RENTAL VEHICLE
SURVEILLANCE PROGRAM
March 1968 to January 1970
•/ /
-------
RENTAL VEHICLE
SURVEILLANCE PROGRAM
March 1968 to January 1970
Daniel B. Pinkert,
James M. Marzen, and
Charles J. Domke
Bureau of Mobile Source Pollution Control
ENVIRONMENTAL PROTECTION AGENCY
Office of Air Programs
Research Triangle Park, North Carolina
November 1971
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C., 20402 - Price 25 cents
-------
The AP series of reports is issued by the Environmental Protection Agency to
report the results of scientific and engineering studies, and information of general
interest in the field of air pollution. Information presented in this series includes
coverage of intramural activities involving air pollution research and control tech-
nology and of cooperative programs and studies conducted in conjunction with
state and local agencies, research institutes, and industrial organizations.
Copies of AP reports are available free of charge - as supplies permit - from the
Office of Technical Information and Publications, Office of Air Programs, Envi-
ronmental Protection Agency, Research Triangle Park, North Carolina 27711-
Office of Air Programs Publication No. AP-97
11
-------
CONTENTS
Page
LIST OF FIGURES iv
LIST OF TABLES iv
ABSTRACT v
INTRODUCTION 1
TEST VEHICLES AND PROCEDURES 5
Test Vehicles 5
Exhaust Emission Study Procedures 8
RESULTS 9
SUMMARY AND CONCLUSIONS 19
in
-------
LIST OF FIGURES
Figure Page
1 Unbumed Hydrocarbon Emissions versus Cumulative Percen-
tage of Domestic Cars Represented by Test Sample. (Test
Sample Represents 65 Percent of Combined 1968 Plus 1969
Production, with Percentages Weighted According to Produc-
tion.) 17
2 Carbon Monoxide Emissions versus Cumulative Percentage
of Domestic Cars Represented by Test Sample. (Test Sample
Represents 65 Percent of Combined 1968 Plus 1969 Produc-
tion, with Percentages Weighted According to Production.) ... 17
LIST OF TABLES
Table Page
1 Test Vehicles and Their Estimated Distribution in Manufac-
turer and National Vehicle Populations 6
2 Mean Emission Concentrations for All Displacement Groups
with 15 or More Tests 10
3 Mean Emission Concentrations for All Displacement Groups
with 15 or More Tests (Tests on Vehicles with Less
than 3,500 Miles Eliminated) 11
4 Percentage of Cars with Emissions Exceeding Standards (For
All Displacement Groups with 15 or More Tests) 12
5 Mean Emission Concentrations for All Displacement Groups
with Less than 15 Tests _ 14
6 Mean Emission Concentrations for All Displacement Groups
with Less than 15 Tests (Tests on Vehicles with Less than
3,500 Miles Eliminated) 15
7 Percentage of Cars with Emissions Exceeding Standards (For
All Displacement Groups with Less than 15 Tests) 16
8 Data Summary 18
IV
-------
ABSTRACT
Exhaust-emission tests were performed on rental vehicles representing 26
vehicle types to ascertain the effectiveness of the Federal exhaust emission
standards. Most of the rental vehicles tested had odometer readings of less
than 15,000 miles, and had received no engine maintenance other than minor
carburetor adjustments. Approximately half the cars with odometer readings
in excess of 15,000 miles had received one engine tune-up during their fleet
operation.
All vehicles were tested by the standard Federal seven-mode, seven-cycle
cold-start test procedure, and by the New Jersey ACID cycle test and the
Clayton Key Mode test.
Although exhaust emissions varied considerably among automobiles of
different manufacturers, among engines of different types, and among dif-
ferent engines of the same type, most types of engines tested produced emis-
sions at levels below those permitted by Federal standards. More than 80
percent, however, of the Chevrolet 307-CID engines operated for at least
3,500 miles exceeded the Federally established levels. Ford 289- and 302-CID
engines also had high emission levels.
Approximately 75 percent of the test vehicles, of types representing
about two-thirds of the 1968 and 1969 domestic automobile population,
emitted hydrocarbons at levels lower than those permitted by the Federal
certification standards, and about 60 percent emitted carbon monoxide at
levels lower than those permitted. Projections indicate, however, that a smaller
percentage of the vehicles represented in this test program will meet certifi-
cation standards when they have been operated 50,000 miles.
