EPA-AA-TEB-81-6
Testing of Five Diesel-Powered Passenger Cars
at High and Low Altitude
Thomas A. Tupaj
October 1980
Test and Evaluation Branch
Emission Control Technology Division
Motor Vehicle Emission Laboratory
U.S. Environmental Protection Agency
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Abstract
A group of five in-use diesel-powered passenger cars was tested for emissions
and fuel economy at both high altitude and low altitude locations. The test
sequence consisted of the current Federal Test Procedure (FTP) and the Highway
Fuel Economy Test (HFET). Particulate emissions were also measured over both
cycles at both locations. On the average, a substantial increase was noted at
high altitude for hydrocarbons, carbon monoxide and particulates as compared
to the low altitude measurements. As measured over the FTP, the average
increases for these three pollutants were 130%, 75% and 45% respectively.
Results of the HFET were in the same direction but were of a slightly smaller
magnitude. The emission levels of oxides of nitrogen were approximately the
same at each location. The average fuel economy values at high altitude were
approximately 14% lower than those at low altitude.
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Background
Although the diesel engine has long been used as a powerplant for commercial
vehicles, its application to passenger cars had been limited due to factors
such as weight, noise and cost. The changing economic and political situation
has recently made this concept more feasible. Although several manufacturers,
such as Mercedes-Benz and Peugeot, have been in the market for some time, the
diesel engines recently introduced by Oldsmobile and Volkswagen have quickly
gained a small but growing share of new-car sales. Because the potential
exists for widespread use of diesel engines in all parts of the country, there
is a need to obtain information concerning the emission levels of these ve-
hicles when operated at high altitude locations.
Purpose
The purpose of this project was to assess the effect of altitude on the emis-
sion characteristics of diesel-powered, in-use passenger cars. This infor-
mation will be used to project the emission characteristics of the high alti-
tude fleet as well as for evaluation of new or expanded standards.
Program Design
This program was developed to test a sample of vehicles at low altitude and
subsequently at high altitude. The low altitude testing was performed at
EPA's Motor Vehicle Emission Laboratory (MVEL) in Ann Arbor. Testing at high
altitude was performed by Automotive Testing Laboratories (ATL) in Aurora, CO.
The vehicles were tested at each location without mileage accumulation or
adjustments between the test sequences. The same fuel was also used at both
locations. The test sequences consisted of the current Federal Test Procedure
(FTP) and the Highway Fuel Economy Test (HFET). Particulate emissions were
also measured during each of these driving cycles.
The vehicles chosen for this program represented the more common diesel engine
passenger cars available to the consumer. All were in daily use by private
owners at the time they were recruited into the program. The characteristics
of the test vehicles are as follows:
#241 1980 Volkswagen Rabbit: 4 cylinder; 90 CID; Manual 5 speed;
VIN-17A0815408; Engine Family-D; Odometer-5579
#242 1979 Oldsmobile Cutlass Supreme: 8 cylinder; 260 CID; Automatic trans-
mission; VIN-3R47P9M535761; Engine Family-930H9; Odometer-8930
#243 1979 Oldsmobile Cutlass Supreme: 8 cylinder; 260 CID; Automatic trans-
mission; VIN-3R47P9M540008; Engine Family-930H9; Odometer-13301
#244 1974 Peugeot 504: 4 cylinder; 129 CID; Manual 4 speed; VIN
504D90-1759613; Odometer-73252
#245 1977 Mercedes Benz 240D: 4 cylinder; 147 CID; Automatic transmission;
VIN-123.123-12015320; Engine Family-77/2/L-4D/2.4; Odometer-52206
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Conduct of the Program
The responsibility for the project was assigned to Automotive Testing Labor-
atories in April, 1980, under EPA contract No. 68-03-2891. They arranged for
the procurement of the vehicles through a leasing firm in St. Louis. The
vehicles were shipped to Ann Arbor in May. Upon arrival at the MVEL, each
vehicle was inspected to insure it was in proper operating order. Two or
three test sequences were performed on each vehicle to obtain the low-altitude
baseline. The vehicles were then shipped to the Denver area for testing by
ATL at their laboratory in Aurora. Identical test procedures using equivalent
test equipment were performed there in July. No maintenance or adjustments
were performed on any vehicle before testing at the high-altitude location.
Test Results
The average FTP emission levels for each vehicle at each location are shown in
Table 1. Results from the HFET are displayed in Table 2. A listing of all
test results on each vehicle is attached as Appendices A and B while ATL's
report on the program (Reference 1) contains details on the test procedures.
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Table 1
Average FTP Emission Levels of Diesel-Powered Passenger Cars
Vehicle
#241 80 Volkswagen
90 CID
Odometer-5579
#242 79 Olds
260 CID
Odometer-8930
#243 79 Olds
260 CID
Odometer-13301
#244 74 Peugeot
129 CID
Odometer-73252
#245 77 Mercedes
147 CID
Odometer-52206
Average (all vehicles)
Increase
Average (without #244)
Increase
Test
Site
High
Low
High
Low
High
Low
High
Low
High
Low
High
Low
High
Low
HC
(g/mi)
.57
.22
1.39
.68
.97
.39
6.74
3.86
.65
.25
2.06
1.08
91%
.89
.38
134%
CO
(g/mi)
1.88
.78
2.21
1.50
2.57
1.49
8.88
3.83
1.04
.67
3.32
1.65
101%
1.93
1.11
74%
NOx
(g/mi)
1.09
1.05
1;29
1.43
1.56
1.67
.98
.93
1.51
1.29
1.28
1.27
1%
1.36
1.36
0%
F.E.
