US. Department

of Transportation

National Highway

Traffic Safety

Administration

DOT HS 806 971 May 1986

NHTSA Technical Report

Fuel Economy and Annual Travel

for Passenger Cars and Light Trucks:

National On-Road Survey

This document is available to the public from the National Technical Information Service, Springfield, Virginia 22161.
Technical Report Documentation Page

1. Report No.

DOT HS 806 971

2. Government Accession No, 3. Recipient's Catalog No,

4. Title and Subtitle

Fuel Economy and Annual Travel for Passenger Cars and

Light Trucks: National On-Road Survey

5, Report Date

May 1986

6. Performing Organization Code

WPP-1 0

7. Author's)

Glenn G. Parsons

8. Performing Orgoniiotion Report No.

9. Performing Organization Nome and Address

Office of Standards Evaluation

National Highway Traffic Safety Administration

400 Seventh Street, S.W.

Washington, DC 20590

10. Work Unit No. (TRAIS)

11. Controct or Grant No.

12. Sponsoring Agency Name and Address

U.S. Department of Transportation

National Highway Traffic Safety Administration

400 Seventh Street, S.W.

Washington, DC 20590

13. Type of Report and Period Covered

NHTSA Technical Report

14. Sponsoring Agency Code

IS. Supplementary Notes

An agency staff review of existing Federal regulations performed'in compliance with

Executive Order 12291 and the agency's regulatory review plan (Regulatory Reform -

The Review Process, DOT HS-806-159, March 1982).

16. Abstroet One of the principal actions taken by the United States in response tcr~tfte~

worldwide energy crisis of the 1970's was to Federally mandate minimum fuel economy

standards for new motor vehicles. These standards began with the 1978 Model Year and

continue in force today. This study is an assessment of the reduced energy (fuel)

consumption for Model Year 1978-1981 vehicles, based on a national, on-road survey.

In addition to the Federal standards, rapid rises in fuel costs in that period

provided a second incentive for the production of more fuel efficient vehicles. The

study found that:

o From 1977 to 1981, on-road fuel economy of cars increased by 41 percent;

for light trucks, from 1978 to 1981, the increase was 17-26 percent.

o Fuel efficiency improvements in the 1978-1981 vehicles will reduce fuel

consumption by 45.6 billion gallons—a dollar equivalent reduction of

$53.8 billion.

o On-road fuel economy is consistently below laboratory (EPA) ratings,

ranging from 15-20 percent depending on vehicle type.

o Average annual travel per vehicle is about 6,000 miles; both per vehicle and

total fleet travel, based on odometer data, are markedly less than estimated

by prior surveys.

17. Key Words

Motor vehicle fuel economy, Federal fuel

economy standards, CAFE, on-road versus

laboratory mpg, statistical survey,

odometer readings, vehicle miles

traveled

18, Distribution Statement

Document is available to the public

through the National Technical Information

Service, Springfield, Virginia 22161

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21* No. of Pages

250

22. Price

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized

i

TABLE OF CONTENTS

Acknowledgments. xi

Executive Summary xiii

CHAPTER 1 INTRODUCTION 1

CHAPTER 2 ANALYSIS OF SURVEY RESULTS OF FUEL ECONOMY AND ESTIMATION

OF REDUCED ENERGY CONSUMPTION AND EQUIVALENT DOLLAR VALUE....10

2.1 Passenger Cars: On Road Fuel Economy 11

2.1.1 Reliability of On-Road Fuel Economy Estimates.... 15

2.1.2 On-Road Fuel Economy Versus CAFE ...18

2.1.3 On-Road Fuel Economy Compared to the

Federal Standards 20

2.1.4 On-Road Fuel Economy by Size Class 21

2.1.5 On-Road Fuel Economy by Manufacturer 21

2.2 Light Trucks - Two-Wheel Drive:

On-Road Fuel Economy 30

2.2.1 On-Road Fuel Economy Compared to EPA CAFE 34

2.2.2 On-Road Fuel Economy Compared to

Federal Standard 36

2.3 Light Trucks - Four-Wheel Drive: On-Road

Fuel Economy 37

2.4 Light Truck On-Road Fuel Economy by Size Class .39

2.5 Diesel izat ion 42

2.5.1 Effect of Dieselization on Fuel Economy 42

2.5.2 Diesel On-Road Fuel Economy Versus EPA

Laboratory Estimates 45

2.6 Seasonal Effect on Fuel Economy 48

2.7 Comparison of ORFES Results with Prior Studies of

on-Road Fuel Economy 52

2.7.1 Department of Energy Studies .52

2.7.2 Environmental Protection Agency Study 54

2.7.3 General Motors Study 55

2.7.4 Ford Motor Company Studies 57

2.7.5 Summary of ORFES Comparison with Other

On-Road Fuel Economy Studies 59

iii
2.8 Estimated Reduction in Fuel Consumption and

Equivalent Dollar Value 59

2.8.1 Reduced Fuel Consumption for Passenger Cars 60

2.8.2 Reduced Fuel Consumption for Light Trucks 69

2.8.3 Reduced Fuel Consumption, Light Vehicle Fleet....73

2.8.4 Discussion of Reduced Fuel Consumption

and Dollar Equivalent Estimates ....75

CHAPTER 3 ANALYSIS OF SURVEY RESULTS OF VEHICLE MILES TRAVELED 78

3.1 Methodology for Estimating Vehicle Miles Traveled 79

3.2 Vehicle Miles Traveled Estimates 83

3.2.1 Overall Estimates by Model Year and

Vehicle Type 83

3.2.2 Estimates by Size Class 90

3.2.3 Estimates by Type of Fuel 94

3.2.4 Annual VMT Estimates 97

3.2.5 Comparison of ORFES VMT Estimates with

Other Survey Estimates 108

CHAPTER 4 SURVEY METHODOLOGY AND DATA COLLECTION 115

4.1 Survey Design 116

4.1.1 Target Population and Sampling Frame 116

4.1.2 Sample Selection, Stratification, and

Division into Replicates 119

4.2 Questionnaire Design and Data Collection Methodology... 123

4.3 Data Collection, Processing, and Statistical

Estimation ....128

4.3.1 Receipt Control 128

4.3.2 Data Processing 130

4.3.3 Statistical Estimation 133

4.4 Survey Response and Nonresponse Issues 136

4.5 Potential Sources of Error in ORFES Statistics 140

4.5.1 Sampling Error 140

4.5.2 Nonsampling Error 141

iv
CHAPTER 5 PRINCIPAL SURVEY FINDINGS AND RESULTS 148

5.1 On-Road Fuel Economy Results - Passenger Cars 148

5.2 On-Road Fuel Economy Results - Light Trucks 149

5.3 On-Road Fuel Economy Compared to CAFE 151

5.4 On-Road Fuel Economy Compared to Federal Standards..... 152

5.5 Estimated Reduction in Energy Consumption and

Equivalent Dollar Value of More Fuel-Efficient

Vehicles 153

5.6 Estimates of Vehicle Miles Traveled 153

REFERENCES 157

APPENDIX A Listing of Vehicle Make Models Sampled in ORFES 160

APPENDIX B Estimation of Average Vehicle Age .< 202

APPENDIX C Survey Support Materials 205

(Prenotification Letter - NHTSA) 206

(Prenotification Letter - Survey Contractor) 207

(Questionnaire Transmittal Letter - First Wave). 208

(Incentive Log Booklet) 209

(Decals) 210

(Reminder Postcards) 211

(Questionnaire Transmittal Letter - Second Wave) 212

(Telephone Questionnaire) 213

(Questionnaire Transmittal Letter - Telephone Followup)... .217

APPENDIX D Methodology and Data for Estimating Reduced Energy

Consumption and Equivalent Dollar Value 228
LIST OF TABLES

Table 1-1 "Fuel Economy Standards for Passenger Cars and Light

Trucks for the 1978 through 1987 Model Years (in MPG) 3

Table 2-1 Passenger Car On-Road Fuel Economy and Comparison to

CAFE, Domestic and Import Fleets 12

Table 2-2 Standard Error and 95 Percent Confidence Intervals for

Passenger Car On-Road MPG .' 17

Table 2-3 Passenger Cars: Comparison of On-R-oad Fuel Economy

with CAFE and with Fuel Economy Standards 19

Table 2-4 Passenger Car On-Road Fuel Economy, Size Class by

Model Year 22

Table 2-5 Passenger Car On-Road Fuel Economy by Manufacturer

(Domestic) and Model Year.. 23

Table 2-6 Import Passenger Car Fleet - On-Road MPG by Manufacturer

and Model Year 24

Table 2-7 Domestic Passenger Car Fleet - Comparison of On-Road

MPG with CAFE, by Manufacturer 26

Table 2-8 Domestic Passenger Car Fleet - Comparison of On-Road

MPG with Federal Standard, by Manufacturer..... 27

Table 2-9 Import Passenger Car Fleet - Comparison of On-Road

MPG with CAFE, by Manufacturer 29

Table 2-10 Import Passenger Car Fleet -. Comparison of On-Road

MPG with Federal Standard Levels 31

Table 2-11 Light Truck On-Road Fuel Economy and Comparisons to

Cafe, Domestic and Import Fleets 32

Table 2-12 Light Truck: Two-Wheel Drive - Comparison of

On-Road Fuel Economy with CAFE and with Fuel Economy

Standards 35

Table 2-13 Light Truck: Four-Wheel Drive - Comparison of

On-Road Fuel Economy with CAFE and with Federal

Standards 38

Table 2-14 Light Truck On-Road Fuel Economy - Size Class by

Model Year 41

Table 2-15 Comparison of Fuel Economy (MPG) between Diesel and

Gasoline Powered Vehicles 43

Table 2-16 Diesel On-Road Fuel Economy Versus EPA Laboratory Estimates:

1981 Passenger Cars 47

vi
Table 2-17 On-Road Fuel Economy by Season of Year (Passenger Cars

Plus Light Trucks) 50

Table 2-18 Calendar Year Sales of Light Trucks, Model Years 1979-1981...69

Table 2-19(a) Total Reduction in Fuel Consumption and Dollar Equivalent

Value - Passenger Cars and Light Trucks, 74

Table 2-19(b) Per Vehicle Reduction in Fuel Consumption and Dollar

Equivalent Value - Passenger Cars and Light Trucks 74

Table 3-1 Total Average Vehicle Miles Traveled, as of July 1, 1983,

by Type of Vehicle and Model Year 83

Table 3-2 Standard Deviation and Standard Errors for VMT Estimates 85

Table 3-3 Ninety-five Percent Confidence Limits and Tolerance

Limits on VMT by Vehicle Model Year 88

Table 3-4 Total Vehicle Miles Traveled, Passenger Cars by Size Class....91

Table 3-5 Total Vehicle Miles Traveled, Light Trucks by Size Class 92

Table 3-6 Average VMT Rank by Size Class, Passenger Cars 93

Table 3-7 Vehicle Miles Traveled - Passenger Cars, Gasoline

Versus Diesel 95

Table 3-8 Total Vehicle Miles Traveled, Gasoline Versus Diesel,

Light Trucks 96

Table 3-9 Comparison of Observed and Predicted VMT 102

Table 3-10 Cumulative and Annual VMT Estimates Based on Fitted

Logarithmic Curve 105

Table 3-11 Data for Computation of Average Annual VMT, Entire

U.S. Fleet of Passenger Cars and Light Trucks 107

Table 3-12 Comparative Estimates of Average Annual Miles Traveled

Per Automobile by Age of Automobile 109

Table 4-1 States Not Sampled (Excluded from Sampling Frame) 119

Table 4-2 Sample Allocation Scheme, Cars and Station Wagons 122

Table 4-3 Sample Allocation Scheme, Trucks 123

Table 4-4 Locator File Disposition1 Codes 129

Table 4-5 Disposition Codes for Returned Questionnaires 130

Table 4-6 Final Dispositions for Total Sample (Based on Mail

Returns Only) 136

vii
Table D-1 Estimated Vehicle Miles, Lifetime, Passenger Cars 221

Table D-2 Estimated Vehicle Miles, Lifetime, Light Trucks 222

Table D-3 Estimated Average Price of Unleaded Gasoline, 1984 Dollars....226

Table D-4 Disount Factors for Estimating Present Value (1984 Dollars)

of Future Reduction in Fuel Consumption 227

viii
LIST OF FIGURES

Figure 2-1 Passenger Car On-Road Fuel Economy Versus CAFE and

Federal Standard 13

Figure 2-2 Light Truck (Two-Wheel Drive), On-Road Fuel Economy

Versus CAFE and Federal Standard 33

Figure 2-3 Light Truck (Four-Wheel Drive), On-Road Fuel Economy

Versus CAFE and Federal Standard 40

Figure 2-4 Seasonal Effect on Fuel Economy 51

Figure 3-1 ORFES Vehicle Miles Traveled by Model Year 98

Figure 3-2 Vehicle Miles Traveled Versus Vehicle Age, On-Road

Fuel Economy Survey, January-December 1983 100

Figure 4-1 Geographical Distribution of States Not Sampled

(Excluded from Sampling Frame) ". 120

Figure 4-2a On-The-Road Fuel Mileage Log (Questionnaire) 125

Figure 4-2b Reverse Side of Questionnaire 126

ix

ACKNOWLEDGMENTS

The author would like to express his appreciation to the staff at the

National Opinion Research Center (NORC) in Chicago and New York who worked

on the year-long data collection project with its complex schedule of

operations. Special acknowledgment goes to Jean Atkinson, on leave from the

British Office of Population Censuses and Surveys, who guided the NHTSA

survey project from Its initial design phase through most of the data

collection phase.

The author extends, a special note of gratitude to Alleyne Monkman of NHTSA's

Office of Standards Evaluation for her (typical) diligent and faithful

efforts in typing the manuscript.

EXECUTIVE SUMMARY

Over a decade has passed since the 1973 Arab oil embargo which presaged

a worldwide energy crisis. This initial shock was followed by several years

of tight fuel supplies and steadily rising energy prices which had major

impact on the U.S. economy as well as the economies of most other world

countries.

One of the actions taken in response to this energy problem in the

United States was the enactment of the Energy Policy and Conservation Act

(EPCA) in 1975 by the Congress. Among other steps taken by this Act, one

was aimed at energy conservation in the transportation sector through the

establishment of Federal Corporate Average Fuel Economy Standards for new

passenger cars and light trucks. Responsibility for administering this motor

vehicle fuel economy program was assigned to the Secretary of Transportation

who, in turn, delegated it to the Administrator of the National Highway

Traffic Safety Administration (NHTSA). Thus motor vehicle fuel economy

joined motor vehicle safety and other Federal regulatory programs

administered by NHTSA.

Fuel Economy Standards for passenger cars for the first three years

(1978-1980) and for 1985 and thereafter were originally set by the Congress

in the 1975 Energy Policy and Conservation Act. More recently, NHTSA, by

virtue of the statutory authority provided in the 1975 Act, amended the

passenger car standard for Model Year 1986. Also a notice of proposed

rulemaking (NPRM) has been issued concerning revision of the passenger car

standards for Model Years 1987 and 1988. Standards for light trucks have

been established for Model Year 1979 through Model Year 1988. All light

x i i i
truck standards have been set by NHTSA. Chapter 1, (Table 1-1) of this

report lists the individual fuel economy levels, in terms of miles per

gallon, as currently set by the standards.

This study is an assessment of the actual fuesl economy levels, and

reduction in energy consumption of the new, more fuel-efficient vehicles

produced from Model Year 1978 through 1981. It should be noted that, in

addition to the fuel economy standards (which took effect for passenger cars

in Model Year 1978 and for light trucks in Model Year 1979), consumer demand

and other market forces provided incentives for greater fuel economy during

that time period. This study does not attempt to determine what portion of

the improved fuel economy is attributable to the Federal standards.

A second major portion of this study develops estimates of annual

vehicle miles traveled (VMT) by age and type of vehicle (passenger car and

light truck) using vehicle odometer readings. It is believed that this is

the first time that estimates of VMT have been developed using actual

odometer readings from a large-scale national sample of the U.S. vehicle

fleet.

The study was conducted to comply both with Executive Order 12291

concerning the review of Federal regulations, and with NHTSA's regulatory

review plan published in March 1982 (Regulatory Reform - The Review

Process).

xiv
As with most of NHTSA's evaluation studies, data reflecting

"real-world" or "on-road" experience are used. The data come from a

specially conducted survey, using probability sampling methods, of the

Nation's fleet of privately owned and operated passenger cars and light

trucks. Vehicle owner/drivers provided fuel-mileage logs or diaries for

approximately 9,000 vehicles. Each log contained data on fuel purchases and

odometer readings for approximately a one-month period. The sample was

fielded in twelve monthly replicates throughout an entire one year period

in order to account for seasonal effects on fuel economy and on vehicle

travel.

This study is not an evaluation or assessment of official compliance

with the Federal fuel economy standards. The process by which official

compliance is determined was established via statute as part of the Energy

Policy and Conservation Act of 1975 which authorized the standards. For

each manufacturer, the Environmental Protection Agency (EPA) computes an

overall average fuel economy for each model year. This overall average fuel

economy (or miles per gallon) is based on laboratory measurements generated

by the EPA during its testing of vehicles for emissions levels and for

determining compliance with Federal emissions standards. Fuel economy

measurements are made for each basic vehicle type for each manufacturer and

a harmonically weighted average figure is calculated based on the number of

vehicles of each basic type sold by each manufacturer within each model

year. This overall fuel economy is thus a sales-weighted average and is

commonly referred to as the corporate average fuel economy, or "CAFE." It

is this CAFE which determines official compliance with the Federal fuel

economy standards.

-XV
While the laboratory results generated by the EPA provide a

standardized controllable, repeatable, convenient, and economical (i.e., the

production of fuel economy data as a byproduct of emissions testing was

already in place prior to enactment of the ECPA in 1975) method of assessing

manufacturer progress vis-a-vis the Federal standards, it has nonetheless

been well established by several prior studies1 that laboratory tests do not

necessarily reflect fuel economy under typical, everyday driving conditions;

laboratory results are typically higher than actual on-road fuel economy.2

Also as has been noted previously, it has been the policy of NHTSA to

utilize data reflecting actual "on-road" experience, wherever feasible in

its studies of the effects of its programs and motor vehicle regulations.

The general objectives of this study are to:

(1) Estimate the on-road fuel economy improvements for passenger

cars and light trucks produced from the beginning of fuel

economy standards through Model Year 1981.

(2) Compare the on-road fuel economy with the respective

laboratory-based, or corporate average fuel economy (CAFE)

levels as computed by the Environmental Protection Agency

and as specified in the Energy Policy and Conservation Act of

1975.

1 These studies have been done'both by other Federal agencies and by companies

within the motor vehicle industry. The results of these studies are

discussed later in this report.

2 Largely as a consequence of this situation, the EPA has recently begun

discounting its laboratory data on fuel economy which are displayed on

"window stickers" of new motor vehicles and which are published in the EPA

annual consumer booklet, "Gas Mileage Guide."

xvi
(3) Compare the on-road fuel economy with the levels set by the

respective Federal Fuel Economy Standards. ..-••

(4) Estimate the reduction in energy (fuel) consumption, and

dollar equivalent value, for vehicles produced from Model

Year 1978 through Model Year 1981.

(5) Estimate annual vehicle miles traveled by the U.S. fleets of

passenger cars and light trucks, by age of the vehicle and

overall average per vehicle.

FINDINGS AND CONCLUSIONS

Following are the principal findings and conclusions reached in this

study:

(1) On-Road Fuel Economy of Passenger Cars

a. From Model Year 1978 through 1981, the on-road

fuel economy of the U.S. fleet of passenger cars

increased by 41 percent, rising from 15.2 mpg in Model

Year 1977 to 21.4 mpg in Model Year 1981.

b. The greater portion of this gain in fuel economy is

attributed to the domestic fleet (39 percent gain)

compared to the import fleet (13 percent gain). This

is to be expected considering the large differences in

the original size and fuel economy of the two fleets

xvi i
prior to promulgation of the standards, and prior to

the significant increase in fuel prices following the

"second oil shock" of 1979.

c. Among domestic manufacturers, overall fuel economy

gains for the four model year period ranged from a low

of 25 percent for American Motors to a high of 70

percent for Chrysler, which had a large jump of nearly

6 mpg from Model Year 1980 to Model Year 1981.

d. Gains among foreign manufacturers were modest except

for Volkswagen's 30 percent increase, from the 1977 to

1981 models, attributable to a large penetration of

diesel vehicles.

(2) On-Road Fuel Economy of Light Trucks

a. From Model Year 1979 through 1981, on-road fuel

economy increased by 26 percent (13.4 mpg to 16.9 mpg)

for 2-wheel drive vehicles; for 4-wheel drive trucks,

the increase was 17 percent (12.3 mpg to 14.4 mpg).

xviii
b. As was true for passenger cars, fuel economy gains

were greater for domestic vehicles. The relative

gains from 1978 to 1981 model fleets were:

2-wheel drive Change in MPG

domestic trucks: +21% mpg

import trucks: +9* mpg

4-wheel drive

domestic trucks: +9% mpg

import trucks: +495 mpg'

(3) On-Road Fuel Economy Compared to Laboratory-based (EPA) CAFE*

a. For the model years surveyed, on-roa'd fuel

economy is consistently below laboratory-based CAFE

levels. For passenger cars the difference is 15

percent; for 2-wheel drive trucks, 16 percent; for

4-wheel drive trucks, almost 20 percent.

3 1980 to 1981 increase

4 It should be noted that the EPA recently issued a final rule (50 FR 27172,

July 1, 1985) adjusting its fuel economy measurements for Model Year 1980

and later, to account for test procedure changes. While this information

was not available at the time this study was written, the effect of this EPA

adjustment is to increase somewhat the differences between EPA CAFE values

and on-road fuel economy, as estimated in this study, for Model Years 1980

and 1981.

xix
b. Except for 4-wheel drive trucks, domestic vehicles

exhibited a somewhat greater difference than import

vehicles.

c. The CAFE to on-road difference among domestic

manufacturers was approximately the same with AMC and

Chrysler showing slightly less difference than GM and

Ford.

d. Among import vehicles, the greatest CAFE to on-road

difference was noted for the captive imports of Ford

and Chrysler. Only one manufacturer, Volkswagen, had

an on-road mpg consistently at or above its CAFE.

e. This finding that on-road fuel economy is consistently

below laboratory-based CAFE is not new. It has been

shown in several prior studies although the data

bases used and the magnitudes of the CAFE to on-road

differences found have differed somewhat from those in

this study. This study is believed to be the first

which develops on-road fuel economy estimates from a

nationwide, large-scale probability sample.of the

total national population of privately-owned vehicles.

XX
(4) On-Road Fuel Economy Compared to Federal Fuel Economy

Standards

a. For the three categories of vehicles, passenger cars,

two-wheel drive trucks, and four-wheel drive trucks,

the on-road fuel economy ranges from 8 to 9 percent

below the Federal standard levels for Model Years

1978-1979; for 1980-1981, on-road mpg is much closer

to the standard levels and in some instances, slightly

above.

b. Domestic vehicle on-road mpg is approximately 10

percent below the Federal standards; import vehicle

on-road mpg ranges from 20 to 45 percent above the

Federal standards. As stated earlier, this is

primarily due to the smaller average size of import

vehicles compared to the average size of domestic

vehicles. Relative fuel economy gains were greater

for domestics than for imports.

(It should be noted, as previously stated, that

compliance with the Federal standards is determined

through laboratory testing by the Environmental

Protection Agency. All vehicles, both import and

domestic, complied with the Federal Standards during

the study period).

XXI
(5) Estimated Reduction in Energy Consumption and Dollar

Equivalent Value

a. Estimated, vehicle lifetime, reduction in energy

consumption and dollar equivalent value (in 1984

dollars) for all vehicles (cars and trucks)

manufactured under the Federal standards through Model

Year 1981 are:

Reduced Fuel

Consumption Dollar Value

Total 45.6 billion gallons $53.8 billion

(All vehicles) (1.1 billion barrels)

Per

Vehicle 974 gallons $1,146

The baseline periods for these estimates are Model

Year 1977, for passenger cars, and Model Year 1978,

for light trucks.

Costs of implementing the Federal fuel economy

standards were not estimated for reasons described in

the report.

xxn
6. Vehicle Miles Traveled

An analysis of odometer readings for the approximately 9,000

vehicles covered in the survey gave the following estimates

concerning vehicle miles of travel by the Nation's population

of privately owned vehicles:

a. Average annual miles of travel for passenger cars and

light trucks is essentially the same — approximately

6,000 miles per year for the average vehicle.

b. Average annual miles of travel show little differences

of a practical nature between classes of vehicle

(e.g., small versus large car; 2-wheel drive versus

4-wheel drive truck, etc.).

c. Average annual miles of travel per vehicle shows a

sharp decline with vehicle age. First year travel is

estimated at 14,000 miles, but by the fifth year of

age, travel drops to less than half, or about 6,500

miles.

d. Total miles traveled was found to be considerably

higher for diesel vehicles than for conventionally

powered gasoline vehicles. This difference was more

pronounced for passenger cars than for light trucks.

Also, in contrast to the finding for the overall

fleet, vehicle size appeared to be an important factor

xx i i i
here as well, with small diesel powered vehicles

showing a greater increase in miles driven over their

gasoline powered counterparts, than large diesel

powered vehicles.

e. Average annual travel estimates from the On-Road

Survey are similar to estimates of other prior

surveys for the initial few years of vehicle life.

For later years, however, the On-Road results show a

much greater rate of decline in average annual travel

than prior surveys.

f. Results from the On-Road Survey indicate that average

annual travel per passenger car or light truck, and

total travel for all vehicles may be substantially

lower than heretofore estimated. Although fleet and

business use vehicles were not Included in the survey,

travel by this class of vehicles does not appear to be

of sufficient magnitude to account for the lower VMT

(vehicle miles traveled) findings in this study.

This is believed to be the first study to develop VMT

estimates from odometer readings of a large national

probability sample of the Nation's population of privately

owned passenger cars and light trucks.

XXIV
CHAPTER 1

INTRODUCTION

This is one of the continuing series of studies that have been

conducted by the National Highway Traffic Safety Administration (NHTSA) to

review and evaluate the effects of existing Federal regulations and programs

for which the Agency is responsible. Following the issuance of Executive

Order 12291 on February 17, 1981, the NHTSA developed and published a

regulatory review plan1 which contained a description of those regulations

selected for review together with a schedule for the conduct of the

individual reviews. The Automotive Fuel Economy Program was listed in that

review plan under the category of "moderate to high" priority.

The purpose of the Automotive Fuel Economy Regulations was to conserve

petroleum energy through the production of more fuel efficient motor

vehicles. These regulations were authorized under the Energy Policy and

Conservation Act of 19752 which grew out of the Arab oil embargo of late

1973. The fuel economy regulations, along with other parts of the Energy

Policy and Conservation Act, were part of a concerted National effort to

reduce energy consumption in the face of suddenly scarce petroleum supplies

and skyrocketing prices which grew out of the Arab oil embargo.

^ "Regulatory Reform - The Review Process," U.S. Department of Transportation,

National Highway Traffic Safety Administration, March 1982 (DOT HS-806-159).

2 Public Law 94-163, Title III, "Improving Energy Efficiency." This section

of the legislation amended the existing Motor Vehicle Information and Cost

Savings Act through the addition of Title V, "Improving Automobile

Efficiency. It is this latter portion of legislation which authorized the

development and implementation of a multi-year program (i.e., the

promulgation of Federal fuel economy standards) to improve the fuel economy

or passenger cars and light trucks sold in the United States.
The Energy Policy and Conservation Act assigned the responsibility for

administering the fuel economy program to the Secretary of Transportation,

who, in turn, delegated this responsibility to the Administrator of the

National Highway Traffic Safety Administration on June 22, 1976 (A1 F.R.

25015).

NHTSA's responsibilities, under the Act, include:

(1) establishing average fuel economy standards for manufacturers

of passenger automobiles and light trucks,

(2) promulgating .regulations concerning procedures, definitions,

and reports necessary to support the "fuel economy standards,

(3) considering petitions for exemption from established fuel

economy standards by low-volume manufacturers (e.g., those

whose total production is less than 10,000 vehicles

annually), and establishing alternative standards for these

manufacturers,

(A) reporting annually to Congress on the progress of the fuel

economy program,

(5) enforcing the fuel economy standards and regulations, and

(6) responding to petitions concerning domestic production by

foreign manufacturers and other matters.
The fuel economy standards that have been established through 1986

appear in Table 1-1.