-------
RENTAL VEHICLE SURVEILLANCE PROGRAM,
MARCH 1968 TO JANUARY 1970
INTRODUCTION
The nuisance problem and health hazards of automotive air pollution have
received increasing recognition and study over the past decade. The United
States Congress passed the Clean Air Act of 1963 to improve, strengthen, and
accelerate programs for the prevention and abatement of air pollution. This
act, as amended in 1965, authorized the United States Department of Health,
Education, and Welfare—under which the national air pollution control pro-
gram was administered until late 1970—to set national standards for the
control of air pollution from new motor vehicles. Standards were issued in
early 1966 that established maximum permissible concentrations for hydro-
carbon (HC) and carbon monoxide (CO) emissions from automobiles and
light-duty trucks sold in the United States, beginning with the 1968 model
year. The Federally established maximum allowable concentrations of HC and
CO emissions from 1968 and 1969 vehicles, which vary according to the
cubic-inch displacement (CID) of the engine,* are listed below:
CID HC, ppm CO, %
50 to 100 410 2.3
100 to 140 350 2.0
=»140 275 1.5
Procedures for testing and certifying prototype vehicles for compliance
with Federal exhaust emission standards were drafted and published in the
Federal Register 31(61), March 30, 1966. These procedures required each
manufacturer to build and test a specified number of prototype vehicles that
would meet Federal emission standards before Certificates of Conformity were
issued to the manufacturer. The procedures did not require that each vehicle
*For a 4,000-pound car with an automatic transmission, 275 parts per million
(ppm) HC is equivalent to 3.5 grams HC per mile, and 1.5 percent CO is
equivalent to 36 grams CO per mile. The 1970 standards are 2.2 grams HC
per mile and 23 grams CO per mile. The vehicles involved in this test pro-
gram were not required to meet the 1970 standards, however, inasmuch as
they were 1968 and 1969 models.
-------
produced meet the applicable standards. They did require that the average
emission values from a sample of two or four emission-data vehicles of each
displacement, depending on projected sales volume, be less than the values
stated in the standards, when the values had been modified by a deterioration
factor obtained from a fleet of four to ten durability-data vehicles, represen-
tative of at least 70 percent of the manufacturer's engine displacement and
transmission options.
The Federal procedures and standards applicable to 1968- and 1969-
model vehicles were similar to those of California, which became effective
with 1966 models built for sale in that state. After the 1966 models were
introduced for sale, the California authorities, with Federal financial assis-
tance, initiated a program by which to survey the effectiveness of the certified
emission-control systems on production, as opposed to prototype, vehicles
operated routinely by the ultimate consumer. Periodic reports resulting from
this continuing program indicated that emissions from the 1966 models de-
viated substantially from the standards, especially with increasing mileage. The
performance for 1967 and subsequent model-year vehicles was generally
better. The results reported by California were obtained from "hot start" tests
corrected to "cold start" values by means of average adjustment factors that
had been determined experimentally for carbon monoxide and hydrocarbons.
The purpose of the Rental Vehicle Survey was to ascertain the effective-
ness of the Federal air pollution regulations by measuring emissions from
vehicles driven by the motoring public. Between March 1, 1968, and January
13, 1970, 705 exhaust-emission tests were performed by the Environmental
Protection Agency (EPA) at the Los Angeles, California, and Ypsilanti, Mich-
igan, test facilities of EPA's Bureau of Mobile Source Pollution Control on
rental vehicles representing 26 different vehicle types. Besides being used to
give an indication of the exhaust-emission levels of vehicles in general use,
these tests were designed to provide the background information necessary for
efficiently planning future surveillance programs for privately owned vehicles.
Vehicles for this program were obtained from the Hertz and Airways
rental companies in Los Angeles and from the Hertz and Avis companies in
Detroit. Although such rental vehicles may differ from privately owned ve-
hicles with respect to the care with which they are driven, the maintenance
they receive, and the type and rate of mileage accumulated, no data are
available that define such differences. Lacking data to the contrary, there is
no reason to believe that the two groups have different exhaust-emission char-
acteristics.
The original plan for this program was to start with a basic fleet of 138
vehicles, 1968-model year, that would be retested at 3,000- to 4,000-mile
intervals. These vehicles were chosen to represent many of the high-production
vehicles sold in the United States. Within a short period of time, however, it
became apparent that the rental companies could not deliver the vehicles for
repetitive testing at the required intervals. In addition, policy changes by the
RENTAL VEHICLE SURVEILLANCE PROGRAM
-------
rental companies resulted in the retention of most rental vehicles for less than
1 year of operation, thereby eliminating any possibility of obtaining large
samples of vehicles with more than 20,000 accumulated miles. Hence the
surveillance program had to be reorganized to reflect non-repetitive testing of
vehicles and the inclusion of low-mileage, 1969-model vehicles in the test
fleet.