(mi/gal)
35.3
39.5
20.5
22.9
20.6
24.2
21.0
25.2
25.8
31.8
23.6
27.6
-14%
24.3
28.2
-14%
Part.
(g/mi)
.40
.26
.98
.78
1.82
1.13
2.43
2.43
.47
.36
1.22
.69
78%
.92
.63
46%
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Table 2
Average HFET Emission Levels of Diesel-Powered Passenger Cars
Vehicle
#241 80 Volkswagen
90 CID
#242 79 Olds
260 CID
#243 79 Olds
260 CID
#244 74 Peugeot
129 CID
#245 77 Mercedes
147 CID
Average (all vehicles)
Increase
Average (without #244)
Increase
Test
Site
High
Low
High
Low
High
Low
High
Low
High
Low
High
Low
High
Low
HC
(g/mi)
.35
.13
.47
.29
.36
.22
1.87
1.44
.26
.13
.66
.44
50%
.36
.19
89%
CO
(g/mi)
1.42
.47
1.04
.79
1.27
.82
3.55
1.70
.63
.57
1.58
.87
82%
1.09
.66
65%
NOx
(g/mi)
.81
.73
1.20
1.23
1.45
1.59
1.08
.88
1.68
1.42
1.24
1.17
6%
1.29
1.24
4%
F.E.
(mi /gal)
42.7
51.8
28.5
32.0
29.1
33.6
25.9
33.1
28.3
33.5
30.0
35.6
-16%
31.2
36.3
-14%
Part.
(g/mi)
.34
.19
.72
.48
1.12
.74
.69
.38
.23
.36
.62
.43
44%
.60
.44
36%
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Discussion of Test Results
As seen in Tables 1 and 2, the emission levels of unburned hydrocarbons (HC),
carbon monoxide (CO) and particulates for each vehicle were substantially
greater at high altitude. Despite this increase, the average levels for three
of the vehicles are still below the standards under which they were certified.
In the case of the 1980 Volkswagen, however, the effect of altitude on HC
emissions put it over its .41 g/mi standard. The 1974 Peugeot failed HC at
both altitudes. Although the emission levels of oxides of nitrogen (NOx)
increased very slightly, the scatter in the data implies that the overall
change in emissions of this pollutant may not be significant. Since vehicle
No. 244, the 1974 Peugeot, was so different from the rest, in age, appearance
and performance, the possibility exists that it had been improperly
maintained. It could be concluded that this vehicle may not be representative
of the current fleet. Therefore, the averages have also been calculated
without its results. These values are also shown on Tables 1 and 2. For the
remaining vehicles, the fuel economy penalty for operation at high altitude
was quite apparent and consistent at about 14%.
Shown in Table 3 are the emission rates and fuel economy of a representative
fleet of late model, gasoline-powered passenger cars tested at high altitude
(Reference 2). These may be compared to the results of the four late model,
diesel-powered cars tested in this program.
Table 3
Estimated Emission Levels of Late Model Passenger Cars at High Altitude (g/mi)
FTP
H£ C0_ NOx Part.
These four late model .9 1.9 1.4 .9 ' .6
diesel-powered cars
Typical Late-model, gasoline-
powered cars (average odometer 2.6 45.0 1.2 * *
20,000 miles)
*Data on particulate emissions from gasoline-powered vehicles is currently
being obtained in another test program.
Table 4 is a listing of these percentage increases compared to average emis-
sion and fuel economy changes expected of low altitude vehicles which are
tested at high altitude. For the gasoline-powered vehicles the projection of
emission changes was derived from information contained in Reference 2. The
values for fuel economy penalty were determined by a comparison of results
between identical vehicles tested at high and low altitude sites in the FY79
Passenger Car Emission Factor Testing Program.
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Table 4
Changes In from Low Altitude Baseline Emissions (g/mi) and
Fuel Economy (mi/gal) at High Altitude
FTP HFET
HC C£ NOx MPG Part. MPG Part.
Four late-model diesel- +134% +74% 0% -14% +46% -14% +36%
powered cars
Typical late-model gaso-
line powered cars + 35% +80% -35% - 7% * - 7% *
*Data on particulate emissions from gasoline-powered vehicles is currently
being obtained in another test program.
Conclusions
Based on the results of this program there are several conclusions which may
be drawn:
1. Diesel-powered passenger cars tuned to operate at low altitude and
subsequently operated at high altitude produce substantially greater
amounts of HC, CO and particulates.
2. Despite their increased levels, HC and CO emissions from diesel-
powered cars are still much lower than those from similar
gasoline-powered vehicles operated at high altitude. On the other
hand, levels of particulates may become of even greater concern.
3. There is a penalty in fuel economy apparent when a vehicle designed
for low altitude is operated at high altitude. Diesel vehicles
appear to suffer more than gasoline-powered models with respect to
fuel economy.
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References
1. Report from Automotive Testing Laboratories entitled "Tests on Five
Diesel Passenger Cars at High Altitude", EPA Contract No.
68-03-2891, Task #1, September 1980
2. Jay S. Wallace, "Draft Compilation of Air Pollutant Emission Factors
for On-Highway Mobile Sources, (AP-42)".
3. Report from Automotive Testing Laboratories entitled "Effect of
Altitude on Maladjusted Vehicles", EPA Contract No. 68-03-2891, Task
No. 2, Due November, 1980.
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