TABLE 1-1

Fuel Economy Standards for Passenger Cars and Light Trucks

for the 1978 through 1987 Model Years (in MPG)

Model

Year

1978

1979d

1980e

1981*

1982

1983

1984

1985

1986

1987

Passenger

Cars - MPG

18.0c

19.0c

20.0c

22.0

24.0

26.0

27.0

27.5C

26.0f

27.5C> 9

Two-Wheel

Drive

17.2

16.0

16.7

18.0

19.5

20.3

19.7

20.5

21 .0

Light Trucksa

MPG

Four-Wheel

Drive

-Not Establlshed15.8

14.0

15.0

16.0

17.5

18.5

18.9

19.5

19.5

Composite13

17.2

17.5

19.0

20.0

19.5

20.0

20.5

a - Standards for 1979 model year light trucks were established for vehicles

with a gross vehicle weight rating (GVWR) of 6000 lbs. or less. Standards

for MY's 1980 through 1985 are for light trucks with a GVWR of up to 8,500

lbs.

b - For model years 1982-1986 manufacturers may comply with the two-wheel and

four-wheel drive standards or may combine their two-wheel and four-wheel

drive light trucks and comply with the combined standard.

c - Established by Congress in the Energy Policy and Conservation Act of 1975.

d - For MY 1979, light truck manufacturers may comply separately with standards

for four-wheel drive, general utility vehicles and all other light trucks,

or combine their trucks into a single fleet and comply with the 17.2 mpg

standard.

e - Light trucks manufactured by a manufacturer whose fleet is powered

exclusively by basic engines which are not also used in passenger automobiles, must meet standards of 14 mpg and 14.5 mpg in model years 1980 and

1981, respectively.

f - The Energy Policy and Conservation Act of 1975 originally established a

standard of 27.5 mpg for 1985 and subsequent years, but also provided the

Department of Transportation with authority to amend that standard. In

October 1985, NHTSA issued a final rule which changed the 1986 standard to

26.0 mpg.

g - For Model Year 1987 and subsequent years. (Rulemaking action is presently

pending which would revise the standards for Model Years 1987 and 1988).

Sources: "Automotive Fuel Economy Program, Seventh Annual Report to

Congress," U.S. Department of Transportation, National Highway

Traffic Safety Administration, January 1983.

"49 FR 41250," October 22, 1984
It should be noted that the standards began in 1978 for passenger cars and

in 1979 for light trucks; also to be noted is that certain standard levels

for passenger cars were "pre-established" by the Congress as part of the

authorizing legislation of 1975, whereas all remaining standard levels for

passenger cars and all standards for light trucks were the responsibility of

the Department of Transportation (DOT). Within certain guidelines, the Act

also provided the DOT with the authority to revise pre-set standard levels

for future model years, should such revision be deemed appropriate.

This study addresses the actual, on-road reduction energy, or fuel,

consumption for the U.S. fleet of passenger cars and light trucks produced

from the beginning years (1978 for passenger cars; 1979 for light trucks) of

the fuel economy standards through 1981. The study deviates, somewhat, from

the typical NHTSA evaluation study, or review, of a major regulation or

safety program where the primary focus is to estimate the effectiveness, or

benefits, attributable to that program and to compare these benefits to the

costs of Implementing the program. There are two reasons why the

conventional approach to program evaluation was not employed in this study.

First, although original plans called for estimation of costs of

implementing the Federal fuel economy regulations, subsequent budgetary and

program changes precluded the execution of this part of the evaluation

effort. In addition, it was recognized that the pervasive scope and complex

nature of the changes made within the motor vehicle industry in the drive

for greater fuel efficiency would make the estimation of the costs of

implementing the regulations difficult indeed. In addition to specific

technological developments such as diesel engines and improved
.transmissions, essentially all major domestic carline's were redesigned and

"downsized"; the use of front-wheel drive became widespread. It would have

been extremely difficult to attribute, objectively, the cost of such

comprehensive changes to the goal of increased fuel economy, vis-a-vis other

goals such as styling changes, improvements in vehicle quality and

reliability, etc. It is not difficult, therefore, to see that the isolation

of the costs of implementing the fuel economy regulations would be a task of

emminently greater complexity than the estimation of costs for motor vehicle

safety'standards such as side door beams, energy absorbing steering

assemblies, or fuel system integrity improvements, whose costs have been

estimated as parts of prior NHTSA evaluation studies.

A second reason complicating the traditional benefits versus costs3

approach to this study was that it would be difficult to attribute the

reduced fuel consumption of the vehicles produced subsequent to the

effective dates of the fuel economy standards to the standards themselves.

In addition to the Federal requirements to manufacture vehicles with better

fuel economy, there was also a second incentive in the form of increased

market or consumer demand for such vehicles, since gasoline prices had

increased dramatically during the 1970's and early 1980's.

While the cost effectiveness of the CAFE standards per se have not been

evaluated, NHTSA, as part of its Regulatory Impact Analysis of each CAFE

standard promulgated, has analyzed the cost effectiveness of the fuel

efficiency improvements available at that time to the manufacturers. The

cost effectiveness of fuel efficiency improvements is defined as the

estimated retail price increase to consumers, of the vehicle changes, versus

the present discounted value of fuel saved over the vehicle's lifetime.

These analyses showed that cost-effective fuel efficiency improvements were

available.

These analyses were "before the fact" (i.e., conducted prior to the actual

production and sale of the vehicle) whereas the analysis in this study is

after the fact, covering vehicles that are on the road and that have

generated real-world experience.
As is true for most NHTSA evaluation studies,.emphasis is placed on

assessing the effects of agency regulations, in this case, fuel economy

regulations, through the collection and analysis of real-world data. The

data for this study was gathered through a nationwide, on-the-road survey of

the fuel economy experienced by the U.S. fleet of Model Year 1977 through

1981 passenger cars and light trucks. The target population was also

defined as those vehicles manufactured by the four major domestic companies

and the four major foreign companies (Datsun/Nlssan, Honda, Toyota, and

Volkswagen) and was restricted to vehicles owned by private individuals

(i.e., fleet vehicles excluded). The survey was based on a national

probability sample with the sampling frame being the national vehicle

registration files maintained by the R. L. Polk Company. The sample was

stratified by model year of vehicle, vehicle type (passenger car, light

truck) vehicle size class (subcompact, compact, midsize, etc.), fuel type

(gasoline, diesel), and, for light trucks only, the number of drive wheels

(two-wheel drive, four-wheel drive). The final sample included 100 strata.

Allocation of the sample among strata for each model year and vehicle type

was made on a proportional basis with oversampling employed in a few

instances for rare strata in order to obtain reasonable subsample sizes in

the final sample. Allocation of the sample, within each stratum was also

made on a proportional basis among all of the individual vehicle make model

combinations comprising each stratum. Over 800 different vehicle make

models (i.e., 1961 Oldsmobile Cutlass diesel, 1981 Ford Escort, etc.) appear

in the final respondent sample (see Appendix A). The total sample was

subdivided into twelve equal replicates with one replicate being fielded for

each month of the data collection period, Calendar Year 1983. This
distribution over a 12-month period provided control over the seasonal

effect on fuel economy and vehicle miles traveled. Each vehicle stratum was

distributed equally within each of the 12 replicates.

The methodology for carrying out the survey consisted of mailing a

request to owners of sampled vehicles to maintain a record or diary4, of

their fuel purchases and respective odometer readings over a specified,

1-month period. To enhance survey response, the record-keeping request was

preceded by an advance notification letter, and accompanied by a small

incentive in the form of a log-booklet for the respondents' personal use

plus "reminder decals." Two follow-up "reminder" postcards were also sent,

one shortly after the mailing of the log-questionnaire and the second at the

end of the survey month to remind the respondent to return the completed

survey log. A second wave of mailings, including the questionnaire letter

and reminder postcards, were sent to all sampled owners who failed to

respond to the initial survey wave. Finally, telephone followup samples

were taken to investigate the potential effect of nonresponse and to assess

the potential for the telephone to enhance basic survey response. A more

detailed discussion of the survey methodology is given in Chapter 4.

The data collection and data automation phases of the On-Road Fuel

Economy Survey (ORFES) were conducted for NHTSA by a survey contractor.*

The contractor also provided certain computations and tabulations from the

data as well as completing a report on potential effects of survey

nonresponse.

* See Chapter A for a specimen of the survey instrument and Appendix C

for other survey materials.

5 "On-the-Road Fuel Economy Survey - Final Data Collection Report", submitted

to NHTSA, Office of Program Evaluation, by National Opinion Research Center,

October 1984.
The initial total sample of vehicles selected from the "Polk" sampling

frame was 46,000. Out of this, a total of 8,914 vehicles were represented

on the final survey analysis data file for a conservatively estimated

response rate of 21 percent. However, when the results of the two telephone

samples are considered together with the definition of eligible respondents

as agreed upon by the Council of American Survey Research Organizations6,

the effective response rate is in the vicinity of 35-40 percent. Survey

response as well as explanations of the data automation procedures, quality

control, etc., are also presented in Chapter 4.

Although the original primary objective of the ORFES was to estimate

on-road fuel economy, it was recognized that the survey would provide a

large sample of actual vehicle odometer readings from which estimates of

vehicle miles traveled could be developed. Data on vehicle miles traveled

are also of considerable interest to NHTSA, as well as several other

agencies. Thus a second important area covered in this report is the estimation of annual vehicle miles of travel by age of vehicle, by passenger car

and light truck, and by vehicle size class. These estimates are compared

with vehicle miles traveled estimates from prior known surveys and studies.

This report is presented in the four chapters which follow. Chapter 2

contains the results on fuel economy as measured in the on-road survey. In

this chapter, comparisons are also made between the on-road fuel economy and

6 See Chapter 4, Section 4.4.
respective EPA CAFE7 numbers and between on-road fuel economy and the

Federal standards. Also in Chapter 2, the effect of seasonallty and certai.fl

vehicle technologies on in-use fuel economy are analyzed. Thirdly, this

chapter contains a comparison of the ORFES on-road results with several

prior studies of on-road fuel economy. Chapter 2 concludes with an analysis

of the reduction in energy (fuel) consumption, and dollar equivalent value

for the vehicle fleet produced subsequent to enactment of the Federal

standards up through Model Year 1981. Chapter 3 contains the results of the

vehicle miles traveled estimates as developed from the survey data on

odometers and compares the ORFES estimates with those of prior studies and

surveys of vehicle miles traveled. Chapter 4 describes the survey design

data collection, data automation, survey response and nonresponse analysis.

Chapter 5 summarizes the primary findings and results from an analysis of

the survey data as it relates to fuel economy and vehicle miles traveled.

7 CAFE or Corporate Average Fuel Economy as defined in the Energy Policy and

Conservation Act of 1975, is that number which is used to determine each

manufacturer's compliance, for a given model year, with the Federal fuel

economy standard for that year. The CAFE is a number which is the

sales-weighted harmonic mean of the fuel economy (mpg) of all individual

basic vehicle types produced by a manufacturer in a given model year and Is

computed by the Environmental Protection Agency based on its laboratory

tests of new vehicles for purposes of determining compliance with Federal

emissions standards.
CHAPTER 2

ANALYSIS OF SURVEY RESULTS OF FUEL ECONOMY AND ESTIMATION

OF REDUCED ENERGY CONSUMPTION AND EQUIVALENT DOLLAR VALUE

2.0 INTRODUCTION

This chapter contains the analysis and summary of the fuel economy

results as reported by vehicle owners/drivers in the nationwide On-The-Road

Survey. Chapters 1 and A contain descriptions of the survey design and

methodology, survey Instrument and materials, data collection, data

automation and quality control, survey response, and nonresponse/noncoverage

effects.

All fuel economy estimates presented In this chapter, except where

otherwise noted, are harmonically weighted means1 using, as the weights,

actual nationwide counts of vehicles on the road as compiled,from national

vehicle registration files.2 These estimates are analogous to the

harmonically weighted means using sales data, as specified in the Energy

Policy and Conservation Act of 1975, which established the Federal Fuel

Economy Standards Program for passenger cars and light trucks.

1 See Chapter 1, footnote 7.

2 Vehicle counts are taken from the files compiled by the R. L. Polk Company

as of July 1, 1962, the latest data available when the analyses of data were

initiated.

10
The on-road fuel economy results are presented by type of vehicle

(passenger car, light truck); vehicle origin of manufacture (domestic,

import); vehicle manufacturer3; and vehicle size class (essentially

corresponding to EPA size class). Data are also presented to compare fuel

economy between gasoline and diesel powered vehicles.

Secondly, comparisons are made between on-road fuel economy and

laboratory based (EPA) corporate average fuel economy (CAFE) levels, and

between on-road fuel economy and the applicable Federal standard levels.

~ Third, and lastly, estimates of the total reduction in energy

(fuel) consumption are made for the vehicles represented in the survey, both

on an overall vehicle lifetime basis, and on a per vehicle (lifetime) basis.

Estimated dollar equivalent values of the reduced consumption are also

developed.

2.1 PASSENGER CARS: ON-ROAD FUEL ECONOMY

Table 2-1 displays the on-road fuel economy for passenger cars for

the 5 model years covered by the survey. Data are shown for both the

Domestic'Fleet, the Import Fleet and the overall or combined U.S. Fleet.

Also presented are the respective EPA CAFE's and the Federal Fuel Economy

Standards for the 4 years, 1978 through 1981. Figure 2-1 displays the trend

in on-road, EPA CAFE, and standard values by model year.

The survey included all four major domestic manufacturers (including their

captive imports, as appropriate), plus the four major foreign manufacturers

(Datsun/Nissan, Honda, Toyota and Volkswagen).

11
TABLE 2-1

PASSENGER CAR ON ROAD FUEL ECONOMY

AND COMPARISON TO EPA CAFE

- DOMESTIC AND IMPORT FLEETS -

FLEET

Miles per Gallon for Model Year:

1977 1978 1979 1980 1981

Domestic

On-Road

EPA CAFE

Import

EPA On-Road

CAFE4

Overall On-Road

Overall EPA CAFE5

Fuel Economy

Standard

U .5

N/A

23.7

N/A

15.2

18.6

N/A

15.7

18,7

24.6

28.7

16.6

19.9

16.0

16.5

19.3

25.0

27.2

17.3

20.3

19.0

18.6

21. B

26.7

29.7

20.0

23.4

20.0

20.2

23.6

26.7

31.4

21.4

25.2

22.0

NOTE 1: Sample sizes (i.e., number of vehicles reporting in the national

survey) ranged from 109 to 1,527 for each of the ten subgroups in

the above table.

NOTE 2: The above EPA CAFE values were correct at the time this study was

written. However, it should be noted that the EPA recently Issued

a final rule (50 FR 27171, July 1, 1965) which adjusted (upward)

its fuel economy measurements for Model Year 1980 and later, to

account for changes in test procedures. The effect of this EPA

revision Is to increase, somewhat, the above CAFE's for Model Years

1980 and 1981, and thereby increasing the amounts of CAFE to

on-road differences as estimated in this study.

CAFE for six import manufacturers included in survey: Datsun/Nissan, Honda,

Toyota, Volkswagen, and two captive import groups, Chrysler and Ford.

CAFE for all import manufacturers, Including captive imports for Chrysler

and Ford.

12

As the table shows, the overall (i.e., total fleet) on-road fuel

economy shows a steady improvement over the base 1977 Model Year from 15.2

miles per gallon (mpg), to 21.4 mpg for the 1961 Model Year. This represents a total increase in fuel economy of 6.2 mpg or 41 percent over four

model years. The yearly, average increase amounts to approximately 10

percent or 1.55 mpg. The major portion of this increase can be attributed

to vehicles produced in the U.S. which saw an overall increase in fuel

economy of approximately 40 percent, compared to an increase of 13 percent

for the imports. Of course, it must be remembered that prior to enactment

of the fuel economy regulations, the mpg was considerably higher for the

imports than for domestically manufactured cars; import fleet mpg for the

base year was nearly 60 percent higher than domestic fleet mpg. Consequently, the impetus for import manufacturers to raise mpg was less since

their base year mpg was already higher than the fuel economy regulations

called for, even as late as 1981.

One qualifying comment should be noted in the above discussion of

the fuel economy improvements. Nineteen seventy-eight was the initial year

of the Federal Fuel Economy Regulations, and therefore, 1977 is taken as the

base year on which to compute fuel economy gains. However, the first

significant step to increase passenger car fuel efficiency came in the 1977

model year when General Motors downsized its standard-sized cars and

standard-sized station wagons. Based on registration data, the GM standard

size cars accounted for approximately 20 percent of the U.S. domestic fleet

of 1977 passenger cars. Therefore, it may be stated that the above

estimates of total fuel efficiency gains are somewhat conservative since

they do not include that portion of the gain resulting from the downsizing
of the 1977 GM standard size cars. As noted previously, Model Year 1977 was

the earliest year covered by the survey and thus the actual Incremental

savings attributable to the downsized GM standard vehicles cannot be

measured with the available data.

2.1.1 RELIABILITY OF ON-ROAD FUEL ECONOMY ESTIMATES

In statistical surveys such as the On-Road Fuel Economy Survey, it

is typically of Interest to estimate not only the mean values for certain

population parameters — in this case, on-road fuel economy or mpg—but also

to evaluate the reliability of these estimates. Reliability here is defined

as the degree of precision which can be attached to the various mean

estimates.

The standard method of measurement of precision in statistical

surveys is the standard error which in the simple case'is the sample

standard deviation, s, divided by the square root of the sample size, or n.

Table 2-2 contains standard error estimates for each of the overall model

year (e.g., domestic plus import) estimates of on-road mpg as given in Table

2-1. The standard errors for each model year are estimated from the

formula:

SE(Model Year) =

15
where,

SEn =

 s/S/n s standard error for each stratum in the sample or

each vehicle size class within a given model

year.

and Wh c weighting factor corresponding to the proportion of the

total vehicle population in the stratum/size class

relative to the total vehicle population for the given

model year.

Also given in the table are the 95 percent confidence intervals

for the mean estimates for each model year. The interpretation for each of

these intervals is that in repeated sample surveys such as this, 95 percent

of intervals so constructed would contain the true population mean or the

true on-road mpg for the particular model year.

16
TABLE 2-2

STANDARD ERROR AND 95 PERCENT CONFIDENCE INTERVALS

FOR PASSENGER CAR ON-ROAD MPG

Model

Year

1977

1978

1979

I960

1981

Sample

Size

B55

1, 129

1,380

1,570

2.1U

On-Road

MPG (Mean)

15.2

16.6

17.3

20.0

21.A

Standard

Error (MPG)*

0.157

0.U5

0.184

0.132

0.120

Relative

Standard

Error (%)

1.0

0.9

1.1

0.7

0.6

95 Percent

Confidence

Interval (MPG)»

14.9 - 15.5

16.3 - 16.9

16.9 - 17.7

19.7 - 20.3

21.2 - 21.6

•It will be recalled that the mean mpg has been calculated using the

harmonic formula since this was the method specified in the Energy Policy

and Conservation Act which established the CAFE standards. The standard

errors in the above table however, have been computed on the basis of a

regular arithmetic mean due to the general lack of computerized statistical algorithms to handle standard errors for harmonic means. (It has

for years been nearly universal in the fields of analytical and survey

statistics to utilize the arithmetic mean rather than the harmonic mean

as a measure of central tendency.) Since it can be shown that the

harmonic mean, in the general case, is slightly less than the arithmetic

mean, it follows that an "arithmetic standard error" will be slightly

less than a "harmonic standard error." This is due to the fact that the

standard error is a function of > **^ - x) 2 , or the sum of squares

of the deviations of the sample mean from each individual sample

observation. Also confidence intervals constructed from arithmetic

standard errors will be slightly more narrow than similar intervals based

on harmonic standard errors. However, the magnitude of such differences

will be quite small for the data collected in the On-Road Survey and

hence the estimates given in the above table will be very close to the

values that would be obtained based on "harmonic standard errors."

17
It can be seen that the magnitude of the standard error does not

differ appreciably among the five model years, ranging from 0.12 to 0.18.

Relative to the mean however, it is seen that the error does tend to

decrease with the later model years.

2.1.2 ON-ROAO FUEL ECONOMY VERSUS EPA CAFE

Table 2-3 compares the results from the On-Road Survey with the

CAFE (as based on EPA test data) and with the Federal Fuel Economy Standards

for the years 1978-1981.

For the domestic cars, the on-road experience is consistently

below respective EPA CAFE levels by about 15 percent. On an absolute, or

mpg basis, the difference is somewhat larger in 1981 than in the period

1978-1980, rising to 3.4 mpg from about 3.0 mpg. This is to be expected if

the relative difference is essentially constant over the 4 years since both

the on-road and EPA CAFE levels show continual increases.

For imported cars, the on-road fuel economy is closer to the EPA

CAFE than for the domestic vehicles. No clear trend Is evident here,

however, since the on-road mpg is 14 to 15 percent lower-than the EPA CAFE

for Model Years 1978 and 1981, but only 8 to 10 percent, for the intervening

years 1979 and 1978. On an absolute basis, import on-road mpg is below the

EPA CAFE, ranging from approximately 2 to 5 mpg less. Again no distinct

trend is evident.

18
TABLE 2-3

PASSENGER CARS:

COMPARISON OF ON-ROAD FUEL ECONOMY WITH EPA CAFE

AND WITH FUEL ECONOMY STANDARDS

COMPARISON 1978 1979 1980 1981

.. MPG PERCENT MPG PERCENT MPG PERCENT MPG PERCENT

Domestic vs.

EPA CAFE [3.0] [16.0] [2.B] [14.5] [3.2] [14.7] [3.4] [14.4]

Import Fleet vs.

EPA CAFE [4.1] [14.3] [2.2] [8.1] [3.0] [10.1] [4.7] [15.0]

Overall Fleet vs

EPA CAFE [3.3] [16.6] [3.0] [14.8] [3.4] [14.5] [3.8] [15.1]

Domestic vs.

Standard [2.3] [12.8] [2.5] [13.2] [1.4] [7.0] [1.8] [8.2]

Import vs.

Standard 6.6 36.7 6.0 31.6 6.7 33.5 4.7 21.4

Overall Fleet vs.

Standard [1.4] [7.8] [1.7] [8.9] 0.0 0 [0.6] [2.7]

NOTE: Bracketed entries represent negative values (i.e., on-road values

less than respective EPA CAFE or standard values).

On a relative overall fleet (e.g., both domestic and import

vehicles combined) basis, the on-road mpg is below the respective EPA CAFE

by about 15 percent or 3-4 mpg. These differences are quite close to the

differences noted for the domestic vehicles and, again, are to be expected

since domestic vehicles comprise the major portion of the U.S. passenger car

fleet.

19
2.1.3 ON-ROAD FUEL ECONOMY COMPARED TO THE FEDERAL STANDARDS

Table 2-3 also compares the on-road mpg with the Federal Standards

for the 4 model years, 1978-1981. As shown, the domestic fleet Is below the

Standard for each of the 4 years, by an average of 10.3 percent, or 2.0

miles per gallon. There is some indication that this difference may be

declining for the later model years (e.g., 1980-1961).

Imports, on the other hand, show an on-road mpg considerably above

the Federal standards, ranging from 21 to 37 percent (5-7 mpg) above the

standard levels. As pointed out earlier, however, the imports average

on-road mpg was originally (i.e., prior to enactment of the Federal

standards) at a level considerably above the level required by the

standards, as those vehicles have been, and remain, predominately small

cars.

On an overall fleet basis, the difference between on-road mpg and

the Federal standard levels appears to be narrowing, with the 1980-81

difference being about 1.5 percent compared to 8-9 percent in 1978-79. On

an mpg basis, this difference for 1980-81 averages less than one-half mile

per gallon, with the on-road average for 1980 exactly equaling the standard

level of 20.0 miles per gallon.

20
2.1.4 ON-ROAD FUEL ECONOMY BY VEHICLE SIZE CLASS

Table 2-4 displays the on-road fuel economy by vehicle size

class.6 From 1977 through 1981, consistent year-to-year gains were made for

most size classes. Over the full 4-year period, the average increase in mpg

per size class was 35 percent. The largest gain (79 percent) was registered

for the compact class, while the mini class had the lowest increase at 7

percent.

2.1.5 ON-ROAD FUEL ECONOMY BY MANUFACTURER

Tables 2-5 and 2-6 display the on-road fuel economy (MPG) by model

year for the domestic manufacturers and the import manufacturers,

respectively. The import table also includes "Ford" and "Chrysler" which

refer to the captive imports for these two manufacturers. These are broken

out since captive imports are to be treated separately (i.e., not combined

with vehicles manufacturer domestically) in accordance with the legislative

6 The size classes here essentially correspond to the EPA size classes as

defined In the annual "Gas Mileage Guide" publications for the respective

model years covered by the survey. One exception is the "mini" class which

includes not. only vehicles classified as "mini", but also vehicles

classified as "two-seaters."

21
TABLE 2-4

PASSENGER CAR ON-ROAD

FUEL ECONOMY

SIZE CLASS BY MODEL YEAR

Miles per Gallon for Model Years:

Size Class

Mini

Sub-Compact

Compact

Midsize

Large

Small Station

Wagon

Midsize Station

Wagon

Large Station

Wagon

1977

22.9

17.4

14.5

14.3

13.6

1976

21.0

21.2

16.4

15.2

14.5

1979

22.3

21.3

16.2

16.0

15.4

1980

23.4

23.3

19.1

1S.2

16.4

1981

24.5

24.3

25.9

19.6

17.6

19.2

13.9

21.0 21.5 24.0 25.4

15.7 16.2 17.2 19.7

13.0 14.3

14.0 15.8 16.5

NOTE: Sample sizes range from 19 to 491 vehicles for each of the 40 Size

Class-Model Year categories.

22
TABLE 2-5

PASSENGER CAR ON-ROAD FUEL ECONOMY BY MANUFACTURER (DOMESTIC)

AND-MODEL YEAR

MODEL

YEAR

1977

GEN.

14

MOTORS

.6

- Miles Per

FORD

13.9

Gallon -

CHRYSLER

U.O

AMC

15.4

1976 15.9 (19.0) 15.1 (18.4) 16.4 (18.4) 15.9 (18.6)

1979 16.4 (19.1) 16.1 (19.1) 17.4 (20.4) 17.B (19.9)

1980 18.7 (21.6) 16.8 (22.0) 17.9 (21.3) 18.0 (21.5)

1981 19.7 (23.2) 20.3 (23.3) 23.8 (26.4) 19.3 (22.5)

NOTE: Numbers in parentheses are the respective EPA CAFE levels.

Sample sizes range from 15 to 997 vehicles for each of the 20

manufacturer-model year categories.

23
TABLE 2-6

IMPORT PASSENGER CAR FLEET - ON-ROAO MPG

BY MANUFACTURER AND MOOEL YEAR

to

MODEL

YEAR

1977

1978

1979

1980

1981

DATSUN/NISSAN

23.4

22.6

26.8

26.9

25.7

(26

(26

(31

(30

• 8 )

.7)

.5)

.9)

HONDA

28.3

28.5

27.5

27.5

27.7

(33.7)

(29.8)

(30.0)

(31.0)

TOYOTA

21.4

22.4

21.6

24.1

25.5

(26.8)

(24

(27

(31

*)

.*)

0)

26.1

27.4

30.4

33.8

34.0

VW

(27.

(28.

(30.

(33.

2)

5)

8)

5)

30

22

25

19

FORD

.2 (37.3)

.5 (32.2)

.5 (29.9)

.6* (34.8)

CHRYSLER

24.

24.

22.

25.

29.

2*

2

..

4

3

(30.

(30.

(30.

(31.

6)

1)

7)

9)

NOTE: Numbers in parentheses are the respective EPA CAFE numbers.

•Sample size (i.e., number of vehicles in survey) less than 10;

remaining categories range in sample size from 10 to 215 vehicles.
stipulations for computing CAFE and determining compliance with Federal

Standards. Captive imports for years represented in the survey included:

Ford: Fiesta, Capri

Chrysler: Plymouth Arrow, Dodge Colt, Plymouth Champ,

Dodge Challenger, Plymouth Sapporo

2.1.5.1 DOMESTIC MANUFACTURERS

For the domestic companies (Table 2-5), the on-road mpg shows a

continuous improvement from Model Year 1977 through Model Year 1981. The

magnitude of these increases is reasonably consistent for all four manufacturers except for Chrysler in 1981 which showed a much larger than

average Jump of nearly six mpg. A major contributor to this large increase

for Chrysler was the introduction of the "K-cars" (i.e., Plymouth Reliant

and Dodge Aries), all new front-wheel drive cars which not only obtained

considerably higher mpg than models which they replaced (Volare and Aspen)

but also comprised a large portion of Chrysler sales for 1981.

Tables 2-7 and 2-8 summarize comparisons of the domestic

manufacturer on-road results with EPA CAFE's and Federal Standard levels,

respectively. Overall, on-road mpg remains below the EPA CAFE by a rather

consistent margin of 14-15 percent, or about three mpg and while no trends

are evident, Chrysler's 1981 mpg comes closest to the EPA CAFE level, being

below by less than 10 percent. The comparison against Federal Standard

levels yields similar results in that no trends are apparent. On-road mpg

25
TABLE 2-7

DOMESTIC PASSENGER CAR FLEET - COMPARISON

Of ON-ROAD MPG WITH EPA CAFE

BY

MANUFACTURER

MODEL

YEAR GENERAL MOTORS FORD CHRYSLER AMC

MPG PERCENT MPG PERCENT MPG PERCENT MPG PERCENT

1978 [3.1] [16.3] [3.3] [17.9] [2.0] [10.9] [2.7] [14.5]

1979 [2.7] [14.1] [3.0] [15.7] [3.0] [14.7] [2.1] [10.1]

1980 [3.1] [14.2] [3.2] [14.5] [3.4] [16.0] [3.5] [16.3]

.1961 [3.5] [15.1] [3.0] [12.9] [2.6] [9.8] [3.2] [14.2]

AVG. [3.1] [14.9] [3.1] [15.3] [2.8] [12.9] [2.9] [13.B]

NOTE: Brackets indicate negative values (i.e., on-road mpg less than EPA

CAFE).