Introduction
-------
TEST VEHICLES AND PROCEDURES
TEST VEHICLES
The vehicles tested in this program are listed in Table 1. All vehicles,
except Volkswagens, were equipped with automatic transmissions, and all ve-
hicles except Cadillacs had engine-modification emission-control systems. The
Cadillacs used an air-injection emission-control system. Most engines of a given
make and displacement constituted a homogeneous population inasmuch as
only one version was tested. Thus, even though Ford Motor Company's
390-CID engine was produced in both two-barrel- and four-barrel-carburetor
versions, data were obtained with the two-barrel model only. The 1968 Chev-
rolet 327-CID engines differed from the same 1969 engines in carburetion and
in compression ratio. The difference between 1968 and 1969 versions of all
other engines was considered small enough to allow data from the two model
years to be combined. Because the 350-CID engines used by General Motors'
Buick, Chevrolet, Oldsmobile, and Pontiac Divisions differed in design, a
separate analysis was needed for each division's engines.
All test results for a given engine type were combined without regard for
body style. Thus, all test results on Ford Motor Company's 302-CID engines
were combined even though the test fleet for this engine included a mix of
Mercury Cougars, Ford Galaxies, and Ford Mustangs. Similarly, data on
Chrysler Corporation's 318-CID engine were obtained by testing both Ply-
mouths and Dodges.
The number of 1968- and 1969-model-year, and 1968- plus 1969-model-
year cars tested in each displacement group is given in Table 1 along with
estimates of the proportionate use of a particular engine in the total popula-
tion of domestic cars. These population estimates are described below:
Column heading Meaning
% of manufacturer's The percentage of the manufacturer's out-
output put that uses the particular engine type.
% of total vehicle The percentage of the total car population
population under consideration that uses the particular
engine type.
All three rental-car companies received their vehicles from local new-car
dealers and not directly from the manufacturers. They did not usually rely on
one dealer for all vehicles of a certain model, but received vehicles from many
-------
Table 1. TEST VEHICLES AND THEIR ESTIMATED DISTRIBUTION IN MANUFACTURER
AND NATIONAL VEHICLE POPULATIONS
Manufacturer
Domestic
American Motors
Corporation
Total
Chrysler
Corporation
Total
Ford Motor
Company
Total
General Motors
Corporation
Chevrolet
CID
290
343
225
318
383
440
200
289
302
351
390
429
460
462
230
307
Carbu-
retor
barrels
2
2
1
2
2
4
1
2
2
2
2
4
4
4
1
2
1968
Number
tested3
19
8
27
0
40
2
0
42
0
45
78
0
56
8
1
5
193
0
24
% of
mfr. output
28.75
7.19
35.94
15.74
33.89
23.32
9.58
57.21
7.40
13.87
32.34
0.00
19.96
3.40
1.23
0.89
71.69
2.39
17.99
% of total
U.S. vehicles
0.92
0.23
2.99
6.44
4.43
1.82
1.74
3.26
7.60
0.00
4.69
0.80
0.29
0.21
1.30
9.77
1969
Number
tested3
13
4
17
21
9
5
3
38
11
0
32
13
62
0
4
0
122
5
24
% of
mfr. output
29.70
12.73
42.43
10.40
34.09
21.20
9.96
75.65
4.16
0.00
32.36
13.54
24.54
4.71
2.88
0.00
77.48
2.65
6.10
% of total
U. S. vehicles
0.98
0.42
1.88
6.16
3.83
1.80
1.07
0.00
8.32
3.48
6.31
1.21
0.74
0.00
1.40
3.23
1968 plus 1969
Number
tested3
32
12
44
21
49
7
3
80
11
45
110
13
118
8
5
5
315
5
48
% of
mfr. output
29.23
9.85
39.08
13.17
34.00
22.29
9.77
79.23
5.69
6.62
32.34
7.07
22.35
4.06
2.11
0.41
80.65
2.52
12.12
% of tota I
U. S. vehicles
0.95
0.32
2.44
6.30
4.13
1.81
1.40
1.63
7.96
1.74
5.50
1.00
0.52
0.10
1.35
6.50
m
O
GO
I
O
m
-a
x
O
O
•30
-------
Table 1 (continued). TEST VEHICLES AND THEIR ESTIMATED DISTRIBUTION IN MANUFACTURER
AND NATIONAL VEHICLE POPULATIONS
CD
CD
(A
fi)
Q_
O
CD
Q.
