90%*
33.2 44.8 '0.7% 1.0% 83%
81%*
85%*
98%
98%*
105%
110%*
96%*
92%
88%*
86%
82%*
87%
83%*
*Production Mean/EPA results from
cert, vehicle of same calibration.
-------
Appendix III (cont.)
Certification Vehicle MPG
Manufacturer
EPA
Vehicle
Pinto 2.3L,
Manual 4, 2V,
Calib. //72B-RO
Cat. , AIR
7T11Y115742
Pinto 2.3L,
Manual 4, 2V,
Calib. //72A-R13
Cat. , AIR
7X11Y185930
Pinto 2.3L, M-4,
Calib. 72B-RO
Cat. , AIR
(Ford)
F7X11Y187495
Pinto SW 2.8L,
A-3, calib.
7-4A-R2, Cat. ,
AIR, 30000
7T12Z139162 Ave.
Pinto SW 2.8L,
A-3, Cat. , AIR,
7T12Z127330
FTP
24.1
26.0
24.1
24.9
24.1
26.0
24.1
17.9
17.9
17.8
17.9
18.2
16.4
16.1
16.4
HFET
35.1
36.6
Ave.
37.4
Ave.
35.1
36.6
Ave.
23.1
22.0
23.5
22.9
21.3
22.2
21.3
FTP
23.5
25.2
24.4
27.1
25.1
26.1
23.5
25.2
24.4
HFET
38.4
35.5
37.0
38.6
36.9
37.8
38.4
35.5
37.0
NO EPA DATA
FOR
AVE.
MFR.
17.4
17.0
3000 //
IS OF
DATA
22.7
23.0
Ave.
*Production Mean/EPA results from
cert, vehicle of same calibration.
**Production Mean/Mfr. results from
cert, vehicle of same calibration.
17.2 22.8
Mileage Guide
FTP HFET
26
37
26
37
26
37
18
23
18
23
EPA
FTP
24.3
24.5
24.7
23.8
23.9
23.9
HFET
23.3 34.4
23.6 33.8
23.3 33.4
35.9
35.5
36.8
35.2
33.6
33.9
34.3
19.5 24.3
19.6 23.8
19.2 23.8
18.8 24.2
18.5 . 23.9
18.8 25.1
Production Vehicle MPG
Std. Dev.
Mean as % of Mean
FTP
HFET
23.4 33.9
FTP
0.7%
24.5 35.9
23.9 33.9
19.4 24.0
18.7 24.4
HFET
0.8% 1.9%
0.2% 1.0%
1.1% 1.2%
0.9% 2.6%
[Production Mean/
Mileage Guide] x 100%
FTP HFET
1.5% 90%
96%*
92%
92%*
94%
94%*
92%
98%*
108%
108%**
104%
109%*
97%
95%*
92%
92%*
104%
105%**
106%
107%*
o
i
-------
Appendix III (cont.)
Certification Vehicle MPG
Production Vehicle MPG
Vehicle
Rabbit 1.6L,
Manual 4, Fuel
Injection
1773271310
Rabbit 1.6L
M-4, Fuel
Injection
1773373162
Rabbit 1.6L,
M-4, Fuel
Injection
1773396532
Sunbird, M-4
151 CID
Cat. , EGR
2M27V72332762
Sunbird, M-4
151 CID, Cat. ,
EGR
2M27V72340720
Manufacturer EPA
FTP HFET FTP HFET
21.6 35.1 23.4 36.9
24.4
Ave. 23.9 36.9
21.6 35.1 23.4 36.9
24.4
21.6 35.1 23.4 36.9
24.4
Ave. 23.9 36.9
23.9 35.1 24.9 36.6
26.8 38.9 26.7 38.0
Mileage Guide EPA
FTP HFET FTP
24 37 24.4
24.9
24.8
24 37 23.8
24.2
24.6
24 37 24.6
25.8
25.4
26 37 22.8
22.9
(23.8**)
26 37 25.0
25.2
24.9
HFET
37.4
38.5
37.8
37.9
37.6
37.5
38.1
39.1
38.5
33.7
34.4
34.7
34.7
36.3
36.2
37.3
Mean as % of Mean Mileage
FTP HFET FTP HFET FTP
24.7 37.9 1.1% 1.5% 103%
103%*
24.2 37.7 1.6% 0.6% 101%
101%*
25.3 38.6 2.4% 1.3% 105%
106%*
22.8 34.0 0.3% 1.4% 88%
92%*
23.8 34.7 0.0 92%
96%*
25.0 36.6 0.6% 1.7% 96%
94%*
Guide] x 100%
HFET
102%
103%*
102%
102%*
104%
105%*
92%
93%*
94%
95%*
99%
96%*
*Production Mean/EPA results from
cert, vehicle of same calibration.