26
TABLE 2-8

DOMESTIC PASSENGER CAR FLEET - COMPARISON

OF ON-ROAD MPG WITH FEDERAL STANDARD

BY

MANUFACTURER

MODEL

YEAR

1978

GENERAL MOTORS FORD CHRYSLER AMC

MPG PERCENT MPG PERCENT MPG PERCENT MPG PERCENT

[2.1] [11.7] [2.9] [16.1] [1.6] [8.9] [2.1] [11-7]

1979 [2.6] [13.7] [2.9] [15.3] [1.6] [8.A] [1.2] [6.3]

1980 [1.3] [6.5] [1.2] [6.0] [2.1] [10.5] [2.0] [10.0]

1981 [2.3] [10.5] [1.7] [7.7] 1.8 8.2 [2.7] [12.3]

AVG. [2.1] [10.6] [2.2] [11.3] [0.9] [4.5] [2.0] [10.1]

NOTE: Brackets indicate negative values (i.e., on-road mpg less than

Federal Standards).

27
lags the standard levels by about 10 percent or 2.0 mpg for General Motors,

Ford, and American Motors. Chrysler's overall decrease is less than 5

percent or approximately 1 mpg with the 1981 on-road figure being the only

instance where on-road mpg exceeds the Federal Standard.

2.1.5.2 FOREIGN MANUFACTURERS

The on-road mpg for the foreign manufacturers (or import vehicles)

was shown in Table 2-6. As stated earlier, the two domestic companies, Ford

and Chrysler, represent captive import categories, which for purposes of EPA

CAFE computation are classed as import vehicles. Volkswagen shows the

largest increase in on-road mpg among the six manufacturers. This is

attributed to the increasingly large penetration of diesel powered vehicles,

principally vw Rabbits, which occurred over the 1979-1981 period. Diesel

vehicles achieve substantially higher fuel economy than comparable vehicles

powered by gasoline engines (see Section 2.5). Among the other manufacturers, Oatsun/Nissan and Toyota show modest increases in on-road mpg for

the latest two-to-three model years. The other three manufacturers, Honda,

Ford, and Chrysler show no trends of mpg increases, with Honda's average

on-road mpg remaining essentially constant over the entire 5-year period. It

should also be noted in the case of these latter two manufacturers that the

sample sizes are rather small for some model years.

•Table 2-9 shows the import manufacturers on-road mpg versus EPA

CAFE comparison. Overall, no trends are evident. For all except one

manufacturer, VW, on-road mpg shows an essentially consistent decrease

28
TABLE 2-9

IMPORT PASSENGER CAR FLEET - COMPARISON OF

ON-ROAD MPG WITH EPA CAFE BY MANUFACTURER

MODEL

YEAR OATSUN/NISSAN HONDA TOYOTA VW FORD CHRYSLER

PERCENT MPG PERCENT MPG PERCENT MPG PERCENT MPG PERCENT MPG PERCENT

1978 I[4.2] [15.7] |[5.2] [15.4] | [4.4] [16.4] | 0.2

I I I 1

1979 I 0.1 0.4 |[2.3] [7.7] | [2.8] [11.5]

I I I

1980 |[4.6] [14.6] I£2.5] [8.3] | [2.7] [9.9]

I I I

1981 |[5.2] [16.8] |[3.3] [10.6]| [5.5] [21.6]

I I

1.9

3.0

0.5

0.7

6.7

9.7

[7.3] [19.6]

[9.7] [30.1]

[4.5] [15.1]

1.5 l[15.2] [43.7]

[6.A] [20.9]

[7.7f [25.5]

[5.3] ,[17.3]

[2.6] [8.2]

I I I

AVG |[4.0] [11.7] |[3.3] [10.5]| [3.9] [14.9]

I

1.4 4.7 | [9.2] [27.1] [5.5] [18.0]

NOTE: Brackets indicat e negative values (i.e. , on-road mpg less than EPA CAFE),

7

 Sanple size less than 10

29
relative to EPA CAFE, with Ford showing the greatest disparity (again, small

sample sizes in some cases mean Individual model year estimates are subject

to greater variability). Volkswagen's on-road mpg in all instances is

slightly above the EPA CAFE level; this is believed primarily due to its

high proportion of diesel powered vehicles.

The comparison of import on-road mpg with the Federal standards is

displayed in Table 2-10. As would be expected from the results discussed

above, on-road mpg exceeds the Federally required level in nearly every

instance. The degree to which the on-road mpg exceeds the Federal levels is

typically quite large, ranging from a low of approximately 19 percent (for

Toyota) to a high of nearly 60 percent (for VW).

2.2 LIGHT TRUCKS - TWO WHEEL DRIVE: ON-ROAD FUEL ECONOMY

On-road fuel economy for light trucks is shown in Table 2-11 for

both domestic and import manufacturers, along with the respective EPA CAFE

for each Model Year 1978-1981. The data are divided by two-wheel and

four-wheel drive configurations corresponding to the manner in which the

Federal Regulations were set for this class of vehicles. Figure 2-2

displays graphically the data in Table 2-11 , showing the trend by model

year.

It should be noted that fuel economy regulations for light trucks

began in 1979, 1 year later than for passenger cars. Therefore, the base

year for estimating fuel economy improvement for light trucks is Model Year

1978.

30
TABLE 2-10

IMPORT PASSENGER CAR FLEET - COMPARISON OF

ON-ROAD MPG WITH FEDERAL STANDARD LEVELS

MODEL

YEAR

1978

1979

1980

1981

AVG

DATSUN /NISSAN

MPG

4.6

7.8

6.9

3.7

5.8

PERCENT

25.5

41.1

34.5

16.8

29.5

HONDA

MPG

10.5

8.5

7.5

5.7

10.6

PERCENT

58.3

44.7

37.5

25.9

41.6

TOYOTA

MPG

4.4

2.6

4.1

3.5

3.7

PERCENT| MPG

24.4

13.7

20.5

15.9

18.6

I 9.4

i

1

1 11.4

i

1

1 13.8

i

1

1 12.0

I

I

I 11.7

VW

PERCENT

52.2

60.0

69.0

54.5

58.9

FORD

MPG PERCENT

12.2

3.5

5.5

[2.4«]

5.9

67.6

18.4

27.5

[10.9]

28.1

CHRYSLER

MPG

6.2

3.4«

5.4

7.3

5.6

PERCENT

34.4

17.9

27.0

33.2

28.1

NOTE: Brackets Indicate negative values

* Sanple size less than 10

31
TABLE 2-11

LIGHT TRUCK ON-ROAD FUEL ECONOMY, AND

COMPARISONS TO EPA CAFE

- DOMESTIC AND IMPORT FLEETS -

Miles Per Gallon

FLEET

Domestic

On-Road

EPA CAFE

Import

On-Road

EPA CAFE

Overall On-Road

Overall EPA CAFE

1978

12.38

(N/A)-

22.39

(N/A)

13.41°

(N/A)

Two-Wheel

1979

15.2

17.9

20.5

20.9

15.7

18.4

Drive

1980

14

17

21

25

16

19

7

5

.3

0

.4

3

1981

14.9

18.6

24.3

28.0

16.9

20.7

1978

12.3

(N/A)

--

(N/A)

12.31

(N/A)

Four-Wheel Drive

1979

12.9

16.5

_-

25.6

1 12.9

16.6

1980

12

15

18

21

13.

16

.9

.2

.5

.8

6

.1

1981

13.4

17.1

19.3

24.3

14.4

18.6

Fuel Economy

Standard (N/A) 17.2 16.0

I

16.7 | (N/A) 15.8 14.0 15.0

NOTE 1: For Model Year 1979, the light truck fuel economy standards applied

only to those light trucks having a gross vehicle weight rating (GVWR) of

6,000 pounds or less. In Model Year 1980, the standards were broadened to

apply to al l light trucks having a GVWR of 8,500 pounds or less.

NOTE 2: For 1979, domestic manufacturers were permitted to include captive

import trucks in their overall EPA CAFE figures, whereas beginning with

Model Year 1980, captive imports had to be separated as a special class.

NOTE 3: Sample sizes for each of the 16 base categories range from 27 to

244 vehicles.

NOTE 4: While the above EPA CAFE'S are correct as of this writing,

rulemaking action in process may adjust upward the above CAFE'S for Model

Year 1980 and later (see Note 2, Table 2-1).

8

 Includes vehicles with GVWR £ 8,500 lbs.; excluding vehicles >_ 6,000

lbs., but less than 8,500 lbs., GVWR, and including captive imports,

the figure is 14.1 mpg..

9

 Includes captive imports.

1 0

 Excluding vehicles > 6,000 lbs., figure is 15.2 mpg.

1 1

 Excluding vehicles > 6,000 lbs., figure is 13.7 mpg.

32

Standards for trucks began a year later (Model Year 1979 instead of

Model Year 1976) than for passenger cars, and the year-to-year progression

in standard levels was less than for passenger cars. It should be noted

that beginning with 1980, the light trucks regulations included vehicles up

to 8,500 lbs. Gross Vehicle Weight Rating (GVwR), whereas the 1979 standard

only included vehicles up to 6,000 lbs. GVWR. Also for 1979, the domestic

manufacturers were permitted to include captive import trucks in the overall

EPA CAFE computation, whereas in 1980 and later captive import trucks had to

be excluded as a separate segment for the domestic companies.

2.2.1 ON-ROAD FUEL ECONOMY COMPARED TO EPA CAFE

Comparing on-road fuel economy for two-wheel drive light trucks

with CAFE levels (as computed from EPA laboratory tests), the following

observations are made (see Table 2-12):

(1) The on-road mpg for the overall fleet is below the

EPA CAFE mpg by an average of 16 percent per each year,

1979 through 1981. On a miles per gallon basis, this

difference increases from 2.7 in 1979 to 3.8 in 1981.

(2) For domestic vehicles, there is a slight trend that the

difference between on-road mpg 8nd the EPA CAFE may be

increasing, on both a relative, or percent, and an absolute,

or mpg basis.

34
TABLE 2-12

LIGHT TRUCK: TWO-WHEEL DRIVE -

COMPARISON OF ON-ROAD FUEL ECONOMY

WITH

EPA CAFE AND WITH FUEL ECONOMY STANDARDS

COMPARISON 1979

-MODEL YEAR1980

MPG PERCENT MPG PERCENT

Domestic with

EPA CAFE [2.8] [15.6] [2.8] [16.0]

Import with

EPA CAFE [0.4 ] [1.9 ] [3.7 ] [U.8]

Overall Fleet

With EPA CAFE [2.7] [14.7] [2.9] [15.0]

1981

MPG PERCENT

[3.7] [19.9]

[3.7] [13.2]

[3.8] [18.4]

Domestic with

Standard [2.1] [13.2]

Import with

Standard 3.3 19.2"

Overall Fleet

with Standard [1.5] [8.7]

[1.3] [8.1] [1.8] [10.8]

5.3

0.4

33.1

2.5

7.6 45.5

0.2 1.2

NOTE: Brackets indicate negative values, i.e., on-road values less than

standard values.

35
(3) Tor import trucks, the on-road fuel economy remains below

the EPA CAFE values for 1980 and 1981 by approximately

14 percent or 3.7 mile per gallon. This contrasts with

1979 which saw import trucks on-road mpg only slightly

less (1.9 percent) than the EPA CAFE.

(4) Overall, the EPA CAFE figures for light trucks exceed

on-road experience by amounts similar to those noted for

passenger cars—approximately 16 percent per year, or

from 3 to 4 miles per gallon.

2.2.2 ON-ROAD FUEL ECONOMY COMPARED TO FEDERAL STANDARD

Comparing on-road experience of two-wheel drive light trucks with

the Federal Standard levels yields the following observations:

(1) On an overall (fleet) basis, the on-road results are quite

close to the standard levels. In fact for the latest 2

years, I960 and 1981, the on-road mpg actually exceeds the

standards slightly (by 1 to 2 percent).

(2) The primary reason for this close correspondence between

overall fleet mpg and the Federal Standards is the wide

margin by which the import trucks exceed the respective

standards. For the 3 model years 1979 to 1981, import trucks

increasingly exceed the standards, ranging from 19.2 percent

36
in 1979, to 45.5 percent In 1981. Conversely, the on-road

mpg of domestic trucks is below the standards for each of the

3 model years by an average of 10.7 percent. Again, however,

as was the case for passenger cars, import trucks had a much

higher on-road mpg prior to enactment of the Federal

Standards than did domestic trucks. The original (Model Year

1978) mpg for the imports was even higher than the ultimate

standard level for 1981. Therefore the impetus for fuel

economy improvement was much greater for the manufacturers of

domestic trucks than for the manufacturers of import trucks

and, as was the case for passenger cars, the relative

increase in on-road mpg-was.-greater- for domestic trucks than

for import trucks.

2.3 LIGHT TRUCKS - FOUR-WHEEL DRIVE: ON-ROAD FUEL ECONOMY

Survey data for four-wheel drive trucks were not as complete as

for two-wheel drive vehicles. The survey results for these vehicles along

with respective EPA CAFE's and Federal Standards are shown in Table 2-13.

For domestic trucks with respect to EPA CAFE, it .is seen that the

on-road experience again falls below EPA CAFE levels by an amount ranging

from 15 to 22 percent. Compared to the Fuel Economy Standards, the on-road

decrease is not as large, ranging from 18 percent in 1979 to 11 percent In

1961.

37
TABLE 2-13

LIGHT TRUCK: FOUR-WHEEL DRIVE -

COMPARISON OF ON-ROAD FUEL ECONOMY

WITH

EPA CAFE AND WITH FEDERAL STANDAROS

- MODEL YEAR -

COMPARISON 1979 1980 1981

MPG PERCENT MPG PERCENT MPG PERCENT

Domestic with

EPA CAFE [3.6] [21.8] [2.3] [15.1] [3.7] [21.6]

Import with

EPA CAFE -- — [3.3] [15.1] [5.0] [20.6]

Overall Fleet

with EPA CAFE — — [2.5] [15.5] [4.2] [22.6]

Domestic with

Standard [2.9] [18.4] [1.1] [7.9] [1.6] [10.7]

Import with

Standard — — 4.5 32.1 4.3 28.7

Overall Fleet

with Standard — — [0.4] [2.9] [0.6] [4.0]

NOTE: Brackets indicate negative values (i.e., on-road values less than the

Standard.

38
For the 2 years for which comparisons may be made for import

trucks, Table 2-13 shows that on-road mpg Is lower than EPA CAFE levels by

15-21 percent, differences similar to those noted for the domestic two-wheel

drive trucks, with respect to the Fuel Economy Standards, as was the case

for passenger cars, there is a marked difference in the opposite

direction—on^road mpg exceeds the Federal Standards by a considerable

margin. For 1980, on-road mpg exceeds the Federal Standard of 14.0 mpg by

32 percent; for 1981, on-road mpg is 29 percent higher.

For the overall fleet of four-wheel drive trucks, the 1980 and

1981 on-road fuel economy is lower than the EPA CAFE by 15 to 23 percent.

Relative to the Federal Standards, the on-road mpg is quite close, trailing

by only 3 to A percent. Once again, this close agreement is primarily due

to the import trucks which, although representing a minor portion of the

total truck fleet, exhibit a much higher on-road fuel economy level.

Figure 2-3 is a graphic display of the data for four-wheel drive

trucks, taken from Table 2-11.

2.4 LIGHT TRUCK ON-ROAD FUEL ECONOMY BY SIZE CLASS

Table 2-14 summarizes the light truck on-road results by vehicle

size class. It shows that the gains made by light trucks over the 3-year

period of the standards were generally small, compared to the gains made in

the passenger car sector. In a few instances, certain size classes show an

on-road reversal (e.g., decrease in mpg), rather than an increase.

39

TABLE 2-14

LIGHT TRUCK ON-ROAD

FUEL ECONOMY -

SI2E CLASS BY MODEL YEAR

SIZE

CLASS

2WD

Small Pickup

Standard Pickup

Vans

Special Purpose

4WD

Small Pickup

Standard Pickup

Special Purpose

1978

22.8

11.9

13.3

13.0

—

—

12.3

MODEL

1979

20.8

13.0

13.1

13.9

—

—

11.5

YEAR

1980

21.5

15.7

13.4

10.1

18.5

12.1

14.0

1981

24.6

15.4

13.7

12.9*

19.4

13.9

14.1

•Sample size less than 10 vehicles.

Sample sizes for remaining cagetories vary from 18 to 170 vehicles,

41
2.5 DIESELIZATION

One of the primary technological developments made in the drive

for better fuel economy was the diesel engine. For the Model Year period

covered in the survey, the two manufacturers with significant numbers of

diesel powered vehicles were Volkswagen (VW) and General Motors (GM).

During the 1980-1981 period, diesel Rabbits comprised a major share of that

carline for vw and diesel engines were also offered in VW's small pickup

truck. Although GM's diesel penetration never grew to a significant

proportion of its total yearly sales, it nevertheless sold considerable

numbers of diesel vehicles. These diesel vehicles were confined to certain

makes of GM's midsize and large (or standard) size carlines with a high

concentration in the Oldsmobile Division (Cutlass Supreme, Cutlass Cruiser,

Delta 88, 98, and Custom Cruiser). GM also offered the diesel option in its

standard size pickup trucks (Chevrolet and GM). Since diesel vehicles were

a very small proportion of the total number of fleet vehicles registered for

each year, they were oversampled in order to assure that reasonable numbers

appeared in the final survey sample.

2.5.1 EFFECT OF DIESELIZATION ON FUEL ECONOMY

While it is generally well known that diesel vehicles obtain

better fuel economy than comparable vehicles with gasoline engines, the

survey provides a basis for estimating the extent of the diesel's fuel

economy advantage in typical, everyday driving throughout the Nation. Table

2-15 summarizes the results of this comparison for the 6 vehicle classes

discussed above. The data indicate a substantial fuel economy advantage for

42
TABLE 2-15

COMPARISON OF FUEL ECONOMY (MPG) BETWEEN DIESEL AND

GASOLINE POWERED VEHICLES

Vehicle Class/

Fuel Type 1978

— MODEL YEAR —

1979 1980 1961

Subcompact (VW Rabbit)

Gasoline

Diesel

Diesel Pet. Increase,

25.

44.

75.

60

99

756

28.

41.

46.

56

94

8X

26.

42.

60.

39

35

5X

27

42

52

.64

.07

.2X

Midsize Sdn (GM)

Gasoline

Diesel

Diesel Pet. Increase

N/A

16.

23.

44.

26

45

2*

16.

22.

35.

33

11

4X

17

23

37

.42

.96

.5X

Midsize St. Wgn. (GM)

Gasoline

Diesel

Diesel Pet. Increase

N/A

16.

22.

30.

89

09

6X

15.

21.

38.

45

44

8X

17

24

38

.65

.39

.2%

Large Sdn (GM)

Gasoline

Diesel

Diesel Pet. Increase

14

21

47

.34

.18

.7X

15.

21.

39.

58

71

3X

15

21

37

.92

.81

.OX

16.

23.

40.

74

49

3X

A3
TABLE 2-15 (Continued)

Vehicle Class/

Fuel Type

Large St. Wgn. (GM)

Gasoline

Diesel

Diesel Pet. Increase

— MODEL YEAR —

1978

14.61

20.45

40.0%

1979 1980

14.51 14.35

20.18 21.11

39.1% 32.OX

1981

15.42

20.86

35.3%

Small Pickup (Vw)

Gasoline

""01 e se 1

Diesel Pet. Increase

N/A

26.

N/A 37.

39.

76

23

1%

28.

38.

33.

72

34

5%

Standard Pickup (GM)

Gasoline 12.74

Diesel 17.54

Diesel Pet. Incr-ease 37.7X

14.25 14.79

19.33 18.30

35.6% 23.7%

16.69

18.28

9.5X

44
the diesel engine over a generically similar vehicle equipped with a

gasoline engine. While little difference is noted among model years within

vehicle classes or between sedans.and station wagons within the same size

class, the extent of the advantage for diesel vehicles does appear to be

related to vehicle size/weight and also to vehicle type (car or truck). The

average increase, per model year, in fuel economy for diesels is highest at

almost 59 percent for the subcompact class (VW) compared to an average

advantage of 38 percent for the combined midsize/large class, both sedans

and station wagons (GM). for trucks the same trend holds, but with a smaller

advantage for the diesel and a smaller advantage than for passenger cars.

The average increase for diesels in small trucks (VW) is 36 percent compared

to about 27 percent for standard size pickups (GM). Two probable reasons

for the lower diesel advantage in trucks versus cars are the higher

gearing/axle ratios for trucks and the heavier usage environment experienced

by trucks (e.g., heavier loads, less highway driving, etc.).

2.5.2 DIESEL ON-ROAD FUEL ECONOMY VERSUS EPA LABORATORY ESTIMATES

In addition to the fuel economy advantage over gasoline engines, a

second topic of interest relative to the diesel engine is whether diesels

exhibit the same relationship between on-road fuel economy and laboratory

(or EPA) fuel economy as do gasoline engines. In Section 2.1.2 of this
chapter it was found that for all model years studied, and for all passenger

cars, the on-road fuel economy was approximately IS percent less than the

laboratory tests (or EPA CAFE) for generically similar vehicles.

In order to evaluate the laboratory to on-road relationship for

diesel engines, the on-road results for the sample of diesel powered

passenger cars for the 1981 model year was compared with the respective EPA

figure, or rating. The 1981 models represent the most recent model year

available in the survey and a total of 286 vehicles were available

representing the two major manufacturers of diesel power passenger cars for

that period, General Motors and Volkswagen. General Motors vehicles in the

sample were comprised of midsize passenger cars and midsize station wagons;

and standard or large size passenger cars and large station wagons. All GM

cars were powered by the eight-cylinder, 350 cubic inch diesel engine

manufactured by Oldsmobile. The Rabbit represented Volkswagen's diesel car

in the sample and all had the standard four cylinder engine displacing 97

cubic Inches.

Table 2-16 contains the data for the nine make models in the

sample. The EPA MPG figures are the EPA "combined" numbers which are

harmonically weighted averages of "city" and "highway" numbers in the ratio

of 55 percent city and 45 percent highway. The "percent decrease" column is

the amount by which the on-road MPG falls below the EPA combined MPG.

46
TABLE 2-16

DIESEL ON-ROAO FUEL ECONOMY VERSUS EPA LABORATORY

ESTIMATES; 1981 PASSENGER CARS

Vehicle

Make/Model

vw Rabbit

Oldsmobile

Cutlass Supreme

Oldsmobile 88

Pontiac Bonneville

Oldsmobile 98

Oldsmobile Cutlass

Oldsmobile Cutlass

Cruiser

Oldsmobile Custom

Cruiser

Chevrolet Caprice

Wagon

No.

in

Vehicles

Samples

On-Road

MPG (Avq.)

EPA

MPG

Avg. Percent

Decrease - EPA

to On-Road

74

34

46

21

15

21

21

27

27

42.07

24.66

23.92

23.94

23.13

24.64

24.39

21.79

20.69

46

27

26

26

26

27

27

23

23

8.6

8.7

8.0

8.0

11.0

8.7

8.7

5.5

9.2

Average pet. decrease, EPA - to on-road (weighted) = 8.4

47
As the table shows, on-road mpg is consistently lower than

laboratory tested mpg with the overall weighted average showing on-road mpg

for diesel cars being 8.A percent lower. This is only slightly more than

one-half the decrease of approximately 15 percent noted earlier for the

entire fleet of cars, the large majority of which are gasoline powered.

Thus it appears that laboratory results more accurately reflect the fuel

economy achieved by owners of diesel cars than it does the fuel economy

achieved by owners of typical gasoline powered cars.

2.6 SEASONAL EFFECT ON FUEL ECONOMY

Several factors influence the fuel economy of a vehicle in the

real world driving environment. In addition to the characteristics peculiar

to the vehicle itself (size/weight of vehicle, engine size, type of

transmission, type of fuel, axle ratio, aerodynamics, air- conditioning,

etc.), other factors pertaining to the driver, the way in which the vehicle

is used (load/cargo carried, highway versus "off-road" usage, etc.), and the

environment in which the vehicle operates, all can have an impact on on-road

fuel economy.

Under the area of environment, one of the primary factors

affecting fuel economy is the "seasonal" effect. This seasonal effect might

also be referred to as the "winter-summer" effect, and is, in turn, composed

of two principal subfactors, the ambient temperature of the environment In

which the vehicle operates, and the way in which the vehicle is used. Under

cold temperature conditions, as opposed to warm/hot temperatures, the engine
must operate on a richer fuel-air mixture (e.g., choke engaged) until the

engine reaches a certain operating temperature. Additionally, "winter"

driving typically involves more short trip driving than "summer" driving.due

to most vacation/recreation travel being in the warmer seasons of the year.

Short trip driving typically results in poorer fuel economy since engine

temperatures often fall to reach maximum operating levels where best fuel

economy is obtained.

Since the On-Road Survey was conducted throughout an entire

12-month period, it provides a method of estimating the seasonal effect on

fuel economy. Table 2-17 summarizes the fuel economy results by the four

seasons in which the data were collected. The winter period is defined as

January 1983 through March 1983, the summer period as April 1983 through

June 1983, etc. The data have been combined for all vehicles in the survey,

including passenger cars as well as light trucks, in order to obtain more

stable statistical estimates of the seasonal effect. The data, as well as

the plot in Figure 2-4, show a very consistent seasonal effect, for both the

individual model years represented in the survey and for the overall results

of the five model years. If we define "winter" as January through March

plus October through December, and "summer" as April through September, the

overall seasonal effect on fuel economy is estimated to be 18.90 -17.83 •

1.07 mile per gallon, or approximately one mile per gallon. This result is

similar to that found in other studies.1^

12 "Passenger Car Fuel Economy: EPA and Road," J. D. Murrell, EPA460/3-80-010,

January 1980.

"In-Use Fuel Economy of 1980 Passenger Cars." R. W. Schneider, B. W. Lipka,

and F. K. Miller, General Motors Corporation, SAE Paper #810384,

February 23-27, 1981, meeting in Detroit, Michigan.
TABLE 2-17

ON-ROAD FUEL ECONOMY BY SEASON OF YEAR

(PASSENGER CARS PLUS LIGHT TRUCKS)

MODEL

YEAR

1977

1978

1979

1980

1981

OVERALL

WINTER

n

250

362

424

493

635

2164

(Jan.-Mar.)

"x

15.19

16.46

17.34

19.97

21.46

17.93

SPRING

n

291

419

468

507

721

2406

(Apr.-June)

"x

16.33

17.95

18.27

20.96

22.53

18.95

SUJtCR

n

267

333

405

461

636

2102

(July-Sept)

X

15.91

17.31

18.55

21.27

22.34

18.84

FALL

n

253

331

396

475

602

2057

(Oct.-Oec.)

X

14.66

16.27

17.25

20.10

21.40

17.72

WINTER/FALL: n = 4221, X = 17.83

SPRING/SUMMER n = 4506, X = 18.90

n • no. vehicles in sample

X s mean fuel economy

NOTE: estimates are weighted arithmetic means

50

2.7 COMPARISON OF ORFES RESULTS WITH PRIOR STUDIES OF ON-ROAO FUEL

ECONOMY

As has been stated earlier in this report, several prior studies

of on-road fuel economy have been made together with comparisons and

analyses of on-road results with laboratory fuel economy measurements as

developed by the Environmental Protection Agency. This section compares the

results of these earlier studies with the results obtained in the ORFES.

Four primary studies have been selected representing efforts by the

Department of Energy, the Environmental Protection Agency, General Motors,

and Ford Motor Company.

2.7.1 DEPARTMENT OF ENERGY STUDIES

Some of the earliest studies of on-road fuel economy were made by

the Department of Energy (DOE). Studies13 by McNutt et. al., were among the

first to document the existence of a decrease between laboratory (EPA) fuel

economy and on-road fuel economy. These earlier studies were based on

passenger car Model Years through 1978 and used on-road data primarily from

fleet operated, domestically produced (i.e., data on import vehicles was

essentially absent) vehicles. In addition to the lower on-road finding,

these DOE studies also concluded that the magnitude of this difference was

increasing with later Model Year vehicles and with higher-mpg vehicles. The

"A Comparison of Fuel Economy Results from EPA Tests and Actual In-gse

Experience, 1974-1977 Model Year Cars", by Barry D.Mc Nutt, Diane Pirkey,

U.S. Dept. of Energy and Robert Dulla, Craig Miller, Energy and Environmental Analysis, Inc., February 1978.

"On-Road Fuel Economy Trends and Impacts" by Barry D. McNutt, U.S. Dept. of

Energy and Robert Dulla, Energy and Environmental Analysis, Inc., February

1979.

"Statement of Barry D. McNutt, Senior Technical Advisor, Office of

Conservation Policy and Evaluation, U.S. Dept. of Energy before the

Sub-committee on Environment, Energy, and Natural Resources of the Committee

on Government Operations", January 29,1980.