^
CD
V)
Manufacturer
Domestic
General Motors
Corporation
Chevrolet
(continued)
Pontiac
Oldsmobile
Cadillac
Total
Total domestic
Foreign
Volkswagen
Grand Total
CID
327
327
350
350
400
428
350
455
472
92
Carbu-
retor
barrels
4
2
4
2
4
4
2
4
4
1
1968
Number
tested3
48
0
0
14
6
0
0
8
8
108
370
0
370
%of
mfr. output
6.17
0.00
0.00
5.75
6.17
0.00
5.06
2.87
4.97
43.92
-
% of total
U.S. vehicles
3.35
0.00
0.00
3.12
3.35
0.00
2.75
1.56
2.70
63.32
-
1969
Number
tested8
0
53
5
11
17
4
4
0
0
123
300
35
335
%of
mfr. output
0.00
13.83
6.90
5.16
4.04
2.80
5.57
7.14
5.06
47.05
-
% of total
U.S. vehicles
0.00
7.32
3.65
2.73
2.14
1.48
2.95
3.78
2.68
67.56
-
1968 plus 1969
Number
tested8
48
53
5
25
23
4
4
8
8
231
670
35
705
%of
mfr. output
3.13
6.83
3.39
5.45
5.11
1.38
5.32
4.98
5.02
55.25
-
% of tola I
U.S. vehicles
1.68
3.66
1.82
2.92
2.74
0.74
2.85
2.67
2.69
65.44
-
3lf "Number tested" was zero, production percentage was excluded from totals.
-------
different dealers. All vehicles reportedly received normal dealer make-ready
servicing before delivery to the rental-car companies.
Although there were significant differences in the maintenance practices
of the three rental-car companies used as vehicle sources for this program,
some generalizations can be made about maintenance of the test vehicles. The
great majority of vehicles tested in this program with odometer readings of
15,000 miles or less had no engine maintenance other than minor carburetor
adjustments performed on them between new-car dealer preparation and the
time of test. Approximately half of the cars with greater than 15,000 ac-
cumulated miles had their engines tuned once during their fleet operation
prior to testing.
EXHAUST EMISSION STUDY PROCEDURES
All vehicles were tested by the standard Federal seven-mode, seven-cycle
cold-start test procedure as described in the Federal Register 31^(61), II, Para-
graphs 85.70-85.83. Following each cold-start test, a New Jersey ACID Cycle
test and a Clayton Key Mode test were performed to determine the feasibility
of using short exhaust-emission tests as predictors of the Federal seven-mode,
cold-start emission test. Data from these short tests are being used in a study
of inspection procedures and are not presented in this report.
RENTAL VEHICLE SURVEILLANCE PROGRAM
-------
RESULTS
Table 2 presents the mean exhaust-emission levels for those 12 displace-
ment groups for which data from 15 or more vehicles were obtained. The
table includes the average odometer reading and the averages of the three
lowest and of the three highest odometer readings of the vehicles tested; the
last two values give the range of mileage for the vehicles tested. The average
exhaust emissions are given as arithmetic mean values.
Analysis of the exhaust-emission data for the individual engine-displace-
ment groups revealed that the hydrocarbon and carbon monoxide concen-
trations were lognormally rather than normally distributed; that is, the
logarithms of the values closely approximated a normal distribution. The
geometric mean is the value corresponding to the average of the logarithms;
the HC and CO geometric mean concentrations are listed in Table 2. (For a
group of values whose logarithms are normally distributed, half of the values
will be above and half below the geometric mean. The probability is 95
percent that the true value of the geometric mean is between the lower
confidence limit (LCL) and the upper confidence limit (UCL).)