**Estimated from Hot LA-4 and previous data.
-------
Appendix HI (conC.)
Certification Vehicle MPG
Production Vehicle MPG
Vehicle
Toyota 1.2L
Manual 5, 2V
Cat (white)
Corolla
(Toyota)
KE30224096
Toyota 1.2L
Manual 4, 2V
Cat. (yellow)
Corolla
KE30169331
Toyota 1.2L,
Manual 4, 2V,
Cat. (silver)
Corolla
KE30178075
Manufacturer
EPA
FTP
36.0
HFET
49.3
FTP HFET
36.3 48.0
Mileage Guide
FTP HFET
36
49
36.6
36.2 48.2 36
49
36.6 47.
36.2 48.2 36
49
EPA
FTP
HFET
32.3 42.0
3i.9 42.6
33.3 44.4
32.1 40.9
31.7 38.2
33.0 41.7
40.8
33.2 41.4
34.2 42.5
34.0 42.9
Std. Dev. [Production Mean/
Mean as % of Mean Mileage Guide] x 100%
FTP HFET FTP HFET FTP HFET
32.5 43.0
2.27. 2.<
90%
90%*
91%
90%*
32.3 40.7
2.0% 3.5%
33.8 42.3
1.6% l.f
90%
89%*
94%
93%*
84%*
86%
88%*
M
I
*Production Mean/EPA results from
cert.vehicle of same calibration.
-------
-43-
Appendix IV
Spread of Vehicle Test Means by Group
FTP
HFET
Mean
for'
each
Vehicle
Chevette (084) 28.4
: (038) 28.0
(065) 29.5
Colt Sed*(943) 26.0
(382) 28.5
Colt Wgn.(452) 23.9
Datsun (411) 31.6
(360) 32.3
(746) 32.6
Fiat (199) 22.7
(322) 20.9
(659) 22.4
Gremlin (693) 20.8
A3 (587) 18.9
Gremlin (317) 22.8
M4
Honda (458) 36.6
(087) 33.2
(166) 34.6
Pinto 2.3(742) 23.4
(495) 23.9
Pinto 2.3(930) 24.5
Pinto 2.8(162) 19.4
Pinto 2.8(330) 18.7
Rabbit (310) 24.7
(162) 24.2
(532) 25.3
Sunbird (762) 23.8
Sunbird (720) 25.0
Toyota M5(096) 32.5
Toyota M4(331) 32.3
(075) 33.8
Average
w/o Colt, Gremlin M4,
and all Pintos
Range of
Mean , means/
for all mean
Vehicles x 100)
28.67 5.23
27.41
23.90
32.20 3.11
22.14 8.13
19.87 9.56
22.77
34.79 9.77
23.63 2.12
24.5
19.4
18.7
24.72 4.45
23.8
25.0
32.50
33.03 4.54
5.86%
Mean
for
each
Vehicle
38.3
37.7
39.7
39.8
43.4
34.9
43.6
44.5
44.5
33.7
31.2
33.1
28.5
27.8,
34.3
47.6
44.8
45.4
33.9
33.9
35.9
24.0
24.4
37.9
37.7
38.6
34.7
36.6
43.0
40.7
42.3
Mean
for all
Vehicles
38.58
41.61
34.90
44.14
32.83
28.13
34.3
45.93
33.9
35.85
23.97
24.4
38.04
34.7
36.6
43.00
41.26
Range of
means/
mean
x 100)
5.18
2.04
7.61
2.49
6.10
0
2.37
3.88
3.71%
*Two different axle ratios.
-------
Appendix V
Vehicle-to-Vehicle Individual Test Variability of Fuel Economy Within Each Model
i
1 of
Vehicles
Model In
Chevette
Colt Sedan
Colt Sta. Wgn.