52
EPA to on-roatj decrease was estimated at 21 percent for Model Year 1978. In

contrast to these findings, the ORFES data show a decrease in the EPA to

on-road difference from Model Year 1977 to Model Year 1978 (18.3 percent to

16.6 percent). Additionally, ORFES estimates of on-road fuel economy are

consistently higher than those found in the DOE studies. It is believed

that the difference between the ORFES and DOE findings could largely be due

to the representativeness of the data bases used. Use of primarily fleet

data by DOE together with the absence of data on import cars could well

produce lower fuel economy estimates than ORFES, which was a national

probability sample of the entire population of privately owned vehicles,

Including both domestic and import vehicle. It is also arguable that fleet

vehicles, by nature of the environment in which they are operated and

maintained, could achieve lower fuel economy than privately bwneoT vehicles.

A later study1* by DOE covering vehicles through Model Year 1981 and

incorporating additional data on private vehicles(from "postcard" surveys by

General Motors and Ford) showed a reversal in the earlier, trend of

increasing gap—the 1979-1980 Models showed less difference between EPA and

on-road than 1978 and earlier years. This reversal was attributed to

changes in 1979 test procedures by the EPA and to new vehicle technologies

(i.e., diesels, front-wheel drive, fuel injection, and manual transmissions)

which were concluded to show a lower EPA to on-road gap than conventional

technology vehicles (gasoline engine, rear wheel drive, carburetted,

u "Comparison of EPA and On-Road Fuel Economy for 1975-1980 Cars," by B.

McNutt, Dept. of Energy; R. Dulla and R. Crawford, Energy and Environmental

Analysis, Inc., and H.T. McAdams, Falcon Research and Development Co.,

February 1981 (Copies of slides from Society of Automotive Engineers

presentation).

53
automatic transmission). The ORFES results showed a similar drop in the EPA

to on-road mpg for 1979-1980 vehicles (14.5 to 14.8 percent) over 1977-1978

vehicles (16.6 to 18.3 percent).

Still a third DOE study15 compared on-road fuel economy and EPA

measured fuel economy for the (then) relatively new diesel power passenger

cars. This study concluded that: (1) diesel vehicles average 45 percent

better on-road fuel economy than comparable gasoline vehicles, and (2)

diesel vehicles exhibit significantly less EPA-to-on-road difference than do

gasoline vehicles, from 5 percent to 11 percent, at 20 (EPA) mpg and 40

(EPA) mpg, respectively. The ORFES results (Section 2.5.1 and 2.5.2)

showed: (1) diesel on-road advantage was 38 percent to 59 percent,

depending on car/engine size, and (2) diesel decrease, EPA to on-road, of

only 8.4 percent or only slightly more than one-half the decrease noted for

the fleet as a whole. Thus the ORFES and DOE findings regarding diesel

vehicles are generally similar.

2.7.2 ENVIRONMENTAL PROTECTION AGENCY STUDY

As a consequence of the emerging concern over differences in EPA

fuel economy and consumer-achieved fuel economy, the Congress authorized the

EPA to conduct a special study to evaluate this issue and to prepare a

detailed report on the degree to which laboratory fuel economy data provide

realistic estimates of the fuel economy likely to be achieved by the driving

15 "Comparison of Gasoline and Diesel Automobile Fuel Economy as Seen by the

Consumer," by Bairy 0. McNutt, U.S. Dept of Energy, paper for SAE Annual

Meeting, December 1980 (meeting February 1981).

54
public. The EPA study16 often referred to as the "404 Study," responding to

this statutory action produced on-road fuel economy estimates which were

lower and EPA to on-road estimates which were higher than those found in

ORFES. For the years 1977 through 1979, the 404 study estimated on-road fuel

economy to range from 14.7 mpg to 16.9 mpg compared to 15.2 mpg to 17.3 mpg

for ORFES. Estimates of EPA to on-road decrease ranged from 19.7 percent to

15.9 for the same years, compared to a range of 18.3 percent to 14.8 percent

for ORFES. Much of the data used in the 404 study was the same data used in

the DOE studies, discussed above, and hence the reasons for the divergence

from the ORFES data are believed to be the same as previously cited, namely,

the predominance of fleet data and lack of data on import vehicles for the

404 Study, thereby likely biasing the data insofar as national

representativeness was concerned. The EPA did acknowledge in the 404 Report

these two shortcomings of the data which could hinder representativeness tnd

therefore Introduce a potential bias into the subsequent analysis and

conclusions reached in the study.

2.7.3 GENERAL MOTORS STUDY

Schneider17 et.al., in 1980-1981 conducted an on-road survey

utilizing a methodology which closely paralleled the methodology used in

NHTSA's ORFES. The survey was confined to 1980 passenger cars, but used a

stratified random sample from the R.L. Polk registration files, the same

frame used for ORFES. Sample allocation in the GM survey was on a quota

16 "Passenger Car Fuel Economy. EPA and Road, A Report to the Congress," In

Response to the National Energy Conservation Policy Act of 1978, Public Law

95-619, Title IV, Part 1, Section 404, Environmental Protection Agency,

September 1980.

17 "In-Use Fuel Economy of 1980 Passenger Cars", R.W. Schneider, B.w. Lipka,

and F.K. Miller, General Motors Corporation, SAE Paper #810384, February

23-27, 1981 meeting In Detroit, Michigan.

55
basis relative to each car line (make-model), whereas ORFES used basically a

proportional allocation within model years. Both surveys sampled domestic

as well as import cars. The GM survey did not cover light trucks. The data

collection instrument was also similar to that used in ORFES, consisting of

a diary record of fuel purchases and odometer readings. One principal area

where the GM survey differed from ORFES was the collection period. The GM

data represented only 6 months, August 1980 through January 1981, with over

90 percent of the returns representing only a 3-month driving period,October

1980 through Oecember 1980. ORFES, as previously stated, was conducted

tnroughout an entire 12-month period, January through December of 1983. The

response rate was much lower in the GM survey with the diaries constituting

the final data base representing only 9.2 percent of the total number

(52,770) of diaries originally mailed.

The GM survey found the average on-road fuel economy for the 1980

Model Year passenger fleet to be 19.9 mpg, which is surprisingly close to

the ORFES estimate of 20.0 mpg. However, closer inspection reveals that

the true GM estimate is probably higher than the ORFES estimate. Since the

GM survey was heavily concentrated in 3-month period (over 90 percent in

October - Oecember 1980), the seasonal effect on fuel economy was not

accounted for. The ORFES survey (Section 2.6 of this chapter) indicates

that for the October-December period, overall average fuel economy is lower

by approximately one mile per gallon than for the "summer" months (April -

September). Therefore, approximately 0.5 mpg would have to be added to the

GM, October - December estimates in order to compensate for the seasonal

effect on fuel economy. This gives 19.9 • 0.5 x 24.A18 mpg as the seasonally

18 Tnls adjustment assumes that there was no significant difference between the

seasonal effect of comparable periods of 1980, when the GM survey was

conducted, and 1983, when ORFES was conducted.

56
adjusted GM estimate which is still reasonably close to the ORFES estimate

of 20.0 mpg. It should be noted that Schneider et al did recognize this

seasonal bias in their data and discussed adjustment factors which were of

the same general magnitude as those discussed above, drawn from the NHTSA

survey.

2.7.4 FORD MOTOR COMPANY STUDY

The fourth and final study to be compared with the ORFES study was

one done by South19 of Ford Motor Company. This study utilized data from

only Ford vehicles operated under lease fleet conditions by Ford employees.

Passenger car data for 1978 through 1980 models were presented together with

limited results for 1980 light trucks.

The Ford study estimated the (Ford) on-road fuel economy for

passenger cars at 14.7 mpg, 16.6 mpg, and 18.7 mpg, for Model Years 1978,

1979 and 1980 respectively. These corresponded to EPA to on-road decreases

of 20X, 13X, and 15%, respectively. Corresponding ORFES results for Ford

cars (Table 2-5) were I5.1mpg, 16.1 mpg, and 18.8 mpg. These are higher

than the South estimates except for 1979, which is lower. For EPA to

on-road decrease, ORFES estimates are 17.9%, 15.7X, and 14.5X. ORFES data

show lower EPA to on-road difference for 1978 and 1980, and greater EPA

on-road difference for 1979.

19 ni97e to 1980 Ford On-Road Fuel Economy," Neil South, draft of SAE Paper No.

810383 for presentation at 1981 SAE International Congress and Exposition on

February 26,1981.

57
For 1980 light trucks, the limited data of the Ford study

estimated on-road fuel economy at 13.9 mpg and 11.6 mpg for two-wheel and

four-wheel drive trucks respectively. These corresponded to EPA to on-ro«d

differences of 20X for each type (i.e., drive) of truck. Due to smaller

sample sizes for light trucks relative to passenger cars, this report does

not break out estimates by manufacturer for light trucks. However, for 1980

domestically-produced light trucks, ORFES estimates for on-road fuel economy

are:

Two-wheel drive: 14.7 mpg

Four-wheel drive 12.9 mpg

Corresponding ORFES estimates for EPA to on-road differences are:

Two-wheel drive: 16%

Four-wheel drive: 15.IX

For trucks, ORFES on-road estimates are higher than the Ford Fleet

estimates and therefore the decreases,.EPA to on-road, for ORFES are-lower

than the Ford fleet estimates.

Summarily, ORFES estimates, for both cars and trucks, generally

show higher on-road fuel economy and lower EPA to on-road difference than

the Ford study. As with the earlier studies discussed in this Section, the

reason for these differences is believed likely due to the difference in

representativeness of the data sources employed. It should be noted,

58
however, that the Ford study did find that the amount of EPA to on-road

difference remained essentially constant over the model years estimated—a

finding which is in agreement with the ORFES study.

2.7.5 SUMMARY OF ORFES COMPARISON WITH OTHER ON-ROAD FUEL ECONOMY

STUDIES

It is concluded, from the above comparison of ORFES with other

in-use fuel economy studies that the representativeness of the data is the

primary factor affecting the on-road fuel economy estimates. Use of

primarily fleet data and data which excludes smaller (import) vehicles

generally produces lower on-road estimates, and correspondingly, greater

laboratory to on-road differences than data representing the general

population of American drivers of all vehicles, of all size classes and of

both domestic and import manufacture. The General Motors study, which used

a sampling methodology most closely approximating that used in ORFES gave

on-road estimates closest to those results obtained in ORFES. Aside from

these issues, however, several of the other findings and trends were

reasonably similar between the prior studies and ORFES.

2.8 ESTIMATED REDUCTION IN FUEL CONSUMPTION AND EQUIVALENT DOLLAR

VALUE

This Section estimates the reduced energy consumption and

equivalent market value of that reduction resulting from the more fuel

efficient vehicles introduced following promulgation of the Federal Fuel

Economy Standards. The following paragraphs derive the reductions in energy

consumption and dollar equivalents for passenger cars and for light trucks

based on the on-road fuel economy achieved by the Nation's motorists and as

59
measured in the On-Road Survey. Estimates are made for the total fleet for

the model years studied, and also on a per vehicle basis. For passenger

cars, reduced fuel consumption and dollar value estimates are extended to

cover Model Years 1982 through 1985.

2.8.1 REDUCED FUEL CONSUMPTION FOR PASSENGER CARS

Federal fuel economy standards for passenger cars began with the

1978 Model Year. Therefore Model Year 1977 is taken as the base year on

which to compute estimates of reduced fuel usage.^a For purposes of estimating these reductions, the following criteria and simplifying assumptions

are used:

(1) The mean total miles traveled (i.e., lifetime vehicle miles)

per passenger car is 85,730; this includes mileage of fleet

and business use vehicles which were not sampled in the ORFES

survey. The lifetime mileage is also a function of the

average vehicle miles traveled for a given vehicle age, x,

times the probability of survival of the vehicle to age x.

(This incorporates the "scrappage rate" of vehicles over

time). The basis for this lifetime estimate of per vehicle

miles traveled is given in Appendix D.20

As previously stated in this report, fuel economy increases may result

from market forces as well as from CAFE standards.

2 0 The estimate of 85,730 miles, per average passenger car, lifetime, is

considerably less than most all prior studies and surveys have assumed. The

primary basis for this lower estimate is the odometer data collected in the

ORFES survey and as analyzed in Chapter 3 and Appendix D.

60
(2) The age distribution of the passenger car fleet ranges from

zero to twenty years, with the survival probability for a

given vehicle being a decreasing function of its age.^1

(3) The total U.S. sales of passenger cars (including both

domestic and import vehicles) for a given model year is

approximately equal to the total U.S. sales of passenger cars

for that.same calendar year.22

Using these assumptions and the data from Table 2-1, the reduction in energy

(fuel) consumption is computed as follows:

For Model Year 1978, the reduction in fuel use per vehicle,

compared to the 1977 Model Year, is merely the decrease in fuel consumption

rate per mile (the reciprocal of mpg) for the newer vehicle times the miles

the average vehicle will travel in its lifetime, or:

gal. - gal. x 25,730 ml. * 475 gal.

15.2 mi. 16.6 mi. vehicle . vehicle

The total reduction in fuel consumed for Model Year 1978 is then the product

of the per vehicle reduction and the total number of vehicles in the

original (i.e., new) Model Year 1978 fleet. This is:

11,261,569 vehicles x 475 gal. = 5.346 x 109 gallons

vehicle

s 5.35 billion gallons

2

1 See Appendix D.

22 Sales by calendar year have been used. Sales figures used are taken from

"Wards Automotive Yearbook," 1978 through 1982 editions. Total U.S.

passenger car sales, domestic and import, for the five Model Years

1977-1981, respectively, are: 11,168,708; 11,261,569; 10,647,442;

9,976,535; 8,504,686. '

61
Similar computations for Model Years 1979, 1980, and 1981 yield

the following estimates of reduced energy consumption. All estimates are

based on Model Year 1977 as the base year:

1979 Model Year: total reduction = 7.29 billion gallons

per vehicle reduction = 685 gallons

1980 Model Year: total reduction » 13.51 billion gallons

per vehicle reduction = 1354 gallons

1981 Model Year; total reduction s 13.81 billion gallons

per vehicle reduction = 1624 gallons

The cumulative reduction in fuel consumption, both fleet total and

per vehicle average, for the four model years covered by the on-road survey

are:

Total reduction for four model years = 39.96 billion gallons

Average per vehicle reduction = 989 gallons

The cost equivalent of the above reductions in fuel use can be

estimated by assigning an average cost per gallon of fuel conserved and

aggregating these costs over the average lifetime vehicle miles. Since

annual vehicle miles traveled vary with vehicle age (more specifically the

odometer data in Chapter 3 show that yearly vehicle miles decrease rather

markedly with vehicle age, especially after the first few years of vehicle

life) and since the real price of gasoline is projected to increase over

62
time, it is therefore necessary to estimate reduced fuel costs per each year

of vehicle life. Finally since a portion of the reduced fuel consumption

will occur in the future, it is customary to discount such costs to arrive

at their present value.

For each vehicle of a given model year, the following formula was

used to determine the estimated, lifetime dollar equivalent value of the

reduction in fuel used:

20

Dollar value (per vehicle) = ) (.WT)i PCS^ FS Ci Dj (1)

Where,

= average annual vehicle miles traveled for a vehicle of age

i, where 20 years is considered the maximum age that a

vehicle can attain

- probability that a vehicle will survive to age i

FS = per vehicle reduced fuel consumption in gallons per mile

driven

Ci = estimated cost, in dollars, per gallon of fuel for year i

D| = discount factor for year i

63
The total dollar equivalent for a given model year (J) is then merely the

per vehicle dollar value, as estimated from the above equation, times the

total number vehicles sold in that model year or

20

Dollar value (Model Year) = Nj ) (VMDj P(S)i FS Cj Dj (2)

Where,

NA = total number of vehicles sold in Model Year j and the remaining

factors are as defined in (1) above.

A 10 percent discount rate23 has been used and all estimates are

expressed in terms of 1984 dollars. Appendix D contains further data and

information on the computation of the dollar equivalent estimates, including

references for pertinent data sources such as the Department of Energy for

price projections of gasoline, and the Department of Commerce for data on

fleet trucks.

2 3 OMB Circular No. A-94, March 27, 1972.

64
Applying the above methodology for estimating the dollar value of

reduced fuel consumption yields the following estimates for each of the four

model years for the reduced fuel consumption values computed in the

preceding section:

1978 Model Year: total dollar value = $6.63 billion

per vehicle dollar value = $606

1979 Model Year: total dollar value » $9.33 billion

per vehicle dollar value = $876

1980 Model Year: total dollar value = $16.30 billion

per vehicle dollar value = $1,634

1981 Model Year: total dollar value * $15.30 billion

per vehicle dollar value • $1,799

Aggregating the above estimates, the total dollar value due to

increased fuel efficiency for the four model years is:

$47.76 billion, or $1,182 per vehicle

Estimates of reduced fuel consumption and dollar equivalents to

this point are lifetime vehicle estimates for the first four model years of

passenger cars subject to the Federal fuel economy regulations. Estimates

have been restricted to this portion of the fleet since the survey only

included Model Year 1977 through 1981 vehicles. However, since the present

fuel economy standards extend to 1985 and beyond, and the standard levels

for each remaining year are known, the present survey provides complementary

information (in the form of on-road fuel economy vis-a-vis CAFE levels)

which can be used to project similar estimates beyond the Model Year

1978-1981 fleet.

65
The following calculations project reduced fuel consumption and

dollar equivalent through model year 1985. Assumptions used in these

projections-are the same as those used in the preceding calculations, plus

the following additional assumptions:

(1) An average annual sales volume of 10 million vehicles.

(2) The total U.S. passenger car fleet (both domestic and Import

vehicles) CAFE will average 26.0 mpg for each Model Year,

1982 through 1985.24

(3) Actual on-road fuel economy will continue to remain below

CAFE levels by approximately 15 percent, the same as the

average noted in the Model Year 1978 through Model Year 1981

vehicles covered in this survey.

The rationale for this assumption is as follows: The overall fleet CAFE,

for Model Year 1982 was 26.1 mpg. For Model Year 1983, it fell slightly to

25.9. Certain large manufacturers have had to rely on carry-forward/carryback credits in order to meet 1983 CAFE standard levels. Without these

credits manufacturer CAFE's would have been low by as much as 2.2-2.5 mpg.

More recent trends are for customers to purchase increasing numbers of

larger vehicles which are less fuel efficient. NHTSA has recently (October

1985) amended the level of the 1986 model year standard for passenger cars

from 27.5 mpg to 26.0 mpg. Sales of diesel-powered vehicles (which show

marked improvement in fuel economy over generically similar gasoline engine

vehicles) have greatly diminished from their peak sales period in 1981.

General Motors recently dropped the diesel engine option from essentially

all of its passenger car lines. Petroleum supplies continue to remain

abundant with prices also remaining relatively stable. Collectively, these

factors are believed to offer strong support that overall fleet CAFE levels

will not exceed 26.0 mpg, average, per year, 1982 through 1985.

66
Using these assumptions, the reduction in fuel consumption, per each year,

1982-1985, is computed as follows:

1977 fleet fuel consumption, per mile per vehicle = .065789 gal.

(from earlier calculations).

1982-1985 fleet fuel consumption, per mile per

vehicle =

 1

26.0 ml. x .85

gal.

= .0452488 gal./mi.

Per vehicle reduction, 1982-1985 fleet over 1977 fleet a

.065789 gal. -.0452488 gal.

mi. mi.

= .0205402 gal./mi.

Reduction in fuel usage, lifetime, 1982-1985 vehicle =

.0205402 gal, x 85,730 mi.

mi. vehicle

= 1,761 gal.

vehicle

Reduction in fuel usage, lifetime, Model Year 1982-1985 fleet

1,761 gal, x 4 x 107 vehicles

vehicle

7044 x 1O7 gallons

70.44 billion gallons

67
The cost equivalents of these reductions in fuel consumed, computed as

before for 1978-1981 models are:

1982 Model Year: total dollar value = $17.64 billion

per vehicle dollar value * $1,784

1983 Model Year: total dollar value = $16.21 billion

per vehicle dollar value = $1,621

1984 Model Year: total dollar value s $14.61 billion

per vehicle dollar value » $1,461

1985 Model Year: total dollar value - $13.48 billion

per vehicle dollar value = $1,348

Total dollar value, total 1982-1985 fleet = $62.14 billion

Finally, by adding to these totals the reductions in fuel consumption and

dollar equivalents previously computed for the 1978-1981 fleets, it can be

stated that the estimated reductions in fuel consumption and dollar

equivalents, lifetime, for all Model Years 1978-1985 of passenger cars,

subject to Federal Fuel Economy Standards are:

a

Per Vehicle:

Reduced fuel consumption = 1,373 gal.

Dollar value = $1,367

Total Fleet (Model Years 1978-1985):

Reduced fuel consumption = 110.40 billion gallons

Dollar value = $109.90 billion

68
2.8.2 REDUCED FUEL CONSUMPTION FOR LIGHT TRUCKS

Federal standards for light trucks took effect in 1979, one year

later than for passenger cars. Therefore, Model Year 1978 is taken as the

base year from which to compute estimated reductions in fuel use. The same

criteria and assumptions used for passenger cars are used here for light

trucks with one minor exception, the average lifetime miles for trucks (see

Appendix D) is slightly less at 85,427. Calendar year vehicle sales were

taken from Wards Automotive Yearbooks.25 The sales data on trucks were not

as detailed as those for passenger cars. Therefore, certain minor

adjustments had to be made. The resulting numbers are shown in Table 2-18.

TABLE 2-18

CALENDAR YEAR SALES OF LIGHT TRUCKS, MODEL YEARS 1979-1981

MODEL YEAR

Drive

Configuration 1979 1980 1981

Two-Wheel Drive 1,484,802 1,994,363 1,823,977

Four-Wheel Drive 255,934 450,267 369,495

For Model Year 1979, the sales figures are for trucks with GVWR of

6,000 pounds or less, while for 1980-1981, the figures are for trucks with

GVWR up to 8,500 pounds.

25 Footnote 26, Op. Cit.

69
Using data from Tables 2-11 and 2-18, the fuel reductions and

dollar equivalents are estimated in the following computations. Estimates

are made separately for two-wheel drive and four-wheel drive configurations,

with computation procedures similar to those used for passenger car fuel

reductions and dollar equivalent estimates.

2.8.2.1 REDUCED CONSUMPTION FOR TWO-WHEEL DRIVE TRUCKS

For Model Year 1979, the reduced fuel consumption per vehicle,

compared to the 1978 base year, is given by:

gal. - gal. x 85.A27 mi. • 179 gal.

15.2 mi. 15.7 mi. vehicle vehicle

The total reduction for the 1979 fleet over the 1978 fleet is

therefore:

1,484,802 vehicles x 179 gal. * 0.2658 x 109 gallons

vehicle

s 0.27 billion gallons

Similar computations for Model Years 1980 and 1981 yield the

following estimates of energy reduction, based on Model Year 1978 as the

base year.

1980 Model Year: total reduction = 2.31 billion gallons

per vehicle reduction - 1,159 gallons

1981 Model Year: total reduction = 2.41 billion gallons

per vehicle reduction = 1,321 gallons

70
Aggregating the above estimates, the lifetime reduction in fuel

consumption for two-wheel drive light trucks for Model Years 1979 through

1981 is found to be:

Total fleet reduction = 4.99 billion gallons

Per vehicle fuel reduction = 940 gallons

Converting the above two estimates to dollar equivalents, using

the same criteria and assumptions as for passenger car yields:

Total fleet value = $5.41 billion

Per vehicle average value = $1,020

2.6.2.2 REDUCED CONSUMPTION FOR FOUR-WHEEL DRIVE TRUCKS

For Model Year 1979, the fuel reduction per vehicle compared to

the 1978 base year, is given by:

gal. - gal. x 85,427 ml. * -387 gal.

13.7 mi. 12.9 mi. vehicle vehicle

71
Since the estimate for the 1979 fleet is negative, relative to the 1978

fleet, no reduction is estimated for the 1979 four-wheel drive light truck

fleet. Rather there is an estimated decrement of:

(255,934 vehicles x (-387 gal. ) = -0.10 billion gallons

vehicle

Using the same procedures, fuel reductions for the 1980 Model and

the 1981 Model Year four-wheel drive light truck fleets are computed to be:

1980 Model Year: total reduction = 0.30 billion gallons

per vehicle reduction = 664 gallons

1981 Model Year: total reduction s 0.41 billion gallons

per vehicle reduction = 1,108 gal.

Accumulating the above model year estimates the total reduction in fuel use

for four-wheel drive light trucks for Model Years 1979 through 1981 is:

Total reduction = 0.61 billion gallons

Per vehicle reduction = 566 gal.

72
In dollar equivalent values, the estimates are:

Total dollar value * $0.66 billion26

Per vehicle value = $610

2.8.3 REDUCED FUEL CONSUMPTION, LIGHT VEHICLE FLEET

By aggregating results from the previous sections on passenger

cars and light trucks, total estimates for the entire light vehicle fleet

are obtained. These are the total estimated reductions in energy

consumption and dollar equivalent values (vehicle lifetime) resulting from

the more energy-efficient passenger cars and light trucks produced from the

beginning of the Federal Fuel Economy Standards (Model Year 1978 for

passenger cars; Model Year 1979 for light trucks) through the 1961 Model

Year. The base year for these estimates is Model Year 1977. These

estimates are summarized in the following tables:

2 6 These estimates may be conservative since the on-road survey did not produce

estimates for import four-wheel drive trucks for Model Year 1979. These

vehicles due to their considerably higher fuel economy would raise the

overall (domestic plus import) fleet average above that of the domestic

vehicles used in the estimate. On the other hand, the estimates are likely

overstated for 1980-81 due to the fact that the baseline period is

representative of only domestic vehicles, whereas the 1980-81 periods

include both domestic and import vehicles.

73
TABLE 2-19 (a)

TOTAL REDUCTION IN FUEL CONSUMPTION AND

EQUIVALENT DOLLAR VALUE--PASSENGER CARS AND LIGHT TRUCKS

REDUCED FUEL DOLLAR

VEHICLE TYPE CONSUMPTION (billion gals.) VALUE (billions)

Passenger Car 39.96 $47.76

Light Trucks:

Two-wheel Driv

Four-wheel Drve

TOTAL SAVINGS 45.56 $53.83

TABLE 2-19 (b)

PER VEHICLE REDUCTION IN FUEL CONSUMPTION AND EQUIVALENT

DOLLAR VALUE - PASSENGER CARS AND LIGHT TRUCKS

REDUCED FUEL DOLLAR

VEHICLE TYPE CONSUMPTION (gals) VALUE (dollars)

Passenger Cars 989 $1,182

Light Trucks:

Two-wheel Drive 940 1,020

Four-wheel Drive 566 6_H3

Overall Average 974 $1,146

74
2.6.4 DISCUSSION OF REDUCED FUEL CONSUMPTION AND DOLLAR EQUIVALENT

ESTIMATES

It is customary in the Agency's typical evaluation studies of its

major regulations to estimate the benefits attributable to such regulations

together with the costs of implementing the regulations. This provides a

basis for comparing the costs and benefits or a basis for assessing

cost-effectiveness of the given regulation.

Due to the pervasive scope and complex nature of the motor vehicle

changes made in the drive for greater fuel efficiency, cost estimates of

these changes were not made. In addition to technological changes such as

diesel engines and improved transmissions, essentially all major domestic

carlines were redesigned and "downsized". While specific cost i stimates

have not been made, the impact and effect of the changes can be said to be

large indeed, perhaps one of the greatest changes in the history of the

automotive industry and one whose costs have variously been said to be in

the several billions of dollars.

As to the crediting of the reduced fuel consumption (i.e.,

benefits) estimated in this report to the Federal fuel economy regulations,

this is also not a straightforward exercise. The fuel economy regulations

took effect in Model Year 1976 (calendar year 1977) for cars and Model Year

1979 (calendar year 1978) for light trucks. During the mid-1970's, however,

following the Arab oil embargo, a shift in market demand for more

fuel-efficient vehicles emerged. The "second oil shock" of 1979 increased

the importance of this factor.

75
The following statements are quoted from the Secretary of Commerce's annual

report27 to Congress on the Chrysler Corporation Loan Guarantee Act of 1979

(Section 126, P.L. 96-185):

"These trends (i.e., a fundamental shift in consumer

demand toward smaller, more fuel-efficient vehicles,

etc.) emerged in the mid 1970s, but did not present

serious challenges to U.S. auto manufacturers until a

second round of oil price shocks in 1979 fundamentally

altered the competitive environment in the world motor

vehicle industry."

"In the United States in particular, gasoline prices

rose sharply from 1979 to 1961 and led to a dramatic

shift in consumer demand in favor of smaller, more

fuel-efficient automobiles "

"Virtually overnight, the small car share of the U.S.

market Jumped from 27 percent in 1979 and increased to

61.5 percent in 1981."

2 7 "The U.S. Automobile Industry, 1983, Report to the Congress from the

Secretary of Commerce, December 1984.

76
While no meaningful cost versus benefit comparison28 can be made of

the CAFE Standards per se, the estimates of the reduction in energy consumed

and dollar equivalent value derived in this study (45.6 billion gallons of

fuel; $53.8 billion) are considered conservative for the following reasons:

(1) The estimates only include vehicle model years through 1981; design and

technological changes implemented through 1981 have been carried forward in

many instances to subsequent years which means that additional benefits will

accrue as a result of those changes. (2) The estimates begin with the 1978

model year; they, therefore, exclude the 1977 full-sized GM cars which

represented the first portion of the fleet to be "downsized" in the drive

for greater fuel economy.