Table 3 presents the mean exhaust-emission levels for those vehicles that
had accumulated at least 3,500 miles. Although tests were conducted on a
number of vehicles with lower mileage to develop some background-emissions
information on engines not fully broken in, data from these tests were
eliminated from this analysis for two reasons. First, emissions produced by
vehicles with low mileage—before piston rings have seated and equilibrium
combustion chamber deposits have accumulated—were suspected to be erratic
and to change rapidly as mileage was accumulated; thus they could not be
used to develop real-life data that could be compared with the 4,000- to
50,000-mile values, modified by deterioration factors, that were determined
from certification prototypes. Second, some displacement groups contained
vehicles with low mileage and others did not, and the elimination of the
low-mileage tests tended to equalize the average odometer readings for each
group, making comparisons of emission data among groups more meaningful.
In general, the average HC emissions were somewhat higher for the groups
of cars with more than 3,500 miles than for the corresponding groups con-
taining all cars tested, regardless of odometer readings. The differences in
average CO values were slight.
Table 4 presents the percentage of cars in each displacement group, from
which 15 or more cars were tested, that produced HC and/or CO emissions in
excess of the limits prescribed by Federal standards. Results obtained after
eliminating data from cars with fewer than 3,500 miles are also presented.
-------
Table 2. MEAN EMISSION CONCENTRATIONS FOR ALL DISPLACEMENT GROUPS WITH 15 OR MORE TESTS
Manufacturer
American Motors
Corporation
Chrysler
Corporation
Ford Motor
Company
General Motors
Corporation
Chevrolet
1968
1969
Pontiac
Volkswagen
CID
290
225
318
289
302
390
307
327
327
350
400
92
Mumber
tested
32
21
49
45
110
118
48
48
53
25
23
35
Odometer readings
Average
5,133
13,568
4,991
10,994
8,953
3,044
9,548
16,960
5,611
9,631
6,492
9,914
Average of
minimum 3
263
4,272
34
4,050
940
34
1,088
6,525
44
486
1,550
53
Average of
maximum 3
10,709
24,086
14,265
21,397
21,821
24,199
20,311
25,991
22,391
17,187
12,042
18,364
Hydrocarbon emissions, ppm
Arithmetic
mean
213
215
230
320
305
228
325
289
231
219
176
372
Geometric
mean
211
212
226
304
294
213
299
282
226
215
173
359
LCLa
199
195
214
279
279
201
268
264
213
198
159
328
UCLb
223
229
239
332
308
226
334
300
239
233
188
393
Carbon monoxide emissions, %
Arithmetic
mean
1.13
1.70
1.09
1.39
1.19
1.11
1.52
1.76
1.56
1.55
1.46
2.14
Geometric
mean
1.06
1.56
1.01
1.22
1.04
0.89
1.40
1.66
1.46
1.42
1.40
1.97
LCLa
0.91
1.29
0.91
1.06
0.95
0.80
1.23
1.49
1.32
1.17
1.23
1.74
UCLb
1.23
1.89
1.13
1.41
1.14
0.99
1.60
1.84
1.62
1.72
1.59
2.23
m
I
O
C/5
30
>
O
-o
30
O
O
30
aLCL = Lower confidence limit of 95-percent confidence
UCL : Upper confidence limit of 95-percent confidence
interval on geometric mean.
interval on geometric mean.
-------
30
CD
(A
C
Table 3. MEAN EMISSION CONCENTRATIONS FOR ALL DISPLACEMENT GROUPS WITH 15 OR MORE TESTS
(Tests on vehicles with less than 3,500 miles eliminated)
Manufacturer
American Motors
Corporation
Chrysler
Corporation
Ford Motor
Company
General Motors
Corporation
Chevrolet
1968
1969
Pontiac
Volkswagen
CID
290
225
318-
289
302
390
307
327
327
350
400
92
Number
tested
24
20
28
44
95
72
36
48
32
21
21
30
Odometer readings
Average
6,157
14,178
8,125
11,191
10,038
12,461
12,040
16,960
8,354
11,236
7,061
1 1 ,537
Average of
minimumS
3,690
6,739
3,661
4,902
3,827
4,384
4,773
6,525
3,817
5,536
3,703
5,531
Average of
maximum 3
10,709
24,086
14,265
21 ,397
21 ,821
24,199
20,311
25,991
22,391
17,187
12,042
18,364
Hydrocarbon emissions, ppm
Arithmetic
mean
218
215
240
323
314
252
355
289
251
215
177
391
Geometric
mean
216
212
234
308
303
232
328
282
248
211
173
380
Lcia
206
195
214
283
288
212
288
264
233
193
158
349
UCLb
228
230
256
336
318
253
372
300
263
230
190
414
Carbon monoxide emissions, %
Arithmetic
mean
1.12
1.71
1.18
1.40
1.23
1.36
1.56
1.76
1.59
1.61
1.50
2.17
Geometric
mean
1.05
1.56
1.06
1.23
1.08
1.04
1.43
1.66
1.50
1.50
1.44
1.97
LCLa
0.88
1.28
0.89
1.06
0.98
0.89
1.22
1.49
1.32
1.25
1.26
1.71
UCLb
1.26
1.91
1.26
1.42
1.19
1.22
1.68
1.84
1.70
1.80
1.64
2.28
aLCL • lower confidence limit of 95 percent confidence interval on geometric mean.