Datsun
Fiat
Gremlin A3
Gremlin M4
Honda
Pinto 2.3*
Pinto 2.3*
Pinto 2.8*
Pinto 2.8*
Rabbit
Sunbird
Sunbird**
Toyota M5
Toyota M4
Group
3
2
1
3
3
2
1
3
2
1
1
1
3
1
1
1
2
FTP Range
27.6-29.6
25.7-29.1
23.8-24.0
31.7-32.9
21.0-23.0
18.9-20.9
22.7-22.8
32.9-37.0
23.3-23.9
24.3-24.7
19.2-19.5
18.5-18.8
23.8-25.8
23.8
24.9-25.2
31.9-33.3
31.7-34.2
Mean of
Individual
Tests
28.67
27.41
23.9
32.20
22.14
19.87
22.77
34.79
23.63
24.5
19.43
18.7
24.72
23.8
25.0
32.50
33.03
(Range/Mean)
x 100%
6.98%
12.40%
0.84%
3.73%
9.03%
10.07%
0.44%
11.78%
2.54%
1.63%
1.54%
1.60%
8.09%
1.20%
4.31%
7.57%
HFET Range
37.2-39.9
39.4-44.4
34.7-35.2
42.7-45.5
31.1-34.3
27.3-28.6
34.0-34.7
44.3-47.9
33.4-34.4
35.2-36.8
23.8-24.3
23.9-25.1
37.4-39.1
34.7 .
36.2-37.3
42.0-44.4
38.2-42.9
Mean of
Individual
Tests
38.58
41.61
34.9
44.14
32.83
28.13
34.27
45.93
33.9
35.85
23.97
24.4
38.04
34.7
36.6
43.00
41.26
(Range/Mean)
x 100%
7.01%
12.02%
1.43%
6.34%
9.75%
4.62%
2.04%
7.84%
2.95%
4.46% i
2.09% *
4.92%
4.47%
0%
3.01%
5.58%
11.39%
* Different calibrations
**Different axle ratios
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-45-
Appendix VI
Production Vehicle Fuel Economy Percent
Shortfall from Certification Vehicle Values
in Order of Decreasing Shortfall
( ) - indicates production value greater than certification value
Honda
Datsun
Toyota M5
Colt Sedan
Toyota M4
Chevette
Sunbird**
Pinto 2.3L*
Fiat
Sunbird**
Gremlin A3
Pinto 2.3L*
Colt S.W.
Gremlin M4
Rabbit
Pinto 2.8L*
Pinto 2.8L*
Honda
Toyota M4
Datsun
Colt (sedan)
Chevette
Toyota M5
Fiat
Pinto 2.3L*
Sunbird**
Pinto 2.3L*
Colt S.W.
Sunbird**
Gremlin A3
Rabbit
Pinto 2.8L*
Pinto 2.8L*
Gremlin M4
% Shortfall FTP
Model Mean
14.7
13.7
10.5
10.1
8.8
8.7
6.2
6.1
4.6
4.4
3.6
3.1
0.4
(2.7)
(3.4)
(8.4)
(8.7)
% Shortfall HFET
Model Mean
15.6
14.4
12.6
11.8
10.6
10.4
9.6
8.4
5.2
5.0
4.6
3.7
3.3
(3.1)
(4.8)
(7.0)
(8.5)
Shortfall
Vehicle Mean
10.3/18.6/15.2
15.3/13.4/12.6
10.5
12.5/4.0
10.8/6.6
9.6/10.8/6.0
6.2
6.1
2.2/9.9/3,4
4.4
1.0/8.2
4.1/2.0
0.4
(2.7)
(3. 4)/l. 3/(5.9)
(8.4)
(8.7)
Vehicle Mean
12.5/17.6/16.5
15.6/12.2
13.7/11.5/11.9
15.7/8.0
11.1/12.5/7.9
10.4
7.2/14.0/8.8
8.4/8.4
5.2
5.0
4.6
3.7
2.1/4.5
Rank
1
2
3
4
5
6
7
8
9
10
11
12
13
1
2
3
4
5
6
7
8
9
10
11
12
13
Overage
Rank
4
3
2
1
(2.7)7(2.2)7(4.6)
(4.8)
(7.0)
(8.5)
4
3
2
1
*Separated by individual calibration,
**Separated by axle ratios.
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