2 8 While the usual cost versus benefits comparisons for the CAFE standards per

se cannot be made, NHTSA, as part of its Regulatory Impact Analysis of each

CAFE standard promulgated, has analyzed the cost effectiveness of fuel

efficiency improvements available at that time to the manufacturers. The

cost effectiveness of fuel efficiency improvements is defined as the

estimated retail price increase to consumers, of the vehicle modifications,

versus the present discounted value of fuel saved over the vehicle's

lifetime. These analyses showed that cost-effective fuel efficiency

improvements were available.

These analyses were "before the fact" (i.e., conducted prior to the actual

production and sale of the vehicle) whereas the analysis in the study is

"after the fact," covering vehicles after they have been introduced into the

Nation's fleet and have accumulated real-world experience.

77
CHAPTER 3

ANALYSIS OF SURVEY RESULTS OF VEHICLE MILES TRAVELED

3.0 INTRODUCTION

The original design of the On-Road Fuel Economy Survey (ORFES) did

not have as one of its primary objectives the estimation of vehicle miles

traveled (VMT). The major emphasis was on the estimation of on-road fuel

economy. However, it was recognized early in the project that the

collection of actual odometer readings on a large, national probability

sample of vehicles would also provide a basis for estimating vehicle miles

of travel, and that such information could be a second important use of the

survey data. Travel data are also of considerable interest to NHTSA as well

as to several other agencies. While there have been prior studies and

surveys of the average and yearly travel of motor vehicles, as far as is

known, none have been based on actual vehicle odometer readings. These

former studies have relied primarily on data in the form of subjective

estimates by vehicle owner/drivers as to the total miles a given vehicle was

driven in a particular period, typically a year.

It will be recalled that the questionnaire design, a fuel-mileage

log, requested respondent reporting for a one-month period, of not only the

amounts of fuel purchased and other data, but also the actual odometer

readings, for the sampled vehicle, at each such fuel purchase. These

odometer readings, which were necessary to accurately develop fuel economy

estimates, are used in this chapter to estimate vehicle miles of travel,

78
both on an annual basis, by the age of the vehicle, and on a total, or

overall, vehicle lifetime basis, for the given model year (or vehicle age)

groups represented in the on-road survey.

3.1 METHODOLOGY FOR ESTIMATING VEHICLE MILES TRAVELED

The methodology used to develop the VMT estimates was as follows:

(1) The respondent-reported odometer readings of each vehicle were

assumed to represent the total accumulated (i.e., lifetime)

miles traveled for that vehicle as of the dates the vehicle

was sampled in the survey. The specific odometer reading used

for each vehicle in estimating VMT was the average odometer

reading for the one-month (nominal) period during which the

fuel-mileage diary record was kept for that vehicle. The

average here was defined as the arithmetic mean of the lowest

and highest odometer readings for the reporting, or diary

period for each vehicle. Symbolically,

(D

79
where,

Oi « average odometer reading for ith vehicle in

survey

1 * initial odometer reading for sample period

(typically one month) for ith vehicle

f - final odometer reading for sample period for

ith vehicle

(2) For each model year, or age group of vehicles, the overall

average odometer reading was simply the weighted arithmetic

mean of the odometer readings as defined in (1) above, using

as weights the actual numbers of registered vehicles1 in the

population as described in the previous chapter on fuel

economy. ___

The formula for computing the average odometer reading for a

given model year (or age group) stratum is given by:

K

0 age (j) - \W h On (2)

• h - 1

1 As previously stated in the Chapter on Fuel Economy, the number of

vehicles in the national fleet, or populations, were taken from the

annual registration files maintained by R. L. Polk Company.

80
where,

0 age {j) - overall average odometer reading for Jth

model year group,

Oh « average odometer reading for nth

stratum

Wn • proportion of vehicles in stratum h,

relative to the total number of

vehicleB in the overall (jth)

group.

In the above formula (2), 0^ is given by:

°h

where 0^ is given by (1) and n is the number of sample

vehicles in substratum j. The Wj are weights corresponding

to the proportion of vehicles in each substratum relative to

the total number of vehicles in stratum h.

(3) Since the vehicles were sampled throughout the entire twelve

months (January through December) of Calendar Year 1983, the

average odometer reading for each model year group, as defined

in formula (2), above, was assumed to represent total lifetime

vehicle miles traveled as of July 1, 1983, or the midpoint of

the calendar year in which the data were collected.

(4) The average age of a given model year group of vehicles is

estimated by assuming that sales of vehicles of each model

• year begin on October 1 of the previous calendar year and

continue for approximately 14 months. Sales typically extend

over more than a 1 year or 12-month period due to year-end

81
sales of "left-over" or previous aodel year vehicles at the

beginning of a new model year. Sales data indicate that

vehicle sales per month over this 14-month period are

distributed somewhat unevenly. The method of estimating

average vehicle age as of the July 1, 1963, mid-point of the

survey was to compute a weighted average age using monthly

vehicle sales data. Model year 1977 sales were chosen as

typical and data together with computation methods are shown

in Appendix B.

Using the above assumptions, average odometer readings were

computed for each of the 5 model year/age groups of vehicles. Computations

were made by vehicle type (car, truck), size class, fuel type (gasoline,

diesel), and number of drive wheels (trucks only). M l computations are

weighted arithmetic means using actual counts of registered vehicles as

described in the above paragraphs. As stated above, the odometer reading of

each vehicle at the point at which the vehicle is sampled, in the survey is

assumed to represent the total miles traveled by that vehicle at that point

in the life of the vehicle. Therefore, the computations of odometer

readings presented and discussed in the following sections of this chapter

will be referred to as vehicle miles traveled or simply VMT.lt should be

remembered that the survey only included privately-owned vehicles, and did

not include passenger car fleets, i.e., rental, business, etc. Odometer

readings from approximately 9,000 total vehicles were analyzed. Sample sizes

for each of the five model years (including both cars and trucks) ranged

from 1,084 for 1977 models to 2,662 for 1981 models.

82
3.2 VEHICLE MILES TRAVELS? ESTIMATES

3.2.1 OVERALL ESTIMATES BY MODEL YEAR AND VEHICLE TYPE

Table 3-1 displays the average (i.e., per vehicle) total vehicle

miles traveled, as of the July 1, 1983, midyear point of the survey as

discussed above. Estimates are shown for passenger cars and for light

trucks for each of the 5 model years represented in the survey.

Of special interest is the extremely close correspondence in miles

traveled between the 2 vehicle types. So close is this agreement that the

question of whether any statistically significant difference exists between

the VMT for cars and light trucks is essentially a moot point. Certainly,

no practical significance exists. The two vehicle types can be considered

as one general class and overall estimates for this combined group are shown

in the third column of the table.

TABLE 3-1

TOTAL VEHICLE MILES TRAVELED, AS OF JULY 1, 1983,

BY TYPE OP VEHICLE AND MODEL YEAR

Model

Year

1981

1980

1979

1978

1977

Passenger

Cars

28,

38,

46,

53,

59,

776

579

838

212

034

Light

Trucks

28,573

39,607

48,050

54,073

57,689

Overall

28,739

38,759

47,080

53,378

58,782

83
3.2.1.1 VARIABILITY OF OVERALL VMT ESTIMATES

The estimates of VMT given in Table 3-1 are Beans, or averages.

In a statistical survey of this type, it is also of interest to know

something about the reliability of the (mean) estimates, or something about

the variability of the data. Variability estimates can be developed for

surveys such as ORFES which are carried out according to probability

sampling methods.

Two generally accepted measures of variability are the sample

standard deviation and the standard error. The standard deviation is a

measure of the variability of all the individual observations that comprise

the sample, or, in this case, an indication of the vehicle-to-vehicle

variability in VMT. The standard error, on the other hand, is an indication

of the reliability, or precision, of the sample mean, or the average VMT.

Table 3-2 lists the sample standard deviation and the standard

error for each of the five Model Years for the combined (cars plus trucks)

vehicle classes of Table 3-1. Looking first at the standard deviation

column, it is seen that there is considerable variation in VMT among the

individual vehicles comprising each Model Year group. This variation ranges

from 14,109 miles for the 1981 vehicles to 23,784 miles for the 1977, or

oldest vehicles. In terms of differences in miles driven, these numbers

appear quite large, indeed.

84
•DXBLE 3- 2

09 •

STWEftRD DiVIATICN AND SWOVRD ERRCK5 PCR VWT

ESTOWTES EK VEHICLE MCDHL YBAR

Mxlel

Year

1977

1978

1979

1980

1981

Sample

Size (n)

1,084

1,471

1,722

1,975

2,662

Moan

\WT (x)

58,782

53,378

47,080

38,759

28,739

StandardV

Deviation (s)

23,894

23,116

19,487

18,379

14,109

StanaardJ^y

Error (S.E.)

841

631

549

430

301

Coefficient

of \feuriation (c.o.v.)

.405

.433

.414

.474

.491

Relative Stri.

Bror (R.S.E.) %

1.43

1.18

1.17

2.34

2.13

* Weighted, pooled standard deviation from individual stratum variances.

•* Weighted standard error from individual stratum standard errors.
A second way of viewing the variation among samples is via the

coefficient of variation (c.o.v.), which is defined as (*/£), and therefor*

is a measure of the degree of variation in VMT among the individual vehicles

relative to the mean VMT for that age group. Column 5 of Table 3-2 lists

the c.o.v.'s. Again, it is observed that the variation and VMT is quite

large, ranging from approximately 40 percent to nearly 50 percent, relative

to the mean VMT. While the actual magnitude of the variation in VMT appears

to increase with vehicle age, the opposite is true for the relative

variation, with the youngest vehicles showing the greatest variation,

relative to the mean VMT.

The standard errors for the mean VMT estimates of the five Model

Year groups are also shown in Table 3-2, column 7. The standard error gives

an indication of the variability of the sample mean. As the table shows,

the standard errors are quite small; relative to the mean, the standard

errors range from approximately 1 to 2 percent. Similar to the trends noted

for the standard deviation, it is seen that the magnitude of the standard

error increases for older vehicles whereas on a relative basis, the error is

larger for the newer vehicles. Since the standard error is inversely

related to the square root of the sample size, part of the reason for the

smaller standard errors for later model years is that larger sample sizes

were taken for newer vehicles.

86
Using data from Table 3-2, two additional statistics are presented

which provide additional information on the variability of the ORFES VMT

estimates. These statistics are: (1) the 95 percent confidence interval on

the mean VMT, and (2) the 95 percent x 95 percent tolerance limits on VMT

for individual vehicles in each of the model year groups. Both of these

statistics assume a normal distribution for the population VMT parameter,

and are shown in Table .3-3.

The 95 percent confidence limits from column 3 of the table

indicate that the mean estimates for VMT are quite precise. The width of

the intervals ranges from a low of approximately 1,200 miles (for 1981

vehicles) to a high of approximately 3,300 miles (for 1977 vehicles). The

interpretation of these intervals is that, in repeated samplings of

vehicles, such as conducted in ORFES, 95 percent of the intervals

constructed from the sample data would contain the true mean VMT for the

entire fleet population represented (e.g., 1978 vehicle fleet, 1979 vehicle

fleet, etc.).

87
TABLE 3-3

NINETY-FIVE PERCENT CONFIDENCE LIMITS AND TOLERANCE

LIMITS ON VMT BY VEHICLE MODEL YEAR

Model

Year

1977

1978

1979

1980

1981

Mean VMT

(X)

56,782

53,378

47,080

38,759

28,739

95% Confidence

Interval

57,134-60,430

52,141-54,615

46,004-48,156

37,536-39,602

28,149-29,329

95% x 95%

Tolerance Limits

10,263-107,301

6,221-100,535

7,327-86,833

1,266-76,252

-43*-57,521

* Considered a minor anomaly (VMT can't be negative)

88
Ninety-five x ninety-five percent tolerance limits on individual

vehicle VMT are listed in the last column of Table 3-3. Tolerance limits

refer to the VMT for each individual vehicle in the population as contrasted

with the confidence limits which refer to the mean VMT for all vehicles in

the population. The interpretation of tolerance intervals is that in

repeated survey samples of vehicles, such as conducted in ORFES, the 95

percent of the intervals constructed from the sample data would encompass

the VMT for 95 percent of the total vehicles in the population.

Once again, the great variation in VMT among vehicles within the

same age group is apparent. For example, the VMT among individual 1977

model year vehicles is seen to range over nearly 100,000 milesl Nineteen

seventy-seven vehicles were approximately 6.2 years old at the time of the

on-road survey. The other model year groups show similar wide ranges for the

VMT among individual vehicles. These data indicate that within each vehicle

age group there are a small percentage of vehicles which have accumulated

very high VMT, and also a small percentage which have been driven very few

miles.

The principal point that stands out in the above statistics is

that for each age group, the variability in VMT per vehicle is very large.

VMT per vehicle does not cluster around the mean VMT for a given age group,

but rather exhibits wide dispersion around the mean. The method used in

allocating the sample among strata (i.e., oversampling a few small strata in

order to increase the precision of the estimates for these strata) has the

89
effect of increasing the magnitude of the variance estimates. However this

effect is considered minor relative to the magnitude of the variance

estimates for VMT, as shown above.

3.2.2 ESTIMATES BY SIZE CLASS

Estimates of total miles traveled by vehicle size class are shown

in Tables 3-4 and 3-5 for passenger cars and light trucks respectively. A

general perusal of these tables indicates that little difference of a

practical nature exists due to vehicle size class for either cars or

trucks. Furthermore, this finding is true between two-wheel drive and

four-wheel drive trucks. For trucks, there is some indication of slightly

higher travel by vans, but the magnitude is not considered of practical

significance. For passenger cars, large station wagons appear to

accumulate somewhat higher mileage than other car classes, while compacts

and midsize cars seem to have been driven the least.

For the passenger car size classes an average rank order for the

five model years was computed. A "1" was assigned to the highest VMT within

each model year and an "8" to the lowest VMT. The average ranks appear in

Table 3-6.

90
TABLE 3- 4

TOTAL VEHICLE MILES TRAVELED

PASSENGER CARS BY SIZE CLASS

Size

Class 1981 1980

-MODEL YEAR1979 1978 1977

Mini 31,805 45,271 47,201 50,212 65,748

Subcompact 30,114 38,784 50,449 57,641 59,330

Compact 29,832 35,530 45,976 49,336 56,981

Midsize 26,558 37,394 44,004 50,419 55,693

Large 29,082 37,825 46,069 54,323 61,254

Small St.

Wagon 29,725 45,635 46,008 60,677 62,417

Midsize St.

Wagon 30,157 39,138 49,620 56,442 60,124

Large St.

Wagon 31,847 45,651 49,265 59,847 66,616

NOTE: Sample sizes range from 24 to 569 for each of the above year-size

class categories.

91
TABLE 3-5

TOTAL VEHICLE MILES TRAVELED

LIGHT TRUCKS BY SIZE CLASS

Size

Class

2-Wheel Drive

1981

MODEL YEAR

1980 1979 1978

Small Pickup 33,128

Standard Pickup 28,648

Special Purpose 27,127

Overall

4-Wheel Drive 29,362 37,862 43,592 51 ,952

1977

Small Pickup

Standard Pickup

Van

Special Purpose

Overall

2-Wheel Drive

4-Wheel Drive

31,

26,

31,

29,

28,

469

069

045

483*

393

34,

41,

43,

55,

40,

766

475

953

702*

197

47,418 •

47,809

51,857

53,062*

48,767.

54,169

51,997

59,322

40,243*

54,380

61,477

55,750

61,014

67,435*

58,242

40,

35,

38,

225

969

981

•*

**

43,592

**

**

51,952

57

52

**

,788*

,102

52,535

Sample siz e for each of the individual year-size class groups ranges from 20

to 170.

*Very small sample siz e (< 10)

**Not sampled

92
TABLE 3-6

AVERAGE VMT RANK BY SIZE CLASS, PASSENGER CARS

Size Class

Mini

Subcompact

Compact

Midsize

Large

Small Station Wagon

Midsize Station Wagon

Large Station Wagon

Average Rank

(All Model Years

3.6

3.B

7.0

7.4

5.4

3.6

3.6

1.6

93
This table does indicate, as previously stated, that large station

wagons tend to accumulate higher mileage while compacts and midsize cars

accumulate lower mileage. Statistical tests on the data for the 1977 Model

Year indicate that the only significant differences in VMT are between the

large station wagon/mini classes and the compact/midsize classes.

Practically speaking, however, it is doubtful whether such differences are

meaningful. The difference noted for the 1*977 vehicles are for the total

VMT accumulated over the life of the vehicles which are slightly more than

six years old on the average. On a per year basis, the difference in VMT

would be much less.

3.2.3 ESTIMATES BY TYPE OF FUEL

Since fuel costs vary appreciably between gasoline and diesel

vehicles, it was considered of interest to investigate whether type of fuel

was associated with the amount of miles traveled. Tables 3-7 and 3-8

summarize a comparison of total VMT for the common vehicle classes (e.g.,

classes where both diesel and gasoline engines were represented) and for

both cars and trucks. This comparison reveals that, indeed, a difference

exists due to fuel type. Diesel vehicles show consistently higher mileage

than vehicles powered by conventional gasoline engines and this difference

is considerably greater for passenger cars than for light trucks. It also

appears that within cars, size class may be a factor as well with small

94
subcompact cars showing greater excess of travel diesel versus gasoline,

than for midsize and large cars. The reason(s) for the higher travel for

diesel vehicles is believed most likely due to the lower fuel cost per mile

driven for diesel vehicles, although other factors such as purpose /type of

driving could also be involved. Chapter 2.0, Section 2.5 showed estimates

of the on-road advantage in fuel efficiency for diesel vehicles over

gasoline vehicles.

SIZE

TABLE 3-7

VEHICLE MILES TRAVELED - PASSENGER CARS

GASOLINE VERSUS DIESEL

- MODEL YEAR -

CLASS

Diesel-Subcompact

Gas-Subcompact

Diesel

(Midsize, Large

Midsize/Large

Station Wagon)

Gas (Midsize,

Large, Midsize/

Large Station Wagon

1981

41,390

29,543

34,998

26,941

1980

55,707

37,962

45,298

37,385

1979

64,073

50,117

54,863

45,239

1978

*

*

62,682

54,899

•Insufficient sample size

95
TABLE 3-8

TOTAL VEHICLE MILES TRAVELED

GASOLINE VERSUS DIESEL

LIGHT TRUCKS

SIZE

CLASS

Diese l

Small

Gas

Small

Pickup

Pickup

19B1

34,445

30,911

MODEL

1980

53,043*

34,117

YEAR

1979

No D

. -

1978

No Diesels Available

Diesel

Standard Pickup 33,625 43,383 48,446 56,327

Gas

Standard Pickup 25,930 41,360 47,789 51,195

Sample sizes range from 21 to 146 for each year-size class group

•Sample size < 10

96
3.2.4 ANNUAL VMT ESTIMATES

Using the survey estimates of vehicle travel given in the previous

sections, estimates can be made of the annual VMT as a function of the age of

the vehicle. The overall estimates (i.e., Column 4) given in Table 3-1 are

chosen as the basis for estimation of annual VMT. These data are selected

since the individual estimates for passenger cars and trucks are extremely

similar, and also since the total sample size for each age category will be

the largest, thereby decreasing the statistical variability of the estimates.

The annual VMT estimates thus developed will apply to the total U.S. Fleet of

light vehicles including both passenger cars and light trucks.

As a first step in the estimation process, the data from Table 3-1

were plotted to give a visual picture of the relationship between VMT and

vehicle age. This is done in Figure 3-1 with VMT as the ordinate and vehicle

age as the abscissa. The average ages of the model year groups of vehicles

at the July 1, 1983, mid-year point (the point for which the average model

year odometer readings are computed are:

Average Vehicle Age

Model Year on July .1,,, 1983

1981 2.2 years

1980 3.2 years

1979 4.2 years

1978 5.2 years'

1977 6.2 years

(NOTE: see Appendix B for explanation of average age computation)

97

Note from Figure 3-1 that the five average odometer readings as computed

from the survey data form a very smooth function. A curve can be drawn

through the five points with essentially rui discernable dispersion, or

scatter, of any point from the curve. The function is definitely

curvilinear with a declining slope which indicates a decline in annual VMT

with the age of the vehicle.

The curvilinear plot of the data suggest that a logarithmic

function might fit the points reasonably well (i. e., be used to explain the

relationship between VMT and vehicle age). The following function was

fitted:

y = a + b log x

where y represents VMT in miles as indicated by the vehicle odometer

readings),

x represents vehicle age in years, and a and b are constants to

be determined.

Resulting computations showed that indeed, the logarithmic

function fits the data quite well. Figure 3-2 displays the fitted function

which is:

y (miles) = 5,445 + 66,996 log x (age)

99

The fitted curve is plotted in Figure 3-2 for the vehicle age

range 2.2 years through 19 years. The coefficient of determination

(r2Xy) and the standard error of the estimate (Sy.x) for the fitted

equation are:

r

2

xy = .99945,

Sy.x = 302.25 miles

These statistics indicate a very close fit for the VMT curve.

Over 99.9 percent of the variation in the dependent variable, y, or VMT,

is explained by the function. Computing 2-standard error limits

(equivalent to 95 percent confidence limits) for y give +_ 590.45 miles,

a very small range of error.

A second view of the close fit of the equation is afforded by

Table 3-9 which compares the dispersion between the observed and

predicted values of VMT.

101
TABLE 3- 9

COMPARISON OF OBSERVED AND PREDICTED VMT

VMT

x (yrs.)

2 . 2

3 . 2

4 . 2

5 . 2

6 . 2

Observed

28,739

38,759

47,080

53,378

58,782

Predicted

28,386

39,288

47,200

53,414

58,532

Difference

(Obs.-Pred.)

353

-529

-120

- 36

250

Percent

Difference

1.2

-1.4 '

-0.3

-0.07

0 . 4

Again, the high degree of fit is demonstrated with the relative

difference between the observed VMT and predicted VMT from less than 1/10 of

one percent to 1.4 percent. The actual data points were not plotted on

Figure 3-2 (as is often done in typical curve-fitting analyses) because they

would be virtually indistinguishable from the line itself.

Finally, 95 percent confidence intervals for VMT were computed for

each of the five sampled vehicle age points. These are shown on Figure 3-2.

The width for each of these intervals, from vehicle age 2.2 years to 6.2

years respectively, are: 2,136 miles, 802 miles, 349 miles, 1,041 miles,

and 1,664 miles.

NOTEs The very good fit of the above function may, in some respect, be

due to the fact that the five VMT data points represented means

of reasonably large samples rather than individual VMT readings.

Nevertheless, the near-collinearity of the observed points apart

from the fitted equation is considered surprising, if not

remarkable.

102
The logarithmic function in Figure 3-2 is plotted over the vehicle age

range of 2.2 years (the newest vehicles covered in ORFES) to a vehicle age

of 19 years. While the survey only included vehicles up to 6.2 years of

age, it is considered reasonable to extend the curve2 for the following

reasons:

(1 ) The statistical fit of the curve is very good, as

confirmed by the above measures of goodness of fit.

(2) The actual data points, apart from a curve-fit, are so

well defined that a curve can be simply hand-fitted

through them with essentially no discernable dispersion,

or scatter (see Figure 3-1).

(3) The form of the VMT-age function appears to be definitely

curvilinear, with a continuously declining slope. This

implies that VMT decreases as the age of the vehicle

increases. This decreasing rate of VMT with vehicle age

is reasonable, and in accord with intuition. Vehicles

wear out—not only due to mileage, but also simply due to

environmental degradation and decay (i.e., rust,

corrosion, hardening/cracking of rubberized and plastic

components) which in general affects all systems and

Extension of the VMT-Age curve is made with full recognition of the

long-standing general statistical caution against extrapolation beyond

the bounds of the sample data. One of the reasons for this caution is

that typically little or no a_ priori information is available

concerning the relationship of the fitted variables, beyond the range of

the empirical data. We have considerable a_ priori knowledge here

about the nature of the underlying process operating to define the

function, namely, that VMT decreases, in general, with vehicle age.

103
components of the vehicle. Thus, as vehicles age, it

seems quite logical that they are driven less due to

decreased vehicle reliability and increased cost of

operation.

That vehicles are driven less as they become older is generally

supported by other VMT surveys which are discussed later in this chapter.

Therefore, there is strong support for a VMT-vehicle age function

which has a declining slope.

An extension of the logarithmic function vehicles newer than 2.2

years does not fit well, since at a vehicle age of slightly less than one

year, the curve would intersect the x-axis. This indicates a VMT of zero,

and realistically for an average vehicle, zero mileage should coincide with

zero age. A visual review of Figure 3-2 indicates that the form of the true

function between age 2.2 years and zero years should be essentially linear,

since the extension of the function from 2.2 years must pass through the

origin. In keeping with the curvilinear relationship of the statistically

fitted function, it is considered reasonable to hand-fit the remaining

portion of the function over this short (zero-to-2.2 years) span such that a

slight degree of curvature is maintained. This has been done and appears as

the "dotted" portion in Figure 3-2.

104
3.2.4.1 . CUMULATIVE AND ANNUAL VMT, ESTIMATES BY VEHICLE AGE

Table 3-10 displays cumulative and annual VMT estimates based on

the fitte d curve in Figure 3-2. The cumulative miles are computed directl y

from the logarithmic equation for x = 2.2 years and greater, while for x <

2.2 years, the cumulative miles are read directl y from the graph. The

annual estimates are merely the result of subtraction (i.e. , annual VMT for

year "x" - cumulative VMT for year "x" minus cumulative VMT for year "x-1".)

To be noted is the continuous decrease in annual VMT with vehicle age. The

average 15-year-old vehicle has been driven approximately 85,000 miles.

TABLE 3-10

CUMULATIVE AND ANNUAL VMT ESTIMATES BASED ON

FITTED LOGARITHMIC CURVE

Age in CUMULATIVE ANNUAL

Years . VMT . VMT .

0 0 '

1 14,000 14,000

2 26,000 12,000

3 37,410 11,410

4 45,781 8,371

5 52,273 6,492

6 57,578 5,305

7 62,063 4,485

8 65,948 3,885

9 69,375 3,427

10 72,441 3,066

11 75,214 2,773

12 77,746 2,532

13 80,075 2,329

14 82,231 2,156

15 84,238 2,007

16 86,116 1,878

17 87,880 1,764

18 89,543 1,663

19 91,116 1,573

105
3.2.4.2 AVERAGE ANNUAL VMT ESTIMATE FOR TOTAL VEHICLE FLEET (ALL

AGES

Table 3-11 contains the data for estimating the average annual VMT

for the total vehicle fleet, all age groups of vehicles. The estimates are

derived from a weighted average (arithmetic) of the annual miles traveled,

by vehicle age as shown in column 4 of the table with the weights being the

number of total vehicles registered nationally, for each age group, as of

July 1, 1982, and as compiled by the R. L. Polk Company. The age groups

have been changed slightly to conform to the date on which the Polk figures

are compiled and to incorporate all vehicles in the U.S. fleet which are

less than 2 years of age. Again, the estimates are for all light vehicles

which includes both cars and light trucks. The estimated average annual

miles traveled for all vehicles (i.e., all vehicle age groups) appears at

the bottom of column 4 and is:

average annual VMT (all vehicles on-road) = 6,025 milesThis estimate as well as the marked decline in VMT with vehicle

age shown in Table 3-11 and Figure 3-2 differ considerably from prior

estimates of VMT as developed in various surveys and studies. A discussion

of these differences is given in the following section.

106
TABLE 3-11

DATA FOR COMPUTATION OF AVERAGE ANNUAL VMT, ENTIRE

U.S. FLEET OF PASSENGER CARS AND LIGHT TRUCKS

Age in

years

. 2

1.2

2 . 2

3 . 2

4 . 2

5.2

6 . 2

7 . 2

8 . 2

9 . 2

10.2

11.2

12.2

13.2

14.2 and

older*

OVERALL

TOTALS

No. o f Vehs. a

Registered

5,494,680 .

9,989,001

10,621,006

13,380,754

13,294,218

12,520,031

10,809,647

8,264,068

10,560,859

9,605,962

7,587,798

5,357,835

4,583,669

3,841,661

13,393,061

138,440,546

Pet. Totala

Registered

.0397

.0720

. 0767

.0967

.0960

. .0904

.0781

.0597

.0763

.0694

.0548

.0387

.0331

.0277

.0967

1.0060

Annual VMT

1,500

13,500

13,386

10,902

7,912

6,214

5,118

4,351

3,784

3,348

3,002

2,721

2,489

2,292

2,125

6,025

•Includes small number of unknown ages

a

 Sources R. L. Polk and Oanpany, NVPP File , July 1, 1982, FURTHER REPRODOCTIDN PRCHIBTrEO

tor
3.2.5 COMPARISON OF ORFES VMT ESTIMATES WITH OTHER SURVEY

ESTIMATED

Table 3-12 is a comparison of the VMT estimates from the On-Road

Fuel Economy Survey with VMT estimates from other past surveys. Note that

for the first two-to-three years, the surveys do not differ greatly as to

the VMT by age. However, beginning with the fourth year, the ORFES estimates begin to show considerable departure from the other survey estimates,

and generally show a marked decrease in annual VMT compared to the other

surveys, together with a much more pronounced rate of VMT decline with

vehicle age. Additionally, the average annual VMT for all vehicles for

ORFES is considerably lower at 6,025 miles, than the other surveys which

range from 10,000 to 11,000 miles.