UCL :Upper confidence limit of 95 percent confidence interval on geometric mean.
-------
Table 4. PERCENTAGE OF CARS WITH EMISSIONS EXCEEDING STANDARDS
(For all displacement groups with 15 or more tests)
m
O
CO
30
O
m
-o
33
O
Manufacturer
American Motors
Corporation
Chrysler
Corporation
Ford Motor
Company
General Motors
Corporation
Chevrolet
1968
1969
Pontiac
Volkswagen
CID
290
225
318
289
302
390
307
327
327
350
400
92
Tests on all cars
Number
tested
32
21
49
45
110
118
48
48
53
25
23
35
Average
odometer
reading
5,133
13,568
4,991
10,994
8,953
3,044
9,548
16,960
5,611
9,631
6,492
9,914
Cars with emissions
over standard, %
HC
0
14
12
62
58
16
60
42
10
16
0
31
CO
13
48
10
22
19
15
54
58
47
56
48
23
Both
0
14
4
20
19
8
42
29
4
8
0
9
Either
13
48
18
64
58
23
72
71
53
64
48
45
Tests on cars with more than 3,500 miles
Number
tested
24
20
28
44
95
72
36
48
32
21
21
30
Average
odometer
reading
6,157
14,178
8,125
11,191
10,038
12,461
12,040
16,960
8,354
1 1 ,236
7,061
1 1 ,537
Cars with emissions
over standard, %
HC
0
15
18
62
63
25
75
42
16
14
0
37
CO
8
45
14
23
20
24
56
58
44
62
52
20
Both
0
15
7
20
20
13
47
29
6
10
0
10
Either
8
45
25
65
63
36
84
71
54
66
52
47
-------
The average Ford 289- and 302-CID engines and the average Chevrolet
307-CID engines had HC emissions considerably in excess of Federal stan-
dards. The average 1968 Chevrolet 327-CID engine had HC emissions slightly
higher than the standards. Of the remaining displacement groups (with 15 or
more test vehicles), all had average HC values less than the limits imposed by
the Federal standards.
Although several of the displacement groups had average CO emissions
slightly higher than the standards, none of the averages was significantly
greater than the standard.
Results for the 14 engine-displacement groups represented by fewer than
15 test vehicles are presented in Tables 5 through 7. A sample smaller than 15
was considered too small to allow meaningful statements about average emis-
sions for the displacement group because the effect of random fluctuations on
data from such a small sample could be relatively large.
Estimates of the exhaust emissions of the population of domestic vehicles
were made by combining exhaust-emission data and the estimated production
percentages shown in Table 1. Foreign vehicles were excluded because only
Volkswagen data were obtained and the Volkswagen, because of its small
engine size, was subject to emission standards that were different from those
applicable to domestic vehicles. The distribution of HC and CO emissions is
shown respectively in Figures 1 and 2. Similar plots were made after data
obtained from vehicles with fewer than 3,500 miles were eliminated, but these
are not presented because they were almost identical in appearance to Figures
1 and 2. The data may be summarized as shown in Table 8.
As these data show, more than half of the vehicle population represented
by the test sample had exhaust emissions, at the mileage levels of the vehicles
sampled, below the limits prescribed in the Federal standards.
An attempt was made to estimate the change in emission levels with
mileage for each displacement group. The sample, however, was not well
suited to this type of analysis because most of the cars had accumulated
relatively few miles, ranging from a low of 29 to a high of 27,493, with an
average of only 7,708 miles. Past experience indicates, however, that vehicle
emissions increase with mileage accumulation. It is reasonable to conclude,
therefore, that although this study provides no basis for predicting emission
levels at 50,000 miles, many of the vehicles will have higher emission levels
when they have been driven 50,000 miles.