As to possible reasons for this difference between ORFES and the other

surveys, perhaps the most likely candidate is the method of estimating

travel for each individual vehicle in the survey. As far as is known, the

method used in all prior surveys was to ask individual members of a sampled

household, "About how many miles did your household drive vehicle "A" in the

last year?" ORFES estimates, on the other hand, are based on the actual

odometer readings as recorded by survey respondents over a 1-month period

during which they kept a log of their fuel purchases. In the former case,

we have data which must be considered subjective, the degree of accuracy of

which is unknown. Odometer readings, in contrast, must be considered

objective in nature and, as far as is known, ORFES is the first instance

where odometer readings have been sampled on a nationally representative

basis. ORFES also used the national population of vehicles (privately

owned) as a sampling frame whereas the other surveys are based on a sample

from the Nation's households. The target population for both ORFES and the

108
TABLE 3-12

COMPARATIVE ESTIMATES OP AVERAGE ANNUAL MILES

PER AUrOOBILE3 BY AGE OF AUDOMDBIIE

Age i n

years

1

2

3

4

5

6

7

8

9

10

11

12

12

14

15

16

All , miles

1969 NETS

17,600

16,200

13,200

11,500

11,700

10,000

10,400

8,700

10,900

8,000

6,6003

11,600

1975 WCMS

13,565

14,805

11,115

11,mo

11,054

9,869

9,570

8,862

9,361

7,3O5c

10,626

1977 NPIS

11,794

13,396

13,380

12,107

11,307

10,694

10,517

9,532

8,658

8,812

7,i32d

10,307

1978 Cambridge

Systematics

10,360

12,910

12,720

9,910

12,530

9,390

10,230

9,300

8,570

8,670

6,770^

10,100

1983 NHTSA

CRFE3b

14,000

12,000

11,410

8,371

6,492

5,305

4,485

3,835

3,427

3,066

2,773

2,532

2,329

2,156

2,007

1,878

6,025

%ovBehold autos only.

includes light trucks

c

Inclu3es vehicles 10 years old and older.

^Includes vehicles 11 years old and older.

Secondary Source: Transportation Energy Data Book, Sixth Edition

U.S. Department of Energy

Original Sources: 1969 - U.S. Department of Transportation, Federal Highway

Administration, Nationwide Personal Transportation Study:

Annual Miles of Autanobile Travel, Report No. 2,

Washington, D.C., April 1972, p. 14.

1975 - Washington Ctenter for Metropolitan Studies, Lifestyles and

Household Energy Data, Washington, D.C., 1977.

1978 - Cambridge Systematics Inc., Cambridge, Mass., National

Travel Survey 1978, magnetic tape, prepared by the

National Science Foundation, 1979.

1977 - J. R. Kuanyak, QOMSIS Corp., 1977 Nationwide Personal

Transportation Study, Report 5: Household Vehicle

Utilization, U. S. Department of Transportation, Federal

Highway Administration, Washingtm, D.C., April 1981.

109
other surveys shown in Table 3-12 was the same—all privately-owned

vehicles. This fact perhaps accentuates even more the question of why the

results are so different.

One area that could cause travel estimates based on odometer readings

to be biased low is where odometer readings have been turned back or

otherwise tampered with. While available information does not allow an

estimate of the magnitude of bias due to this phenomenon, it is believed

that it would not be sufficient to explain a signficant amount of the

difference in VMT estimates between ORFES and the prior surveys.

In terms of comparisons of ORFES results with other data, one

other area is to be noted. As a part of its many highway-related

statistics, the Federal Highway Administration (FHWA) annually publishes

estimates of VMT. For 1983, the FHWA gives the following estimates3 for

passenger cars and light trucks:

passenger cars - 9,641 miles

light (single unit) trucks - 9,705 miles

The definition of light trucks differs between FHWA and the light

trucks samples in ORFES, so that a meaningful comparison is not possible.

However, for passenger cars, a comparison can be made.

3 "Highway Statistics", 1983, published by Federal Highway Administration,

U.S. Department of Transportation.

110
In making this comparison, it must be remembered that the ORFES

sampling, frame included only privately-owned vehicles, thereby excluding

fleet vehicles (business, rental, police, government, taxi, etc.). The FHWA

estimate is for all passenger cars, fleets included. The impact on VMT of

fleet vehicles, it seems, would have to be large, indeed, in order to offset

the large difference in the two estimates, of 6,025 miles for ORFES and

9,641 miles for FHWA.

One way to investigate the impact of fleets on average annual VMT is

to calculate the average annual VMT necessary for fleet vehicles.in order to

have the overall U.S. fleet (e.g., both private and fleet) VMT equal to the

FHWA estimate, or 9,641 miles per annum.

In order to do this, the simplifying assumption is made that all

fleet vehicles are 6.2 years of age, or younger. We next construct the

following equation:

.5496 (x) +.4504 (2,552 miles) = 9,641 miles

Here x is the average annual VMT for all U.S. fleet vehicles 6.2

years of age and younger. The proportion of total fleet vehicles in this

age bracket is .5496 as computed from column 3 of Table 3-11j .4504 is the

remaining portion of the total fleet or that portion over 6.2 years of age,

and 2,552 is the average annual VMT for this latter portion of vehicles as

computed from columns 3 and 4 of Table 3-11 (e.g., the population weighted

average VMT).

Ill
Solving the above equation gives:

x = 15,450 miles

Comparing 15,450 with the On-Road Survey estimate of 8,7804 implies

that the non-privately owned vehicles, assuming they comprise 17 percent^ of

all vehicles aged 6.2 years and younger, would have an average annual VMT, y,

given by:

.17y + (1 -.17) 8,780 miles = 15,450 miles

or

y • 48,015

4 The population weighted average annual VMT for vehicles aged 6.2 years and

younger, computed from columns 3 and 4 of Table 3-11.

5 pe r Transportation Energy Data Book, Edition 7, Oak Ridge National Laboratory,

ORNL-6050, issued June 1984, total fleet vehicles in 1982 numbered

approximately 10 million vehicles. This is approximately 17 percent of total

U.S. registered passenger cars aged 6.2 years and younger, based on R. L. Polk

data. Passenger cars are subsetted from all vehicles in column 2 of Table 3-11

in order to compute this fraction.

112
Thus, under the assumptions made above, fleet vehicle annual

travel would have to be 48,015 miles in order for the FHWA estimate of 9,641

miles annually for all vehicles to hold. This is five to six times the

average VMT (8,780) for privately owned vehicles of the same age as

estimated from the On-Road Survey. It is also twice the average annual

travel of 24,000 miles per fleet/business vehicle as given by Shonka6. The

estimate of 48,015 miles further implies that all fleet vehicles would have

to travel a total of 48,015 x 6.2 or nearly 300,000 miles average, during

their fleet lifetime! This would appear to be quite unrealistic.

Furthermore, available data on fleet vehicles also indicate that

the average age of fleet cars at time of trade-in or replacement by fleet

owners is only 2 to 2 1/2 years.7 At an average annual VMT of nearly 48,015

miles, as computed above, the average fleet vehicle at time of trade-in

would have been driven 120,000 miles! Again this is considered highly

unlikely due to the low remaining useful life and low resale value such

vehicles would possess. In all likelihood such vehicles have considerably

lower mileage at the time they are traded in.

6 Transportation Energy Data Book, Edition 7, cited in footnote 5/ to this

chapter. Secondary source: Annual Travel and Size of Fleet - D.B. Shonka,

"Characteristics of Automotive Fleets in the United States, 1966-1977,"

ORNL/TM-6449.

7 "Characteristics of Automobile Fleets in the United States, 1966-1977,"

D.B. Shonka, ORNL/TM-6449, September, 1978.

"The Use of Weighted Vehicle Miles Traveled in Estimates of Corporate

Average Fuel Economy", Internal Report by J. Thornton, NHTSA, July 1981.

(Data on vehicle age obtained from National Association of Fleet

Administrators, 1980).

113
Collectively, the above numbers offer rather strong support that

annual VMT for the U.S. fleet of passenger cars and light trucks both on a per

vehicle and overall fleet basis, are considerably lower than previously

indicated by existing prior surveys and studies.

114
CHAPTER 4

SURVEY METHODOLOGY AND DATA COLLECTIOH

4.0 INTRODUCTION

This chapter describes the methodology and data collection aspects

of the national survey which provided the data to support this evaluation,

study. As stated earlier in this report, the original primary objective of

the survey was to produce valid national estimates of the actual on-road

fuel economy for motor vehicles produced under the early years of the

Federal Fuel Economy Standards. Early in the survey implementation period,

the purpose of the survey was broadened to also include the estimation of

annual vehicle miles traveled (VMT). Survey issues discussed in the

following sections include: (1) The design of the survey, (2) The survey

instrument (questionnaire), (3) Data collection, (4) Data reduction and data

processing, and (5) Survey response and nonresponse topics, and (6)

Potential sources of error.

Actual implementation of the survey, including final design

aspects, sample selection, development of mean miles per gallon estimates

including weighting, and data reduction and processing was performed by a

national survey firm under contract to the National Highway Traffic Safety

Administration. The contractor also conducted an analysis of potential

nonresponse effects. The results of the survey implementation are

documented in a contractor final report to NHTSA.1

"On-the-Road Fuel Economy Survey: FINAL DATA COLLECTION REPORT," Submitted

to: National Highway Traffic Safety Administration, Office of Program

Evaluation by the National Opinion Research Center, 6030 South Ellis Avenue,

Chicago, IL 60637, University of Chicago, October 1984.

115
4.1 SURVEY DESIGN

The design of the survey was based primarily on the results of an

in-house pilot test conducted by NHTSA in 1979 which evaluated the questionnaire format and the effect of various other factors on the enhancement of

survey response. Prior to arriving at the final design, reviews were made

of two other major surveys designed to collect similar information on the

fuel consumption of motor vehicles.2 These reviews included both documentation concerning the two surveys, plus on-site discussions with officials

of the two sponsoring agencies. Minor modifications were made in the final

survey design as a result of recommendations of the winning proposal to the

competitive bidding action to obtain a survey contractor.

4.1.1 TARGET POPULATION AND SAMPLING FRAME

The vehicle population for which on-road fuel economy inferences

were desired was defined as all privately-owned passenger' cars and light

trucks of the 5 Model Years 1977 through 1981 in the United States. The

vehicle population was further defined as those vehicles produced by the 4

major domestic and 4 major foreign manufacturers: American Motors, Chrysler,

Ford, General Motors, Datsun/Nissan, Honda, Toyota and Volkswagen. The

population of interest excluded vehicles in fleets because it was deemed

operationally infeasible to obtain nationally representative fuel economy

data on these vehicles at the level of detail desired. This assessment was

2 "The Fuel Consumption Survey," Statistics Canada, Special Surveys Division,

3C-3 Jean Talon Bldg., Ottawa, Ontario.

"Residential Energy Consumption Survey," Energy Information Administration,

Office of Energy Markets and End Use, U.S. Department of Energy, Washington,

D.C.

116
made upon review of prior attempts to survey fleets for fuel economy. The

sub-population of import vehicles was confined to the four major companies

to simplify the sample selection and allocation and since these four

companies represent the large majority (approximately 75 percent) of the

total import vehicle fleets for the model years of interest.

The sampling frame chosen for the On-Road Survey was the U.S.

vehicle registration files maintained by the R. L. Polk Company. The choice

of a sampling frame for most large scale national probability surveys is

often one of the major decisions that must be made in carrying out the

survey. Factors such as completeness (e.g., extent to which the frame

coincides with or covers, the target population), availability, ease of

access, cost, type of sampling identifier information contained, currentness, and accuracy of information are some of the typical items which must

be weighed in choosing a frame. A consideration of these factors together

with the major objectives of the survey led to the choice of the Polk files

as the sampling frame for the On-Road Survey. The primary advantages of the

Polk data were: (1) its reasonable availability3 (2) it was a national

file of vehicles, (3) it contained good vehicle identifier information for

stratification of the sample according to desired characteristics, (5) the

fact that vehicle owner name and address were available along with specific

vehicle identifiers, and (6) reasonable cost to access.

The prime contractor for the survey had to enter into a subcontract with the

R. L. Polk Company to furnish a specific sample of vehicles for the survey.

117
The primary disadvantages of the Polk frame were that it excluded

vehicles registered in 14 States,4 or approximately 25 percent of the

vehicle population of interest, and that it would not always provide current

or up-to-date information. This latter problem would arise due to vehicle

resale/owner residence changes as continuous functions over time together

with the elapsed time required for Polk to merge registration files from

individual States into a national file, given that States differ as to the

frequency of updating their own registration files and as to the dates they

provide their respective files to R. L. Polk. This issue of out of date

information was heightened somewhat in implementing the sample for the

On-Road Survey due to a 6 to 8 month period between selection of the sample

from the Polk files and the beginning of actual survey reporting. Some

additional "aging" of the sample, once selected, occurred due to the

implementation of the survey over a 1-year period.

Of the two disadvantages of using the Polk files as the frame,

currentness is judged to be of greater impact since survey experience showed

very little success in following sold vehicles or in following owners who

had moved from their original address (e.g., the one listed on Folk's

4 These States were excluded because the States themselves had placed

restrictions on the use of their vehicle data for surveys such as the

On-Road Survey. Although NHTSA could have pursued release of files for

these 14 States, on an individual appeal basis, such action was not

considered worthwhile in view of the effort required, the potential time

delay in survey implementation that might ensue, and the judgment that

exclusion of the States would, in all likelihood, not cause serious bias.

118
files). Generally this meant that sampled vehicle/owners were not

contacted. Relative to the "excluded States" issue, their omission is not

believed to have significant impact on survey estimates. Table 4-1 lists

the excluded States and Figure 4-1 gives a geographical view of their

distribution, along with those 36 States which were represented in the

survey sample. Since the excluded States are distributed rather evenly

throughout the U.S., and since there is no reason to suspect that the basic

vehicle (year, type, make/model, etc.) distribution differs significantly

between these 14 States and the 36 which were sampled, omission of the 14

States from the sample frame (i.e., a "noncoverage" issue in statistical

sample survey terms) is not believed to constitute a significant concern

insofar as it might cause a bias in the survey estimates.

TABLE 4-1

STATES NOT SURVEYED

(EXCLUDED FROM SAMPLING FRAME)

1. Alaska 8. New Mexico

2. Arkansas 9. Oklahoma

3. Connecticut 10. Pennsylvania

4. Hawaii 11. South Dakota

5. Indiana 12. Virginia

6. Nevada 13. Washington

7. New Jersey 14. Wyoming

These States represent approximately 25 percent of the total U.S. population

of passenger cars and light trucks, per the R. L. Polk Co.

4.1.2 SAMPLE SELECTION, STRATIFICATION, AND DIVISION INTO REPLICATES

Sample sizes were originally derived to provide estimates of

specified precision for the two major vehicle classes (passenger cars and

light trucks) and five model years of interest. The total sample size was

46,000 vehicles—33,500 passenger cars and 12,500 light trucks. Subsequent

119

sample sizes for these 10 vehicle classes, or strata, were altered somewhat

to provide more precise estimates for newer vehicles (e.g., newer model

years were oversampled) keeping the total sample sizes constant at 46,000

total, 33,500 for cars, and 12,500 for trucks.

In order to increase the efficiency of the estimates and to

provide estimates for certain vehicle classes of interest, the vehicle

type/model year strata were further stratified by number of drive wheels

(2-wheel drive, 4-wheei drive) for light trucks, by vehicle size class, and

by type of fuel used, gasoline or diesel. The vehicle size classes

essentially corresponded to those classifications employed, for each model

year, by the Environmental Protection Agency in its laboratory testing of

new vehicles for compliance with Federal emissions standards and for

estimation of vehicle fuel economy or miles per gallon. Within each vehicle

type and year, the sample was allocated proportionately among size classes

except for a few instances where oversampling was employed in order to

obtain reasonable sample sizes for certain rare substrata of interest which

included station wagons, vans, special purpose vehicles, and diesel powered

vehicles.

Tables 4-2 and 4-3 present the allocation scheme of the total

sample among the various strata for passenger cars and trucks, respectively.

In selecting the actual sample of vehicles from the Polk registration files,

one further allocation scheme was employed. The total sample size for each

size class within each higher order stratum was allocated proportionately

among ali the make model combinations shown on the Polk files for that

121
particular size class. This assured representation of each make model on a

basis portional to that make model's representation in the total population

of vehicles in that size class.

The final sample for which data were received and input to the

final data analysis file contained more than 800 different make model

combinations (Examples: 1980 Chevrolet Chevette, 1980 GMC G25 van, 1981

Honda Civic, 1980 Oldsmobile Cutlass Supreme diesel, 1981 Ford Escort, 1979

Ford Bronco 4WD, 1978 Dodge Diplomat, 1977 Toyota Corolla Wagon, etc.)

Prior to implementing the selected sample of 46,000 vehicles, it

was distributed equally among 12 subsamples, or replicates, so that 1/12 of

the total sample could be implemented over each month of a consecutive

12-month period. This step was taken in order to account, or control for,

the seasonal effect on fuel economy. Distribution of the sample was made so

that each vehicle stratum and substratum were equally represented among the

12 replicates.

TABLE 4-2

SAMPLE ALLOCATION SCHEME

Cars and Station Wagons, N = 33,500

STRATUM

Gas

Cars

Station

Diesel

Cars

Station

Total N •

Wagons

Wagons

E

1977

4,100

925

K/A

N/A

5,025

4

1

6

1978

,379

,048

479

124

,030

MODEL

1

4,

1.

6,

979

684

011

845

160

700

YEAR

5

7

1980

,551

713

794

312

,370

6

1

8

1981

,079

,040

931

325

,375

Source: Survey contractor final report, previously cited

122
TABLE 4-3

SAMPLE ALLOCATION SCHEME

Trucks, N • 12,500

STRATUM

Gas

Two-Wheel Drive

Pickups

Vans

Special Purpose

Four-wheel Drive

Pickups

Vans

Special Purpose

Diesel

Two-Wheel Drive

Pickups

Vans

Special Purpose

Four-Wheel Drive

Pickups

Vans

Special Purpose

1977

600

952

21

15

N/A

287

N/A

N/A

N/A

N/A

N/A

N/A

1978

750

824

20

0

N/A

431

225

N/A

N/A

N/A

N/A

N/A

MODEL YEAR

1 979

772

818

17

0

N/A

518

375

N/A

N/A

N/A

N/A

N/A

1980

856

298

28

85

N/A

340

413

N/A

N/A

N/A

N/A

N/A

1981

1,122

399

38

799

N/A

298

469

N/A

N/A

N/A

N/A

N/A

TOTAL 1,875 2,250 2,500 2,750 3,125

Source: Survey contractor Final Report, previously cited.

4.2 QUESTIONNAIRE DESIGN AND DATA COLLECTION METHODOLOGY

As stated earlier, the survey instrument and method of data

collection were based primarily on the results of a NHTSA pilot test. The

survey was conducted by mail. The initial step in the data collection

method was to mail a "prenotification" letter to the owner of each vehicle

123
selected in the sample. Actually, the prenotification mailing contained 2

letters, one from NHTSA, and one from the survey contractor. This was

followed in approximately 2 weeks by the survey questionnaire which was

accompanied by a brief letter of instruction, a small incentive in the form

of a personal fuel mileage booklet, and two decals, one to serve as an

in-vehicle reminder to fill in the log at each fuel purchase, and the second

for use in sealing the completed log for mailing. The log-questionnaire

(see Figure 4-2a) was preprinted with the vehicle make, model, and model

year information: the owner's name, address, and survey identification

number; and, on the opposite side, with address and franking data for

returning the questionnaire (see Figure 4-2b). The questionnaire requested

a few items characterizing the sampled vehicle (Section A) and brief

.information at each fuel purchase during a specified 1-month period (Section

B ). The format of the questionnaire was designed to permit data reduction

of returns via optical scan equipment.

Three-to-four days after the questionnaire was mailed, a reminder

card was sent. A second card was sent shortly before the end of the survey

month as a reminder to send in the log. A second wave of mailings,

exclusive of the prenotification letter were sent to all sampled vehicle

owners who did not respond to the initial wave. Samples of all the

materials used to supplement the survey questionnaire are included in

Appendix B.

The impact on survey response of the prenotification letter, the

personal log-booklet (incentive), and reminder postcards were evaluated in

the NHTSA pilot test, as mentioned before, and each of these items was shown

to have a positive effect on survey response. The use of more valuable gift

124


items or direct monetary payments as further inducements for survey

participation were not considered since these were generally against agency

policy and also since an evaluation of the impact of monetary incentives

used or tested in other surveys did not provide convincing evidence that the

use of such incentives would be at all cost-effective.

Use of the telephone, however, was evaluated as to its effect on

increasing survey response. The original design methodology called for a

telephone followup to a random sample of nonrespondents to the first and

seventh replicates of the main survey. The basic objective of these

telephone followups was to investigate potential nonresponse effects on the

primary variable to be measured in the survey—fuel economy. The plan

called for converting a sufficient number of nonrespondents, through

telephone contact, and persuading them to complete the 1-month fuel-mileage

log. The data on fuel economy thus obtained would then be compared with the

fuel economy data obtained from the main (mail) survey to see if any

significant nonrespondent effect existed.

The results of the telephone followup for Replicate 1 did not

provide sufficient data for making a direct comparison of fuel economy, but

did provide supplementary data from the nonrespondents which was used,

together with other survey return information, to conduct an analysis of

potential nonresponse bias effects on the primary survey objective—the

measurement of on-road fuel economy. Since the telephone followup results

for Replicate 1 did not result in a sufficient number of completed logs the

telephone followup originally planned for Replicate 7 was not performed. The

telephone was further evaluated, however, as to its potential for enhancing

response to the basic mail survey. ' For Replicate 5, instead of sending the

12J.
mail followup wave to all nonrespondents, a portion were contacted via

telephone. Once again, however, use of the phone did not prove significant

in increasing response over that obtained solely from the mail contracts.

One additional significant finding from the telephone followup

experiments was that the rate of vehicle/owner noncontacts was appreciably

higher than that computed merely from mail returns themselves. This

information was used to adjust the survey response/nonresponse rates, which

are discussed in the last section of this chapter.

4.3 DATA COLLECTION, PROCESSING, AND STATISTICAL ESTIMATION

4.3.1 RECEIPT CONTROL

To maintain control over the large volumes of mailings and

receipts in the On-Road Survey, the survey contractor utilized two automated

receipt control files. One file, called the "locator file," was used to

track the location of sampled vehicle owners and the status of their

vehicles. Table 4-4 is a summary of the different designators, or

disposition codes, used to maintain control over the 46,000 vehicles sampled

during the 1-year period of the survey. The second control file used

throughout the survey was to maintain an accounting of the survey

questionnaires, or logs, as to the disposition of each one. Table 4-5

summarizes the codes used by this tracking system.

128

TABLE 4-5

DISPOSITION CODES. FOR RETURNED QUESTIONNAIRES

32 (Second Wave)/42 (First Wave)

Complete (Usable) Log (Section B of log has specified amount

of information)

31 (Second Wave)/41 (First Wave)

Incomplete Log (Vehicle owner attempted to complete the log,

but the information was insufficient)

33 (Second Wave)/43 (First Wave)

Wrong Month (Log filled in for out-of-scope month. Out of

scope falls outsides prior to two months to record-keeping

month, and/or two months after record-keeping month)

38 (Second Wave)/48 (First Wave) .

Inadequate Information (Information not usable because of

format; e.g., owner writes in "10 miles per gallon; what a

lemon1")

Source: Survey contractor final report, previously cited.

4.3.2 DATA PROCESSING

The data reduction and processing function for all returned

questionnaires included a manual review, or edit, keypunching-* the data

reported on the questionnaires, and subjecting the keypunched information to

a machine edit. The manual review served to separate good or complete logs

from incomplete ones and to correct any obvious ambiquities in respondent

reported information.6 Keypunching of questionnaires which passed the

manual edit was performed under subcontract to the survey firm. Data entry

specifications included 100 percent verification of key items such as

odometer reading, fuel amount and certain administrative identification

5 It was not possible to use optical scan equipment, as originally planned, to

capture the data reported on the questionnaires; hence, the questionnaires

were keypunched.

6 The survey contractor final report, previously cited, contains additional

detail on the manual edit of returned questionnaires.

130
items. A periodic random check was made of the keypunched data by the

survey contractor who reported the average error rate at less than one-tenth

of one percent.

The third stage of the data processing function was a machine edit

or "cleaning" program which had as its overall objective the preservation of

a maximum number of completed survey logs subject to certain quality control

specifications. Among the functions carried out by the machine edit are the

following steps:7

(1) verification of individual case/questionnaire identification

number

(2) selection and printing of a random sample of each batch of

keypunched logs for purposes of checking keypunch accuracy

(3) conversion of certain reported data to standard categories

used for processing and data analysis

(4) overriding certain illegal respondent answers with a single

response according to predetermined rules

(5) sorting/merging of survey logs with corresponding data from

the Polk sampling frame data for purposes of inputing

certain information if missing on survey log

Survey contractor report, previously cited.

131
(6) imposing range checks on certain data items:

(a) MPG range for gasoline vehicle: 5-40

MPG range for diesel vehicle: 15-50

(b) Engine displacement: 40-500 cu. in.

(c) Period for which log kept:

waves 1 and 2: _+ 2 mo. from target mo.

wave 3: + 4 10. from target mo.

(wave 3 applies only to Replicates 1 and 5 and

refer to telephone experiments)

(d) Odometer reading: > 1,000 miles

(e) Fuel purchase amount: < 40 gal.

(f) Miles driven between successive log entries: < 500

miles

These ranges provide a check on respondent reported errors

concerning the vehicle, the fuel purchase or odometer (such

as reporting trip odometer readings). The range of months

serves to retain some "early" or "late" logs while still

preserving a general seasonality factor in the data. The

ranges also serve to check on possible omission of fuel

purchase amounts during the recordkeeping period.
(7) to calculate MPG according to an algorithm based on "valid

segments." (see following section on Statistical

Estimation).

(8) to produce an error listing of the data by type of error

(e.g., suspected trip odometer, out-of-range date,

backwards odometer, invalid fuel type, etc.

4.3.3 STATISTICAL ESTIMATION

In order to have reliable estimates of fuel economy, a method of

computation was developed by the sample survey contractor which computes

miles per gallon for each surveyed vehicle based on the concept of "valid

segments." This concept was developed in order to salvage as much data as

possible from each survey log, considering that respondents might

occasionally fail to complete each line of Section B of the log correctly at

each and every fuel purchase during the survey period (e.g., a fuel purchase

might be omitted, numbers transposed/recorded incorrectly, etc.).

133-
A valid segment is defined as the minimum distance over which fuel

economy estimates can be computed. It consists of a minimum of two rows of

information on fuel purchases, from Section B of the questionnaire, in

ascending order, which satisfy the following criteria**:

(1) valid segments are bounded by fuel purchases amounts

designated as "fillups"

(2) valid segments cannot begin or end with an odometer reading

less than 1,000 miles (such as a. trip odometer reading), an

out-of-range date, a descending odometer reading and/or a

descending date. Rows of data within segments, on the other

hand, may have these problems if they have in-range fuel

amounts, since the number of miles driven comes from the

difference between the two segment boundary odometer readings

and because the total fuel used during the segment is the sum

of fuel purchases during the segment. Valid segments do not

have to begin with an in-range fuel amount, since the fuel

amount recorded at the start of the segment does not

constitute fuel consumed during the segment, but rather

reflects consumption during the prior segment, a period of

driving.

(3) segments must finally pass machine edit specifications in

order to be considered valid. These include a specified

range for computed miles per gallon (see preceding section).

Survey contractor final report, previously cited.
Vehicle estimates of mpg are the averages of the more detailed

segment estimates and both are subjected to the mpg range check described in

the preceding section. The formula for calculating mpg for a given vehicle

is the ratio of the total miles driven for all valid segments to the total

fuel purchased for all valid segments, or,

sample

total miles driven for

all valid segments sample ' • ••""• " ••••• •

vehicle total fuel purchased for

all valid segments

The average mpg for a given stratum (e.g. such as the model

year—vehicle type—fuel type—make model group) is a weighted mean across

all vehicles in that particular stratum or,

Mean mpgstratum i = •>,

D

 wi

where MPG^j is the miles per gallon for vehicle j in stratum i,

and Wj_ is the population based weighting factor given by:

where N^ is the number of vehicles in the population of stratum i and

n^ is the number of sample vehicles in stratum i. The population weights

are the actual counts of U.S. registered vehicles as provided from the

national files of the R. L. Polk Company, as discussed earlier in this

report. Population-based weighting procedures improve the accuracy of

survey estimates by correcting for departures of the sample distribution

from the population distribution by stratum. Such departures arise because

of oversampling, used for certain strata and because of differences across

strata in the response rates.

135
4.4 SURVEY RESPONSE AND NONRESPONSE ISSUES

Of the total sample of 46,000 vehicles (actually 46,001 vehicles

were selected for the On-Road Survey), returned logs were received for

10,871 or 23.6 percent of the original sample. Approximately 9.6 percent of

the returned cases or 1,039 logs were not sufficiently complete to keypunch

(i.e., insufficient lines completed for log section of the questionnaire,

log completed for the wrong vehicle, etc) . Of the remaining 9,832 logs

which were keypunched, 918 or 9.3 percent did not meet the criteria set

forth in the machine edit program, and as described in Section 4.3.3, above.