Results 13
-------
Table 5. MEAN EMISSION CONCENTRATIONS FOR ALL DISPLACEMENT GROUPS WITH LESS THAN 15 TESTS
Manufacturer
American Motors
Corporation
Chrysler
Corporation
Ford Motor
Company
General Motors
Corporation
Chevrolet
Pontiac
Oldsmobile
Cadillac
CID
343
383
440
200
351
429
460
462
230
350
428
350
455
472
Number
tested
12
7
3
11
13
8
5
5
5
5
4
4
8
8
Odometer readings
Average
3,846
3,050
3,883
741
4,397
11,013
4,221
11,910
5,060
12,704
5,089
4,155
13,255
6,300
Average of
minimum 2
1,593
478
2,873
32
1,275
6,129
3,735
6,936
3,368
3,827
2,328
2,377
10,208
652
Average of
maximum 2
6,130
5,096
4,704
3,156
6,904
15,806
4,813
15,757
7,303
21 ,628
7,852
5,934
16,234
11,494
Hydrocarbon emissions, ppm
Arithmetic
mean
203
212
217
212
210
215
186
203
185
214
324
187
138
146
Geometric
mean
201
207
214
211
209
196
178
197
183
212
319
186
137
145
LCLa
184
167
135
195
195
139
116
140
149
182
228
168
126
130
UCLb
220
257
341
228
224
276
273
278
225
248
448
206
149
163
Carbon monoxide emissions, %
Arithmetic
mean
0.94
1.17
0.89
1.07
0.83
1.76
1.42
1.51
1.37
1.95
2.72
2.34
2.09
1.08
Geometric
mean
0.90
1.08
0.88
1.05
0.74
1.60
1.28
1.50
1.32
1.93
2.68
2.31
2.07
1.08
LCLa
0.74
0.73
0.44
0.90
0.54
1.08
0.69
1.23
0.88
1.51
1.93
1.66
1.76
0.98
UCLb
1.10
1.61
1.76
1.35
1.00
2.36
2.36
1.83
1.98
2.46
3.73
3.23
3.10
1.19
m
I
CO
33
O
m
-o
30
O
O
•33
al_CL ; Lower confidence limit
bUCL : Upper confidence limit
of 95-percent confidence interval
of 95-percent confidence interval
on geometric mean.
on geometric mean.
-------
i?
en
Table 6. MEAN EMISSION CONCENTRATIONS FOR ALL DISPLACEMENT GROUPS WITH LESS THAN 15 TESTS
(Tests on vehicles with less than 3,500 miles eliminated)
Manufacturer
American Motors
Corporation
Chrysler
Corporation
Ford Motor
Company
General Motors
Corporation
Chevrolet
Pontiac
Oldsmobile
Cadillac
CID
343
383
440
200
351
429
460
462
230
350
428
350
455
472
Number
tested
8
4
2
1
9
8
5
4
4
4
3
3
8
6
Odometer readings
Average
4,827
4,360
4,704
4,903
5,627
11,013
4,221
14,169
5,628
15,124
6,498
5,323
13,255
8,183
Average of
minimum 2
4,039
3,625
4,704
4,903
4,085
6,129
3,735
12,582
3,954
8,622
5,700
4,135
10,208
4,974
Average of
maximum 2
6,130
.5,096
4,704
4,903
6,904
15,806
4,813
15,757
7,303
21 ,628
7,852
5,934
16,234
11,494
Hydrocarbon emissions, ppm
Arithmetic
mean
215
224
210
267
213
215
186
201
187
221
355
182
138
155
Geometric
mean
214
222
206
267
212
196
178
194
184
220
355
182
137
154
LCia
192
171
22
—
194
139
116
117
136
183
327
161
126
140
UCLb
238
287
1,928
—
231
276
273
322
249
263
385
205
149
170
Carbon monoxide emissions, %
Arithmetic
mean
1.03
1.15
0.94
1.10
0.88
1.76
1.42
1.52
1.42
1.97
2.96
2.20
2.09
1.09
Geometric
mean
0.99
1.07
0.92
1.10
0.83
1.60
1.28
1.50
1.35
1.93
2.96
2.17
2.07
1.09
LCLa
0.76
0.56
0.03
—
0.64
1.08
0.69
1.12
0.75
1.35
2.40
1.31
1.76
0.95
UCLb
1.29
2.07
27.90
_
1.09
2.36
2.36
2.02
2.44
2.78
3.65
3.60
2.43
1.25
LCL - Lower confidence limit of 95-percent confidence interval on geometric mean.
bUCL r Upper confidence limit of 95-percent confidence interval on geometric mean.