This left 8,914 cases which met all editing/cleaning criteria and are

included on the final survey analysis file. The following table (Table 4-6)

gives the final breakdown, or disposition of the total sample as reported by

the survey contractor.

TABLE 4-6

FINAL DISPOSITIONS FOR TOTAL SAMPLE

(Based on Mail Returns Only)

Number Number Percent

Fielded Cases (Gross Sample) 46,001

Returned Ineligible s (Out of Scope) 1,921

Net Sample

Completed Cases (Logs passing machine edit)

Completed Cases (Logs failing machine edit)

Completed Cases (Not Keypunched)

Refused

Pursuable

Not-pursuable

Undeliverable

Not Returned

Source: Survey contractor final report, previously cited.

136

e edit)

e edit)

44,080

8,914

918

1,039

600

2,409

3,728

6,592

19,880

100.0%

20.2%

2.1%

2.4%

1.4%

5.5%

8.5%

15.0%

45.1%
In most surveys, the response rate is defined as the ratio of

completed questionnaires to the number of "eligible" units in the total,

fielded sample, or

_ Completed Cases

Respons e rat e = _• ' • • •• y • ._.*• ' •_ • •., ,- •, • • • • • •"

Total Fielded Cases - Ineligible Cases

Ineligible cases, as defined in Table 4-6 are defined as: (1) owner had no

knowledge of vehicle, (2) make, model, model year incorrect, (3) fleet car,®

(4) fuel not measurable, (5) vehicle not driven in assigned month, (6)

vehicle junked or stolen, (7) vehicle repossessed. Furthermore, these

designations of ineligibility are based solely on mail returns. If this

basis is accepted for computing survey response rate, and "completed cases"

are defined as only those passing final machine edit, the response rate for

the On-Road Survey is 20.2 percent, as shown in Table 4-6.

However, the above method of computing survey response is

considered overly conservative in view of additional usable information

obtained in the two telephone experiments mentioned earlier in this chapter,

and also in view of alternate ways to define ineligible cases. In the

On-Road Survey a sizeable proportion of the cases resulted in failure to

locate the sample vehicle, either because the owner had moved (with no

forwarding address), the vehicle had been sold (with new owner address

unavailable), or through other problems such as incorrect information from

the sample frame (vehicle registration files). The category "not-pursuable"

in Table 4-6 includes cases of no forwarding addresses and also cases where

9 The sample was designed to exclude fleet vehicles, as previously stated.

However, a handful of returns were classed as fleet vehicles. These, of

course, were considered extraneous and ineligible for the survey.

137
vehicles were sold to car dealers. It was not possible to follow vehicles

that had been sold to dealers. According to a report of a special task force

authorized by the Council of American Survey Research Organizations (CASRO)

in May 1983, for the expressed purpose of developing standardized

definitions of survey response rates, the above cases of noncontact can be

considered as ineligible. The following quote is taken from the Task

Force's report:

"For mail surveys where the frame is not up to date, nonresponse

may occur because the intended recipient of the questionnaire is

no longer at the given address. These cannot be considered as

non-eligible cases unless definite proof is available through

Post Office returns, through personal visits to the address, or

through information from some other source."

In the On-Road Survey, proof that the intended recipient (owner of

sampled vehicle) was no longer at the given address was available through

Post Office returns. All survey mailings were imprinted with "Address

Correction Requested" to assure more thorough treatment of incorrect

addresses, movers, etc., and to improve identification/disposition of the

implemented sample. Cases of "sold vehicles" (unknown, unfollowable

address) fall into the same category because the "intended recipient" (i.e.,

the current vehicle owner) is not at the address to which the questionnaire

was mailed. Again, there is "proof through survey returns."

138
The second element of information for computing an alternate

survey response rate comes from the two telephone experiments. These

experiments were conducted at two different times during the main survey and

utilized random samples of sample vehicles unaccounted for after both waves

of mailing (first telephone test), and vehicles unaccounted for after the

first wave of mailing (second telephone test). These two telephone efforts

were based on reasonably large sample sizes of 1,000 and 776 vehicles,

respectively, for the first and second experiment. The results of these two

telephone efforts showed that an additional 33 percent of the original

sample fell into the categories of "sold vehicle", "no knowledge of

vehicle", "junked/stolen", etc., - all cases that can be considered as

ineligible according to the CASRO study.10

If the additional information obtained from the telephone tests is

utilized along with the definition of ineligibility as developed by the

CASRO Task Force, the following estimates are obtained for response rates to

the On-Road Survey:

Response Rate

(logs passing machine edit) = 33.7 percent

Response Rate

(all completed logs returned) = 41.1 percent

1 0 It is believed that this finding indicates that many people who had

"unavailable vehicles," for whatever reason, did not make the effort to

convey the vehicle status by mail, whereas, such information was obtained

when these individuals were contacted by phone. It takes extra effort to

reply by mail and, no doubt, many people felt a reply was not necessary

since the requested vehicle would not be available for the survey anyway.

139
It is felt that these rates are a more realistic indication of the

response to the On-Road Survey. Considering the fact that the survey

instrument was a diary-type questionnaire of unusually long duration (one

month), and the fact that the survey was conducted essentially by mail,

these response rates are considered to be quite high indeed, compared to

response rates for typical mail surveys.

4.5 POTENTIAL SOURCES OF ERROR IN THE OR.F.ES. STATISTICS

Sample surveys such as ORFES are subject to various sources of

error which can effect the statistics derived and hence the inferences or

conclusions drawn from the survey. This section discusses some of the more

common sources of error and gives an assessment of each relative to the

ORFES statistics. Two major sources of error exist—those due to sampling,

or sampling error and those due to sources other than sampling, or

nonsampling error.

4.5.1 SAMPLING ERROR

Sampling error arises due to the fact that samples (i.e.,

portions) are drawn from populations, as opposed to the populations being

subjected to complete enumeration. Sampling error is based on the theory of

mathematical probability and specific values for these errors can be

computed from surveys conducted according to probability sampling

procedures. Sampling errors cannot be computed for samples selected

140
according to other methods such as subjective or purposive sampling (i.e.,

quota samples are typically of this type). Sampling errors can assist in

the interpretation of survey statistics, such as means, by providing a

measure of how closely the sample statistic estimates the true population

statistic and with what degree of confidence or assurance. Sampling errors

are included in this report along with the mean-estimates relating to the

two primary population parameters of interest, on-road fuel economy and VMT.

4.5.2 NONSAMPLING ERROR

The second type of error which can occur in surveys consists of

several subcategories, usually referred to as (1) data collection,

(2) noncoverage, and (3) nonresponse.

4.5.2.1 DATA COLLECTION

Data collection errors are those that can occur anywhere in the

actual data collection or data automation process. This includes errors v

made by respondents on the original questionnaire; errors made in the

process of editing, coding, and preparing the data for machine processing;

and errors made in the process of transferring original or intermediate

source document information to a machine readable medium such as card, tape,

or disk. Extensive procedures (described earlier in this chapter) as

applied to large scale surveys were taken to assure the quality of the ORPES

data, including both manual and machine edit, with documented steps and

1A1
definitions, and 100 percent verification of key data items. The keypunch

error rate was less than 1/10 of one percent, based on periodic random

checks of this data automation task by an independent observer.

4.5.2.2 NONCOVERA.GE

Noncoverage refers to the failure to include in the sampling frame

all elements in the target population (i.e., the population or universe

about which inferences are desired based on the sample results).

Approximately 25 percent of the target population of vehicles were excluded

from the ORFES frame due to restrictions imposed by certain of the States on

the use of their vehicle registration files.

Noncoverage effects generally have less effect on sample means

than on simple totals11. In this report, we are concerned exclusively with

mean estimates as opposed to totals. Additionally, weighting of sample data

with population totals, where available, can reduce the effect of

noncoverage. Such population data are often unavailable for large-scale

surveys, but for ORFES, they were available in the form of national vehicle

registration counts and have been used to weight the survey data, as

described at various points throughout the report. Finally, the noncoverage

proportion of approximately 25 percent could introduce a bias if there were

reason to believe that the vehicles in the 14 restricted States differed

significantly, or were driven differently, or in an environment different

from those vehicles in the 36 included States. Since the 14 States were

rather evenly distributed, geographically, there is little reason to suspect

11 "Survey Sampling", Leslie Kish, John Wiley and Sons, Inc., Copyright 1965.

1*2
that these States represent a general driving/vehicle usage environment

different from the 36 states comprising the sampling frame. Neither is

there reason to suspect that the vehicle population itself (i.e., the

distribution of vehicles by type, size class, engine size, etc.) in the

restricted States is significantly different from the vehicle population in

the surveyed States. Even if slight differences did exist in these vehicle

characteristics, they would be compensated for by the inclusion of the

population weights in the formulae used for computing the various

statistical estimates.-

4.5.2.3 NONRESPONSE EFFECTS

Nonresponse effects in surveys can arise if the characteristics of

the target population being sampled differ between that group which reports

in the sample (respondents) and that group for which no reports are received

(nonrespondents). Statistically the nonresponse effect can be shown to be

proportional to the magnitude of the nonresponse and the magnitude of the

difference between the means of the characteristic being measured in the two

groups. Symbolically, this can be represented by:

RB (X, ) = P2

 U i " X2 ?

12 "Kish", Op. Cit.

143
where PB (Xi) denotes the relative bias in the mean estimate (X^ )

as fuel economy; P2 is the proportion of nonrespondents in the original

sample; X2 is the mean estimate for the nonrespondent group; and X is the

true, or overall population mean. In order for the nonresponse bias to be

important, the above equation implies that a large nonresponse must be

accompanied by a large difference between the two subpopulation means.

In order to gain insight into whether nonresponse may induce bias

into survey statistics, some method to obtain this information on the

nonrespondents must be developed. Two ways of estimating the effect of

nonresponse are to: (1) obtain additional information, preferably on the

direct variable of interest, via intensive followup with a subsample of the

nonrespondents; or (2) use other, a priori information or analysis. In

ORFES which was conducted basically by mail, telephone followup tasks were

an integral part of the original survey design in order to seek such

nonresponse information. Unfortunately, while the telephone followup did

provide information to better define sample disposition and

response/nonresponse rates, and on vehicle and driver characteristics (see

Section 4.4), an insufficient number of nonrespondents were converted to

provide a reliable estimate of fuel economy for that group.

As an alternate method of estimating any nonresponse effect, an

analysis was performed which evaluated certain vehicle and driver

characteristics between the respondent and nonrespondent group as to their

possible effect on the mean variable of interest, fuel economy. A first

part of this analysis looked at differences between responders and

nonresponders for vehicle factors known to be associated with fuel economy

HA
(i.e., engine size, transmission, presence of air conditioning, etc.).

Also, differences in response rates were evaluated for other vehicle factors

such as size class, type of fuel, and number of drive wheels (trucks).

Overall, few differences of a practical nature were noted for these vehicle

factors between the respondents and nonrespondents. Furthermore, even where

certain' small, statistically significant differences were found, these

should be compensated for by the population weighting scheme employed (i.e.,

actual population counts by size class, type of fuel, and make model which

should also be highly correlated with finer vehicle characteristics such as

engine size, transmission type, etc.)

The analysis of driver related factors between the respondent and

nonrespondent groups covered five additional items obtained on the original

questionnaire or in the telephone followup. These were:

(1) Tune-up in last 3 months? (Yes/No)

(2) Wheel alignment in last 3 months? (Yes/No)

(3) Tire pressure check in last 3 months? (Yes/No)

(4) Proportion of city-highway driving

(5) Heavy usage? (off-road, snow, etc.) (Yes/No)

Only one of the five factors, tire pressure check, was found to be

significantly different between respondents and nonrespondents.

Seventy-three percent of nonrespondents reported a pressure check within the

last 3 months compared to 85 percent for the respondent group. Although

this difference was statistically significant, the small relative magnitude

145
of the difference together with the small fuel economy effect expected due

to more frequent tire pressure checks imply that the difference is not of

practical significance.

The overall finding from the nonrespohse analysis was that the

effect of any bias on the estimates of on-road fuel economy appeared small.

Although the nonresponse portion of the sample was near 60 percent, little

evidence was found to indicate that the mean fuel economy differed between

the respondent and nonrespondent groups. If any bias did exist, it would

likely be positive (i.e., survey estimates would tend to overstate slightly,

true on-road fuel economy). Based on an examination of all information

available, any bias effect due to nonresponse in the survey is believed to

be negligible.

Since the original primary objective of the survey was to estimate

on-road fuel economy, the nonresponse analysis was focused on this

parameter. No separate analyses were attempted with respect to VMT.

Considering the two components of nonresponse bias discussed above, the

primary concern relative to possible bias in VMT centers on the question,

"Is there reason to suspect that nonrespondent vehicles tend to have higher

or lower VMT than respondent vehicles?"

To the extent that vehicle characteristics such as size class,

fuel type, etc., are related to VMT, these have essentially been taken care

of in the sample stratifications and allocations and in the weighting of the

statistical estimates. To the extent that any of the driver characteristics

discussed above (tune-up frequency, frequency of checking tire measure,

proportion city versus highway driving, etc.) are related to VMT, there was

146
little difference found for these factors between the respondent group and

the nonrespondent group. The sample, being nationally representative, gave

equal probability of selection of all vehicles, be they low VMT, high VMT,

or whatever characteristics they possessed.

Perhaps the issue can only be evaluated further on a subjective or

speculative basis. It is possible to postulate that high mileage drivers

might be less apt to participate in a survey such as ORFES due to the

time/effort required to complete the log since these drivers would be more

occupied with the driving task and other purposes relative to their reasons

for driving.13 on the other hand, it is possible to speculate that those who

drive very little (such as elderly drivers) would be less apt to participate

in ORFES since the primary objective was to measure fuel economy and such

drivers could assume that their experience would not be sufficient to give a

reliable estimate of mpg.

From the standpoint of estimates of VMT from prior surveys and

studies, which are characteristically higher than the ORFES estimates (see

Chapter 3.0), greater interest would lie in showing whether there might be a

low bias. However, from an objective standpoint, the possibility of a bias

in the other (high) direction must be given equal emphasis. In summary, at

this juncture at least, no plausible argument is apparent that could

indicate a nonresponse bias in the VMT estimates, either low or high.

1 3 To the extent that "high mileage" could be associated with "vacation period

driving", one might look for lower response rates in the summer months

relative to the other months. Response rates for these months did not

evidence any unusual patterns in ORFES.

147
CHAPTER 5

PRINCIPAL SURVEY FINDINGS AND RESULTS

This Chapter summarizes the primary findings and results of the On-Road

Fuel Economy Survey. These findings are based on analyses of the data

collected in the survey as it relates to two primary topics: (1) the actual

fuel economy achieved in normal, everyday driving by the Nation's late model

vehicle owners, and (2) the average annual vehicles miles traveled by age of

the vehicle. The findings are presented under the following subtopics: (1)

on-road fuel economy for passenger cars, (2) on-road fuel economy for light

trucks, (3) comparison of on-road fuel economy with corporate average fuel

economy, (4) comparison of on-road fuel economy with Federal standards, (5)

estimated reduction in energy consumption and equivalent dollar value of

more fuel-efficient vehicles, and (6) annual vehicle miles traveled-.

5.1 ON-ROAD FUEL ECONOMY RESULTS - PASSENGER CARS

(1) During the first 4 years of the Federal fuel economy

regulations (i.e., Model Years 1978 through 1981), the on-road fuel economy

of the U.S. passenger car fleet increased by 41 percent compared to the fuel

economy of the 1977 Model Year fleet, the year immediately prior to

commencement of the regulations.^ In terms of miles per gallon (mpg), the

fleet average rose from 15.2 in 1977 to 21.4 in 1981.

As stated previously in this study, fuel economy increases may result from

market forces as well as from CAFE standards.

148
(2) The greater portion of this gain in fuel economy is

attributed to the domestic fleet (e.g., vehicles manufactured by domestic

manufacturers) which saw its national average mpg climb from 14.5 in 1977 to

20.2 in 1981, a gain of 39 percent. That portion of the U.S. passenger car

fleet comprised of import vehicles experienced an increase from 23.7 mpg to

26.7 mpg, or about 13 percent. (It should be noted that the domestic

passenger car fleet was originally composed of predominately larger

vehicles, relative to the import fleet, and therefore the incentive to

Improve fuel efficiency was much greater on the part of domestic

manufacturers than foreign manufacturers).

(3) Fuel economy gains of 25 percent to 40 percent were noted for

most size classes of passenger cars, with the highest gain for compacts at

almost 80 percent and the lowest gain for the mini class at only 6.5

percent.

(4) Among domestic manufacturers, fuel economy gains over the

4-year period ranged from a low of 25 percent for American Motors to a high

of 70 percent for Chrysler which in the last year (1980-1981) showed a much

larger than average jump of nearly 6 mpg.

(5) Among foreign manufacturers, fuel economy gains were modest

except for a 30 percent increase (1977 to 1981) for Volkswagen resulting

from a large penetration of diesel sales in the 1979-1981 period.

149
5.2 ON-ROAD FUEL ECONOMY RESULTS - LIGHT TRUCKS

(1) During the 3-year period from 1978 to 1981, the on-road fuel

economy for the U.S. fleet of 2-wheel drive light trucks increased by 26

percent (from 13.A mpg to 16.9 mpg). The fuel economy for 4-wheel drive

light trucks increased by slightly less, 17 percent (from 12.3 mpg to 14.4

mpg). Fuel economy improvements for light trucks, measured by percentage

improvement, were less than those for passenger cars.2

(2) As was the case for passenger cars, greater fuel economy

improvement was made for domestic light trucks than for import light trucks.

The relative increases for the two groups were:

2-wheel drive

domestic trucks, +21% mpg

import trucks, +9% mpg

4-wheel drive

domestic trucks, +9% mpg

import trucks, +4% mpg3

Again, as was true for passenger cars, the domestic light truck fleet was

composed of mainly larger vehicles than the import fleet and hence the

greater incentive for domestic manufacturers to increase mpg.

^ As stated previously in this study, fuel economy increases may result from

market prices as well as from CAFE standards.

3 1980 to 1981 increase only.

150
5.3 ON-ROAO FUEL ECONOMY COMPARED TO CAFE4

(1) On-road fuel economy consistently fell below corresponding

corporate average fuel economy (CAFE) levels for the 4 model years of

vehicles studied in the survey. For passenger cars, this difference

remained essentially constant with on-road mpg being approximately 15

percent below the respective CAFE level for each year. For 2-wheel drive

light trucks, the- EPA to on-road difference was slightly greater than for

cars at an average of about 16 percent per year, and, there was also some

indication that this difference could be increasing with the 1981 vehicles

showing a difference greater than 18 percent.

That laboratory testing overstates actual, on-road fuel economy

has been known for several years. However, some prior studies have indicated that this difference was increasing whereas other studies have

indicated a decrease in this difference for passenger cars. This study

shows no trend in either direction, but rather that the difference has

remained essentially constant, particularly since 1979.

(2) For 4-wheel drive trucks, on-road difference relative to CAFE

was highest of all vehicle classes, averaging nearly 20 percent for the

period 1979-1981 with the difference being nearly 23 percent for 1981.

4 Recent rulemaking action (50 FR 27172, July 1, 1985) by the EPA, adjusted

upward the EPA CAFE values used in this study for Model Year 1980 and 1981

due to test procedure changes. While this information was not available at

the time this study was written, thee effect of this EPA revision is to

increase somewhat, the amounts of the EPA CAFE to on-road differences for

Model Years' 1980 and 1981, as found in this study.

151
(3) Except for 4-wheel drive trucks, domestic vehicles showed

somewhat greater CAFE to on-road difference than did import vehicles.

(4) Among domestic manufacturers of passenger cars, the difference

between CAFE and on-road experience was reasonably consistent with Chrysler

and AMC showing slightly less difference than Ford and GM.

(5) For import passenger cars, the greatest CAFE to on-road

decrease was noted for the captive imports of Ford and Chrysler. Among the

6 foreign manufacturers represented in the survey, Volkswagen was the only

one whose on-road mpg consistently (i.e., for all model years) equalled or

exceeded its respective CAFE numbers. Although not specifically

investigated in this study, one reason for Volkswagen's equaling or

exceeding CAFE levels is believed to be its large proportion of

diesel-powered vehicles for the years studied together with'the finding that

diesel-powered vehicles exhibit less mpg difference, laboratory tests versus

on-road, than conventional gasoline fueled vehicles.

5.4 ON-ROAD FUEL ECONOMY COMPARED TO FEDERAL STANDARDS

(1) For all 3 categories of vehicles, passenger cars, 2-wheel

drive light trucks, and 4-wheel drive light trucks, the on-road fuel economy

ranges from 8-9 percent below the Federal standard levels for Model Years

1978-1979; for 1980-1981, on-road mpg is much closer to the standard levels.

Although the differences are small, on-road mpg is above the standard

levels in several instances.

152
(2) A comparison of domestic and import manufacturers shows that

domestic vehicles are below the Federal standard levels by about 10 percent

for each model year while import vehicles considerably exceed the standard

levels with the on-road mpg ranging from 20 percent to 45 percent above the

respective standard. As has been noted previously, the fuel economy of the

import fleet, being composed of small vehicles, was not only considerably

higher than the fuel economy of the larger and heavier domestic fleet, prior

to enactment by the first Federal standards, but in most cases, exceeded the

standard levels, even as late as 1981.

5.5 ESTIMATED REDUCTION IN ENERGY CONSUMPTION AND EQUIVALENT DOLLAR

VALUE OF MORE FUEL-EFFICIENT VEHICLES

(1) Based on the actual fuel economy as estimated from the On-Road

Fuel Economy Survey and compared with the fleet of Model Year 1977 vehicles,

it is estimated that the total U.S. fleet of passenger cars and light trucks

manufactured from the beginning of the Federal Fuel Economy Standards

through Model Year 1981 will consume a total of 45.6 billion gallons (1

billion, 86 million barrels) less fuel over their expected lifespan. This

is equivalent to 974 fewer gallons per each vehicle. These energy

reductions translate to a dollar value, in 1984 dollars, of $53.8 billion

total, or $1,146 per vehicle.

5.6 ESTIMATES OF VEHICLE MILES TRAVELED

An analysis of vehicle odometer readings for the approximately

9,000 vehicles reporting in the On-Road Survey resulted in the following

findings concerning vehicle miles of travel:

153
(1) The average annual miles traveled, per vehicle, is essentially

the same for both passenger cars and light trucks—about 6,000 miles per

year. This finding is believed to indicate that the usage environments

(length of trip, trip purpose, etc.) are similar for cars and light trucks.

(2) Average annual miles traveled shows little practical variation

among size classes of vehicles for both cars and trucks, or between 2-wheel

drive and 4-wheel drive light trucks.

(3) Average annual miles per vehicle shows a distinct decline with

vehicle age. In the first year of vehicle life, average miles traveled is

estimated at 14,000. However, by the 5th year by age, average travel per

vehicle drops to 6,500 miles, or less than half the travel during the first

year. The data strongly indicate that this declining trend of travel with

vehicle age continues throughout the life of the vehicle.

(4) Vehicle travel was found to be considerably higher for diesel

vehicles than for vehicles powered by conventional gasoline engines. This

difference was larger for passenger cars than for light trucks.

Additionally and in contrast to the finding for the overall fleet, vehicle

size appeared to be a significant factor as well, with small diesel vehicles

showing a greater increase in miles driven over their gasoline counterparts,

than large diesel vehicles.

Although other factors may be involved, it is believed that the

most likely reason behind the greater travel by diesel vehicles is the lower

fuel cost per mile for diesel vehicles over gasoline-powered vehicles.

154
(5) The findings for average annual vehicle travel from the

On-Road Fuel Economy Survey are in general agreement with those of most

earlier travel surveys for the first few years of a vehicle's life.

However, beginning with the 5th to 6th years of vehicle life, the On-Road

Survey shows a markedly greater rate of decline in average annual travel

than all earlier known surveys.

(6) Average annual travel per vehicle, both passenger cars and

light trucks, for all age vehicles (e.g., for the total U.S. fleet of cars

and light trucks) on the road is estimated at 6,025 miles. This contrasts

with estimates of 9,000 to 11,000 miles based on other known travel surveys

or studies.

(7) The implications of the findings on vehicle miles of travel

from the On-Road Survey are that both per vehicle and total'(all vehicles)

annual miles traveled for passenger cars and light trucks are substantially

lower than heretofore generally believed, based on prior known travel

surveys, or on other estimates of vehicle miles of travel. Fleet vehicles

were not included in the survey. However, travel by fleet vehicles does not

appear to be of sufficient magnitude to account for the lower VMT findings

found in this study.

(8) While average and total annual travel per vehicle is lower

than most prior studies have found, the variation travel among vehicles of

the same age is very large indeed. For example, for 1977 vehicles, which

had been driven an average of 59,000 miles at the time of the survey, it is

estimated that in the total population of 1977 models, the total, per

155
vehicle mileage could range as low as 10,000 or as high as 107,000! Other

model year vehicles showed similar large variations in mileage. This is

believed to primarily reflect the vehicle owner/usage characteristics. A

few owners (such as certain elderly persons,for example) may drive only a

few hundred miles per year. On the other hand, certain persons, due to the

occupation, avocation, etc., may drive tens of thousands of miles per year.

156
REFERENCES

(1) "Annual Energy Outlook, 1984," Energy Information Administration,

U.S. Department of Energy, DOE/EIA-0383 (84), January 1985.

(2) Atkinson, Jean, et. al. "On-tne-Road Fuel Economy Survey, Final Data

Collection Report," NORC, Chicago, IL, October 1984.

(3) Automotive Fuel Economy Program, Seventh Annual Report to Congress,"

U.S. Department of Transportation, National Highway Traffic Safety

Administration, January 1983.

(4) Automotive News, 1976-1978 (various weekly publications).

(5) Census (1972) of Transportation, Vol. II, Truck Inventory and Use

Survey, U.S. Department of Commerce, March 1974.

(6) Draft Notice of Proposed Rulemaking, Fuel Economy of Motor Vehicles,

Revisions to Improve Fuel Economy Labeling and the Fuel Economy Data

Base," 40 CFR Part 600, Environmental Protection Agency, March 1980.

(7) Duncan, Acheson J. "Quality Control and Industrial Statistics,"

Revised Edition, 1959, Richard D. Irwin, Inc.

(8) Economic Report of the President, Transmitted to the Congress,

February 1985.

(9) "Energy Projections to the Year 2010, A Technical Report in Support of

the National Energy Policy Plan," draft report, U.S. Department of

Energy, April 2, 1985.

(10) Ezekiel, M., and Fox, K.A. "Methods of Correlation and Regression

Analysis," Third Edition, Copyright 1959, John Wiley and Sons, Inc.

(11) "Gas Mileage Guide," Environmental Protection Agency, Years

1977-1981.

(12) Hald, A. "Statistical Theory with Engineering Applications,"

Copyright 1952, John Wiley and Sons, Inc.

(13) "Highway Statistics," 1983, Federal Highway Administration, U.S.

Department of Transportation.

(14) Hu, Patricia. "Scrappage Rates of Passenger Cars and Trucks in

1970-1982," Transportation Energy Group, Oak Ridge National

Laboratory, August 10, 1983.

(15) "Improving Energy Efficiency," Title V, Motor Vehicle Information and

Cost Savings Act (15 U.S.C. 1901 et seq.)

(16) Kish, Leslie. "Survey Sampling," Copyright 1965, John Wiley and Sons,

Inc.

157
(17) Kuzmyak, J.R. COMSIS Corp., "1977 National Personal Transportation

Study, Report No. 5: Household Vehicle Utilization, U.S. Department

of Transportation, Federal Highway Administration, April 1981.

(18) "Lifestyles and Household Energy Data," Washington Center for

Metropolitan Studies, 1977.

(19) "Light Truck Fuel Economy Standards for 1985," U.S. Department of

Transportation, National Highway Traffic Safety Administration, 49 FR

41250, October 1984.

(20) McNutt, B. D. and Pirkey. U.S. Department of Energy; Dulla, R. and

Miller C. Energy and Environmental Analysis, Inc., "A Comparison of

Fuel Economy Results from EPA Tests and Actual In-Use Experience,

1974-1977 Model Year Cars," February 1978.

(21) McNutt, B. D., U.S. Department of Energy; Dulla R., Energy and

Environmental Analysis, Inc. "On-Road Fuel Economy Trends and

Impacts," February 1979.

(22) McNutt, B. D. "Statement of B. D. McNutt, Senior Technical Advisor,

Office of Conservation Policy and Evaluation, U.S. Department of

Energy, before the Sub-Committee on Environment, Energy, and Natural

' Resources of the Committee on Government Operations,"

January 29, 1980.

(23) McNutt, B. D., U.S. Department of Energy; Dulla, R. and Crawford, R.,

Energy and Environmental Analysts, Inc.; McAdams, H.T., Falcon

Research and Development Company. "Comparison of EPA and On-Road Fuel

Economy for 1975-1980 Cars," (from copies of slides from presentation

at Society of Automotive Engineers).