-------
Table 7. PERCENTAGE OF CARS WITH EMISSIONS EXCEEDING STANDARDS
(For all displacement groups with less than 15 tests)
m
I
o
oo
30
m
>
o
30
O
Manufacturer
American Motors
Corporation
Chrysler
Corporation
Ford Motor
Company
General Motors
Corporation
Chevrolet
Pontiac
Oldsmobile
Cadillac
CID
343
383
440
200
351
429
460
462
230
350
428
350
455
472
All tests
Number
tested
12
7
3
11
13
8
5
5
5
5
4
4
8
8
Average
odometer
reading
3,846
3,050
3,883
741
4,397
11,013
4,221
11,910
5,060
12,704
5,089
4,155
13,255
6,300
Cars with emissions
over standard, %
HC
0
14
0
0
0
13
0
0
0
0
76
0
0
0
CO
0
28
0
0
8
63
40
40
20
100
100
100
100
0
Both
0
0
0
0
0
13
0
0
0
0
76
0
0
0
Either
0
42
0
0
8
63
40
40
20
100
100
100
100
0
Tests on cars with more than 3,500 miles
Number
tested
8
4
2
1
9
8
5
4
4
4
3
3
8
6
Average
odometer
reading
4,827
4,360
4,704
4,903
5,627
11,013
4,221
14,169
5,628
15,124
6,498
5,323
13,255
8,183
Cars with emissions
over standard, %
HC
0
25
0
0
0
13
0
0
0
0
100
0
0
0
CO
0
25
0
0
11
63
40
50
25
100
100
100
100
0
Both
0
0
0
0
0
13
0
0
0
0
100
0
0
0
Either
0
50
0
0
11
63
40
50
25
100
100
100
100
0
-------
30
-------
Tables. DATA SUMMARY
Description of data
Cumulative % of
vehicle population
50.0
78.0
62.4
73.4
61.2
Production-weighted
means
Arithmetic mean
Antilog of mean log
Emissions from all
cars
HC,
ppm
216
275a
—
-
-
236
223
CO,
°/0
1.30
—
1.50a
-
-
1.41
1.25
Emissions from cars
with odometer
readings »3, 500 miles
HC,
ppm
226
—
-
275a
-
247
232
CO,
%
1.20
—
-
-
1.50a
1.45
1.29
aFederal standard.
18
RENTAL VEHICLE SURVEILLANCE PROGRAM
-------
SUMMARY AND CONCLUSIONS
Results of 705 exhaust-emission tests conducted on 1968- and 1969-
model-year rental vehicles by the Environmental Protection Agency's Bureau
of Mobile Source Pollution Control revealed the following:
1. Exhaust emission levels varied considerably among automobiles of
different manufacturers, among automobiles with different engine
types, and among different engines of the same type. Most types of
engines had emission levels below the limits imposed by Federal cer-
tification requirements.
2. The types of vehicles sampled in this survey represent about two-
thirds of the population of 1968 and 1969 domestic automobiles.
Approximately 75 percent of this population was projected to have
hydrocarbon emissions that were less than the levels prescribed by
the Federal certification standards, and approximately 60 percent had
carbon monoxide emissions that were less than the prescribed levels,
as determined by weighting test-vehicle percentages in proportion to
production of that type vehicle. No statement can be made con-
cerning compliance with standards by that portion of the population
not represented in the test sample.
3. Some engines produced by Ford and Chevrolet had particularly high
emission levels. More than 80 percent of the vehicles equipped with
Chevrolet 307-CID engines that had been driven at least 3,500 miles
produced either hydrocarbon or carbon monoxide emissions in excess
of Federal certification levels. The Ford 289- and 302-CID engines
also had high emission levels. These engines were used in a relatively
high percentage of the vehicles produced (estimated at over 16 per-
cent of total 1968 and 1969 domestic production, and over 24
percent of the population represented by vehicles tested in this
study).
4. Vehicles in the test sample had accumulated relatively few miles,
ranging from a low of 29 to a high of 27,493 miles, with an average
of 7,708 miles. Past experience with the real-life vehicle population
indicates that emissions increase with mileage accumulation. It is
reasonable, therefore, to project that a smaller percentage of the
vehicles represented in this test program will have exhaust emission
levels below the Federal limits when they have been operated 50,000
miles.
19
------- |