(24) McNutt, B. D. U.S. Department of Energy, "Comparison of Gasoline and

Diesel Automotive Fuel Economy as Seen by the Consumer," paper for SAE

Annual Meeting, December 1980.

(25) Murrell, D. (principal author). Environmental Protection Agency,

"Passenger Car Fuel Economy: EPA and Road, A Report to the Congress,"

in Response to the National Energy Conservation Policy Act of 1978,

Public Law 95-619, Title IV, Part I, Section 404.

(26) "National Travel Survey 197B," Cambridge Systematics, Inc., magnetic

tape prepared by the National Science Foundation, 1979.

(27) "Nationwide Personal Transportation Study: Annual Miles of Automobile

Travel, Report No. 2," Federal Highway Administration, U.S. Department

of Transportation, April 1972.

(28) "National Vehicle Population Profile, Passenger Cars, Light Trucks,"

R. L. Polk Co., July 1, 1982.

(29) OMB Circular No. A-94, March 27, 1972.

(30) "Projection of Light Truck Population to Year 2025," Oak Ridge

National Laboratory, ORNL/Sub-78/14285/1 Special, October 1978.

158
(31) "Regulatory Reform - The Review Process," U.S. Department of

Transportation, National Highway Traffic Safety Administration, March

1982, (D0T-HS-B06-159).

(32) "Residential Energy Consumption Survey," Energy Information

Administration, Office of Energy Markets and End Use, U.S. Department

of Energy, (various documents).

(33) Schneider, et. al. General Motors Corporation, "In-Use Fuel Economy

of 1980 Passenger Cars," SAE Paper No. 810384, February 23-27, 1981

(meeting).

(34) Shonka, D. B., "Characteristics of Automotive Fleets in the United

States, 1966-1977," Oak Ridge National Laboratory, ORNL/TM-6449

Special, September 1978.

(35) South, Neil. "1978 to 1980 Ford On-Road Fuel Economy," draft of SAE

Paper No, 810383'for presentation at 1981 SAE International Congress

and Exposition on February 26, 1981.

(36) "The Fuel Consumption Survey," Statistics Canada, Special Surveys

Division, 3C-3 Jean Talon Bldg., Ottawa, Ontario (various documents).

(37) The U.S. Automobile Industry, 1983 - Report to the Congress from the

Secretary of Commerce, December 1984.

(38) Thornton, J. National Highway Traffic Safety Administration, "The Use

of Weighted Vehicle Miles Traveled in Estimates of Corporate Average

Fuel Economy," Internal Report, NHTSA, July 1981.

(39) "Transportation Energy Data Book," Sixth Edition, U.S. Department of

Energy.

(40) "Transportation Energy Data Book," Edition 7, Oak Ridge National

Laboratory, ORNL-6050, June 1984.

(41) Ward's Automotive Year Book, 1978 through 1982 edition.

159
APPENDIX A 

LISTING OF VEHICLE MAKE MODELS 

 (I.E., SUBSTRATA) 

SAMPLED IN ORFES 

160 
ALL

cr>

STRATA

MINI

SUB-COMPACT

TftBtfi 3

AM) K m

CAHYEAR. 1977

ICAR MAKE AND MODEL

CHEVROLET CORVETTE (2-SEATER)

OATSUN B-210

DATSUN 28OZ (2-SEATER)

DODGE COLT

HONDA CIVIC

HONDA CIVIC CVCC

PLYMOUTH ARROW

TOYOTA CELICA

VOLKSWAGON BEETLE

3|

AMC GREMLIN

BUICK SKYHAWK

CHEVROLET CAMARO

CHEVROLET CHEVETTE

CHEVROLET VEGA

OATSUN F-1O

DATSUN 81O

FORO MAVERICK

FORD MUSTANG II

FORD PINTO

HONDA ACCORD CVCC

LINCOLN-MERCURY BOBCAT

LINCOLN-MERCURY COMET

PONTIAC FIREBIRD

1

1

1

1

1

1

1

1

I

1

1

1

1

1

3|

3|

1O|

<H

1|

1|

Hi

61

7|

9

3

1

4
•OSOE 3

MAKE AID MODEL

CAKfERRs 1977

ALL

t-Z

STRATA

SUB-COMPACT

COMPACT

MIDSIZE

CAR MAKE AND MODEL

PONTIAC SUNBIRO

TOYOTA COROLLA

TOYOTA CORONA

VOLKSWAGON DASHER

VOLKSWAGON RABBIT

VOLKSWAGON SCtROCCO

BUICK SKYLARK

CADILLAC SEVILLE

CHEVROLET MONTE CARLti

CHEVROLET NOVA

DODGE ASPEN

FORO GRANADA

FCfeO THUNDCRBIRO

LtNGOLN-MERCUdY MONARCH

LINCOLN-MERCURY VERSAILLES

OLDSMOBILE OMEGA

PLYMOUTH VOLARE

PONTIAC GRAND PRIX

PONTIAC VENTURA

BUICK CENTURY

BUICK REGAL

CADILLAC ELDORADO

CHEVROLET MALIBU

N 1

3|

1i|

2\

2|

u|

'I

• 1

261

«*!

U.~ - H

1 '{

12|

17]

1 s|

B|

i|

1 "1

(CONTINUED)
TP8LE 3

MAKE MOHXIEZ.

CMWEAR= 1977

ALL

STRATA

MIDSIZE

LARGE

CAR MAKE AND MODEL

CHRYSLER CORDOBA

CHRYSLER LEBARON

DODGE CHARGER SE

FORD LTO II

LINCOLN-MERCURY CONTINENTAL

MARK V

LINCOLN-MERCURY COUGAR

LINCOLN-MERCURY COUGAR XR-7

OLDSMOBILE CUTLASS

OLDSMOBILE CUTLASS SUPREME

PLYMOUTH FURY

PONTIAC LEMANS

DODGE DIPLOMAT

AMC MATADOR

BUICK ELECTRA

BUICK LESABRE

CADILLAC DEVILLE

CHEVROLET CAPRICE

CHEVROLET IMPALA

CHRYSLER NEWPORT

CHRYSLER NEW YORKER

DODGE ROYAL MONACO

FORD LTD

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

Ml

3|

3|

101

,|

4|

4|

•1

281

4|

•1

2|

H |

321

261

a|

4|

341

(CONTINUED)
TWOJE 3

H

1977

ALL

STRATA

LARGE

SMALL STN WAGON

MIDSIZE WAGON

CAR MAKE AND MODEL

LINCOLN-MERCURY LINCOLN

CONTINENTAL

LINCOLN-MERCURY MERCURY

MARQUIS

OLDSMOBILE DELTA 88

N I

6

11

8|

OLDSMOBILE 98 | 1i|

PLYMOUTH GRAN FURY | i|

PONTIAC BONNEVILLE 12|

PONTIAC CATALINA | 5|

AMC HORNET WAGON

AMC PACER WAGON

OATSUN F-1O WAGON

DATSUN 81O WAGON

FORO PINTO WAGON

HONDA CIVIC CVCC WAGON

PONTIAC ASTRE SAFARI WAGON

TOYOTA COROLLA WAGON

TOYOTA CORONA WAGON

VOLKSWAGON DASHER WAGON

BUICK CENTURY WAGON

CHEVROLET MALIBU WAGON

4|

4

1|

5|

i *9|

; 5|

•I

!

 6I

j '•

4|

4|

161

DODGE ASPEN WAGON | 29|

DODGE MONACO WAGON

FORD LTO It WAGON

4|

1|

(CONTtNUED)
TRBt£ 3

CE *N0 H t

CRKVEAft* 1977

ALL

STRATA |CAR MAKE AND MODEL

MIDSIZE WAGON

LARGE WAGON

OLDSMOBILE VISTA CRUISER WAGON

PLYMOUTH FURY WAGON

PLYMOUTH VOLARE WAGON

PONTIAC LEMANS SAFARI WAGON

AMC MATADOR WAGON

BUICK ESTATE WAGON

CHEVROLET CAPRICE WAGON

CHEVROLET IMPALA WAGON

CHRYSLER TOWN & COUNTRY WAGON

LINCOLN-MERCURY MARQUIS WAGON

OLDSMOBILE CUSTOM CRUISER

WAGON

PLYMOUTH GRAN FURY SUBURBAN

WAGON

PONTIAC SAFARI WAGON

SUBCOMPACT DIES |VOLKSWAGON RABBIT

SMALL PICKUP-GAS

STD PICKUP-GAS

N

8

2|

1 361

5|

4

n

9|

121

2|

4|

«l

1

6

«l

CHEVROLET LUV PICKUP | J|

DATSUN PICKUP

FORD COURIER PICKUP

TOYOTA HILUX PICKUP

CHEVROLET C-1O PICKUP

Hi

1|

5|

15|

CHEVROLET C-2O PICKUP | 5|

CHEVROLET EL CAMINO | 4|

DODGE D-1OO PICKUP | 4|

(CONTINUED)
ALL

o»

STRATA

STO PICKUP-GAS

VAN-GAS

SPECIAL USE-GAS

STO PICKUP 4W0

SPECIAL USE 4W0

TABt£ 3

MPXE N O MODEL

1977

(CAR MAKE AND MODEL

DODGE D-2OO PICKUP

FORD F-15O PICKUP

FORO F-JOO PICKUP

FORO RANCHERO

CHEVROLET SPORTVAN

CHEVROLET UTILITY VAN

DODGE SPORTSMAN

DODGE UTILITY VAN

FORD ECONOLINE VAN

FORD CLUB WAGON VAN

GMC RALLVE WAGON

PLYMOUTH VOYAGER VAN

VOLKSWAGON BUS

GMC SUBURBAN

CHEVROLET SUBURBAN

DODGE RAMCHARGER

|GMC JIMMY

|JEEP PICKUP 25

--• •

2|

" I

.--4.

33|

n

3|

•I

-4-

t|

H

DODGE RAMCHARGER

GMC JIMMY

CHEVROLET BLAZER

FORO BRONCO

JEEP CHEROKEE

1

1

1

1

1

2|

2|

13|

9|

3|

(CONTINUED)
ALL

TABU; 3

MAKE AM) KXEL

CW«EM*= 1977

N I

STRATA

SPECIAL USE 4HD

|CAR MAKE AND MODEL

«._----—•___»_ - .

JEEP CJ-5

JEEP CJ-7

JEEP WAGONEER

PLVMOUTH TRAILOUSTER

41

— • -

3|
Alt) MQCEL

CMHEAR= 1978

ALL

STRATA

MINI

00

|CAR MAKE AND MODEL

CHEVROLET CORVETTE (2-SEATER)

OATSUN B-210

OATSUN 280Z (2-SEATER)

DODGE CHALLENGER

DODGE COLT

FORO MUSTANG II

FORD PINTO

HONDA CIVIC

LINCOLN-MERCURY BOBCAT

PLYMOUTH ARROW

31

" I

.--•

2|

.-._•

3|

6|

--*

6|

--•

--•

2|

.-•

3|

«•

H

--•

31

— •

'I

SUB-COMPACT AMC GREMLIN

BUtCK OPEL

CHEVROLET CAMARO

CHEVROLET CHEVETTE

CHEVROLET MONZA

OATSUN F-1O

DATSUN 51O

FORO FIESTA

HONDA CIVIC CVCC

HONDA ACCORD

OLOSMOBILE STARFIRE

PONTIAC FIREBIRD

PONTIAC SUNBIRO

22|

---•

-I

Hi

«l

--•

' I

—-•

H
TM02 3

MAKE AND MODEL

C 1978

ALL

STRATA

SUB-COMPACT

COMPACT

MIDSIZE

CAR MAKE AND MODEL

TOYOTA CELICA

TOYOTA COROLLA

TOYOTA CORONA

VOLKSWAGON DASHER

VOLKSWAGON RABBIT

VOLKSWAGON SCIROCCO

DODGE OMNI

PLYMOUTH HORIZON

AMC CONCORD

AMC PACER

BUICK SKYLARK

CAOILLAC SEVILLE

CHEVROLET NOVA

DODGE ASPEN

FORD GRANADA

LINCOLN-MERCURY MONARCH

LINCOLN-MERCURY VERSAILLES

OLDSMOBILE OMEGA

PLYMOUTH VOLARE

PONTIAC PHOENIX

AMC MATADOR COUPE

BUICK CENTURY

BUICK REGAL

N

11

3|

3|

ia|

3|

6|

14|

5|

1 H

3|

1 22|

15|

1 2O|

i n

1 21

1 61

1 13|

I *l

I H

ao|

(CONTINUED)
TAHl£ 3

MAKE MB MODEL

CUOEAR* 1978

ALL

STRATA

MIDSIZE

LARGE

CAR MAKE AND MODEL

CHEVROLET MALIBU

CHEVROLET MONTE CARLO

CHRYSLER CORDOBA

CHRYSLER LEBARON

CHRYSLER MAGNUM $E (DODGE)

DODGE DIPLOMAT

DODGE MONACO

FORD FAIRMONT

FORD LTD II

FORD THUNDERBIRD

LINCOLN-MERCURY CONTINENTAL

MARK V

LINCOLN-MERCURY COUGAR

LINCOLN-MERCURY COUGAR XR-7

LINCOLN-MERCURY ZEPHYR

OLOSMOBILE CUTLASS

OLDSMOBILE CUTLASS CALAIS

OLOSMOBILE CUTLASS SUPREME

PLYMOUTH FURY

PONTIAC GRAND PRIX

PONTIAC LEMANS

BUICK ELECTRA

BU1CK LESABRE

1

1

I

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

M I

26

251

el

"1

s|

2|

251

6|

21|

3

3|

12|

111

3|

291

H

151

12|

•1

23|

(CONTINUED)
TABU 3

MKKE M O MODEL

CAK¥EAR» 1978

• L I

STRATA ICAR MAKE AND MODEL

LARGE

SMALL STN WAGON

BU1CK RIVIERA

CAOILLAC DEVILLE

CADILLAC FLEETWODO

CHEVROLET CAPRICE

N I

3 j

2|

271

CHEVROLET IMPALA | 2O|

CHRYSLER NEWPORT

FORD LTD

LINCOLN-MERCURY LINCOLN

CONTINENTAL

3|

22|

-I

LINCOLN-MERCURY MARQUIS | B|

OLDSMOBILE DELTA 88 | 271

OLDSMOBILE 98 | 14|

PONTIAC BONNEVILLE 151

PONTIAC CATAL1NA | 6|

AMC CONCORD WAGON | 3|

AMC PACER WAGON | i|

OATSUN F-1O WAGON | 4|

OATSUN 510 WAGON | 8|

DATSUN 81O WAGON | 1|

FORD PINTO WAGON | 4|

HONDA CIVIC WAGON | 8|

LINCOLN-MERCURY BOBCAT WAGON | 2|

PONTIAC SUNBIRO SAFARI WAGON | 2|

(CONTINUED)
MRKEM© MODEL

CAKH5ftR» 1978

ALL

N)

STRATA {CAR WAKE AND MODEL

SMALL STN WAGON

MIDSIZE WAGON

LARGE WAGON

TOYOTA COROLLA WAGON

N ]

8|

TOYOTA CORONA WAGON | i|

TOYOTA CRESSIOA WAGON | i|

VOLKSWAGON DASHER WAGON | i|

BUICK CENTURY WAGON | 6|

CHEVROLET MALI8U WAGON | 1S|

CHRYSLER LEBARON WAGON \ i\

DODGE ASPEN WAGON | 15|

DODGE DIPLOMAT WAGON I 1|

DODGE MONACO WAGON | i|

FORD FAIRMONT WAGON | 27|

LINCOLN-MERCURY ZEPHYR WAGON | 13|

OLOSMOBILE CUTLASS CRUISER

WAGON

PLYMOUTH FURY WAGON

.1

PLYMOUTH VOLARE WAGON - | 181

PONT1AC LEMANS SAFARI WAGON | 9|

AMC MATADOR WAGON H

BUICK ESTATE WAGON | »|

CHEVROLET CAPRICE WAGON | 141

CHEVROLET IMPALA WAGON | 121

FORO LTD WAGON | 11|

LINCOLN-MERCURY MARQUIS WAGON 3|

(CONTINUED)
ALL

TABU! 3

M&KE MO MODEL

1978

STRATA

LARGE WAGON

SMALL PICKUP-GAS

______•________-_._______________•______________.___.__-___•_•-_•-______»

|CAR MAKE AND MODEL

OLOSMOB1LE CUSTOM CRUISER

WAGON

SUBCOMPACT DIES

LARGE DIESEL

LG WAGON-DIES

PONTIAC CATALINA SAFARI WAGON

VOLKSWAGON RABBIT

OLDSMOBILE 98

OLOSMOBILE 88

OLDSMOBILE CUSTOM CRUISER

WAGON

4|

241

681

.1

CHEVROLET LUV PICKUP

DATSUN PICKUP

FORD COURIER PICKUP

TOYOTA HILUX

1

1

1

1

4|

7|

3|

STD PICKUP-GAS CHEVROLET EL CAMINO

CHEVROLET C-1O

CHEVROLET C-2O

DODGE D-15O

DODGE D-2OO

FORD F-1OO

FORD F-15O

FORD F-250

FORD RANCHERO

GMC C15OO

GMC C2S00

|CHEVROLET G-1O

29|

3|

"2O|*

.*—- + -

— • -

31

--•-

VAN-GAS

(CONTINUED)
TABU: 3

MAKE AtC KEEL

1978

ALL

•-*

*-

STRATA

VAN-GAS

SPECIAL USE-GAS

SPECIAL USE 4W0

CAR MAKE AND MODEL

CHEVROLET G-2O

DODGE B-1OO

OOOGE B-20O

FORD E-tOO

FORD E-15O

N I

20

3|

9l

M

321

GMC G-15OO | 2|

GMC G-25O0

PLYMOUTH VOYAGER VAN

VOLKSWAGON BUS

(WAGON.KOMBI.CAMPMOBILE)

FORD CLUB WAGON

DODGE SPORTSMAN

CHEVROLET SPORTVAN

CHEVROLET SUBURBAN

GMC RALLY

GMC SUBURBAN

CHEVROLET BLAZER

GMC JIMMY

CHEVROLET SUBURBAN

CHEVROLET BLAZER

GMC JIMMY

DODGE RAMCHARGER

FORD BRONCO

2|

3|

•ol

1 1«l

5|

9|

1 "1

4|

1 2|

1 2|

19|

5|

(CONTINUED)
ALL

TABt£ 3

WKE MO MODEL

OW3fEftR= 1978

STRATA

SPECIAL USE 4 W

STO PKUP DIE 2WO

CAR MAKE AND MODEL

JEEP CHEROKEE

JEEP CJ-1

N I

5|

5|

JEEP CJ-S | 3|

JEEP WAGONEER 6|

PLYMOUTH TRAIL DUSTER | 1|

CHEVROLET C-1O

CMC C-1SOO

18|

3|
TKBt£ 3

MKKE MO MODEL

CAIOEAR= 1979

ALL

-

STRATA

MINI

SUB-COMPACT

CAR MAKE AND MODEL

CHEVROLET CORVETTE (2-SEATER)

DODGE COLT

FORO PINTO

HONDA CIVIC

LINCOLN-MERCURY BOBCAT

VOLKSWAGON BEETLE CONVERTIBLE

HONDA PRELUDE

BUICK OPEL

CHEVROLET CAMARO

CHEVROLET CHEVETTE

CHEVROLET MONZA

DATSUN 21O

OATSUN 31O

DATSUN S1O

OOOGE CHALLENGER

DOOGE COLT HATCHBACK

DODGE OMNI

FORD FIESTA

FORO MUSTANG

HONDA ACCORD

LINCOLN-MERCURY CAPRI

OLDSMOBILE STARFIRE

PLYMOUTH HORIZON

N I

2

1|

1 io|

1 T|

1 2|

1 M

1 '1

1 U

1 '8|

371

1 " 1

1 "|

1 «t

1 2|

1 1|

1 «l

1 U |

1 8|

1 211

1 1»l

1 io|

1 2|

1 »»l
ALL

TftBLE 3

KEEL

1979

N

STRATA

SUB-COMPACT

|CAR MAKE AND MODEL

PLYMOUTH SAPPORO

PONTIAC FIREBIRD

PONTIAC SUNBIRO

TOYOTA CELICA

TOYOTA CELICA SUPRA

TOYOTA COROLLA

TOYOTA CORONA

TOYOTA CRESSIDA

VOLKSWAGON RABBIT

VOLKSWAGON SCIROCCO

5|

2O|

.-.- +

II

- - •

- - •

COMPACT AMC CONCORD

BUICK SKYLARK

CADILLAC SEVILLE

CHEVROLET NOVA

FORD GRANADA

LINCOLN-MERCURV MONARCH

LINCOLN-MERCURY VERSAILLES

OLDSMOBILE OMEGA

-•

3|

MIDSIZE BUICK CENTURY

BUICK REGAL

BUICK RIVIERA

CADILLAC ELDORADO

CHEVROLET MALIBU

1

1

1

1

1

a|

291

«l

31

(CONTINUED)
ALL

TABLE 3

MAKE MOMCOEL

CMttEMt* 1979

STRATA

MIDSIZE

00

|CAR MAKE AND MODEL

CHEVROLET MONTE CARLO

CHRYSLER CORDOBA

CHRYSLER LEBARON

DODGE ASPEN

DODGE DIPLOMAT

DODGE MAGNUM

FORD FAIRMONT

FORD LTD II

FORO THUNOERBIRO

LINCOLN-MERCURY CONTINENTAL

MARK V

PONTIAC GRAND AM

MERCURY COUGAR XR7

- - •

7|

" I

3|

- - •

31

•I

LINCOLN-MERCURY ZEPHYR

OLDSMOBILE CUTLASS

OLDSMOBILE CUTLASS CALAIS

OLDSMOBILE CUTLASS SUPREME

OLDSMOBILE TORONADO

PLYMOUTH VOLARE

PONT1AC GRAND PRIX

PONTIAC LEMANS

1

1

1

1

1

1

1

1

6|

21

471

3|

1*1

2O|

12|

n

LARGE IBUICK ELECTRA

JBUICK LESABRE "aol*

(CONTINUED)
ALL

MSKEM© JctEL

CAKHWt* 1979

STRATA

LARGE

VO

ICAR MAKE AND MODEL

CADILLAC DEVILLE

CADILLAC FLEETWOOD

CHEVROLET CAPRICE

CHEVROLET IMPALA

CHRYSLER NEWPORT

CHRYSLER NEW YORKER

DODGE ST. REGIS

FORD LTO

LINCOLN-MERCURV LINCOLN

CONTINENTAL

LINCOLN-MERCURV MARQUIS

OLOSMOBILE DELTA 88

OLDSMOBILE NINETY-EIGHT

PONTIAC BONNEVILLE

PONTIAC CATALINA

161

- - •

5|

•

"ao|

--- •

SMALL STN WAGON AMC CONCORD WAGON

AMC PACER WAGON

DATSUN 210 WAGON

OATSUN S1O WAGON

DATSUN 8tO WAGON

FORD PINTO WAGON

HONDA CIVIC CVCC WAGON

LtNCOLN-MERCURV BOBCAT WAGON

— •

- - •

3|

(CONTINUED)
ALL

THESE 3

MRKE WBKIEL

OVKYERft* 1979

STRATA

SMALL STN WAGON

|CAR MAKE AND MODEL

PONTIAC SUNBIRO SAFARI WAGON

TOVOTA COROLLA WAGON

TOYOTA CORONA WAGON

VOLKSWAGON DASHER WAGON

2|

MIDSIZE WAGON

00

o

BUICK CENTURY WAGON

CHEVROLET MALIBU WAGON

CHRYSLER LEBARON WAGON

DODGE ASPEN WAGON

OODGE DIPLOMAT WAGON

FORD FAIRMONT WAGON I

LINCOLN-MERCURY ZEPHYR WAGON |

--.-_-_——__—-_-—__---_—--• -

OLDSMOBILE CUTLASS WAGON |

PLYMOUTH VOLARE WAGON

PONTIAC LEMANS SAFARI WAGON

5|

2*1

- - •

4|

3|

241

ao|

LARGE WAGON CHEVROLET CAPRICE

CHEVROLET IMPALA

BUICK ESTATE WAGON

FORD LTD WAGON

LINCOLN-MERCURY MARQUIS WAGON |

-___--___-____-_-_____.-.-____ •

OLDSMOBILE CUSTOM CRUISER

WAGON

PONTIAC BONNEVILLE SAFARI

WAGON

PONTIAC CATALINA SAFARI WAGON |

is]

3|

I .1

I 'I

3|

(CONTINUED)
ALL

TfiBLE 3

MAKE M© MODEL

CARffiRR= 1979

STRATA

SUBCOMPACT DIES

(CAR MAKE AND MODEL

|VOLKSWAGON RABBIT

— •

COMPACT DIESEL 4|

MIDSIZE DIESEL

|CADILLAC SEVILLE

•________•__ _ _- -

CADILLAC ELDORADO

OLDSMOBILE CUTLASS

OLDSMOBILE CUTLASS SUPREME

OLDSMOBILE TORONADO

OLDSMOBILE 88

271

LARGE DIESEL.

IOLDSMO8ILE 98

371

MID WAGON-DIES

LG WAGON-DIES

lOLOSMOBILE CUTLASS CRUISER

[WAGON 21

lOLDSMOBILE CUSTOM CRUISER

IWAGON

SMALL PICKUP-GAS

STD PICKUP-GAS

• _________—__—______ _

CHEVROLET LUV PICKUP

DATSUN PICKUP

DOOGE D5O PICKUP

FORD COURIER PICKUP

TOYOTA HILUX

CHEVROLET C-1O

CHEVROLET C-2O

CHEVROLET EL CAMINO

DOOGE O1OO

DODGE 0 150

DOOGE 0 2OO

FORD F-IOO

___-_»____

1

1

1

1

1

1

1

1

1

1

1

1

5|

4\

3|

«l

2|

341

3|

5|

»l

2|

1|

(CONTINUED)
ALL

TMOX. 3

HBKE AND KEEL

OVtOGAR- 1979

STRATA

STO PICKUP-GAS

(CAR MAKE AND MODEL

FORD F ISO

FORD F 2SO

FORO RANCHERO

GMC CABALLERO

CMC C15OO

2O

5|

- - •

- - •

3|

- - •

VAN-GAS

oo

to

CHEVROLET GtO

CHEVROLET G2O

DODGE B1OO

DODGE B2OO

FORO E-1OO

FORO E-tSO

GMC G1SOO

GMC G-2SOO

VOLKSWAGON BUS

(WAGON.KOMBI.CAMPMOBILE)

FORD CLUB WAGON

DODGE SPORTSMAN

CHEVROLET SPORT VAN

CHEVROLET SUBURBAN

GMC RALLY

GMC SUBURBAN

1

1

I

1

1

1

1

1

1

1

1

1

1

1

t

9|

<3|

M

3|

2O|

U

«l

si

"I

5|

HI

5|

3|

SPECIAL USE-GAS |CHEVROLET BLAZER

SPECIAL USE 4W0

(CONTINUED)

|CHEVROLET BLAZER
ALL

TftBLE 3

MAKE AND MODEL

CAHXEAR= I97 9

STRATA

SPECIAL USE 4W0

STO PKUP DIE 2VD

CAR MAKE AND MOOEL

DODGE RAMCHARGER

FORD BRONCO

GMC JIMMY

JEEP CHEROKEE

N i

19l

10]

JEEP CJ-S . | 41

JEEP CJ-7

JEEP WAGONEER

CHEVROLET C-1O

14

«l

321

GMC C-1S 1 7|

00
TRBUB 3

EM©HOEH

OUWEAR- 1980

ALL

STRATA |CAR MAKE AND MODEL

MINI

SUB-COMPACT

CHEVROLET CORVETTE (2-SEATER)

FORO PINTO

HONDA CIVIC

HONDA PRELUDE

LINCOLN-MERCURY BOBCAT

PLYMOUTH ARROW

AMC EAGLE

AMC SPIRIT

CHEVROLET CAMARO

CHEVROLET CHEVETTE

CHEVROLET MONZA

DATSUN 200 SX

DATSUN 210

OATSUN 310

OATSUN 910

DODGE CHALLENGER

DODGE COLT

DODGE OMNI

FORO FIESTA

FORO MUSTANG

HONDA ACCORD

LINCOLN-MERCURY CAPRI

OLDSMOBILE STARFIRE

1

j

I

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

N

1

111

"1

5|

al

2|

s

n

io|

461

I'M

io|

" I

6|

1|

13|

35|

3*1

t|
3

«ND MOnet,

RR 1980

ALL

oo

STRATA

SUB-COMPACT

COMPACT

MIDSIZE

CAR MAKE AND MODEL

PLYMOUTH CHAMP

PLYMOUTH HORIZON

PLYMOUTH SAPPORO

PONTIAC FIREBIRD

PONT1AC SUNBIRD

TOYOTA CELICA

TOYOTA CELICA SUPRA

TOYOTA COROLLA

TOYOTA COROLLA TERCEL

TOYOTA CORONA

TOYOTA CRESSIOA

VOLKSWAGON JETTA

VOLKSWAGON RABBIT

VOLKSWAGON RABBIT CONVERTIBLE

VOLKSWAGON SCIROCCO

AMC CONCORD

AMC PACER

BUICK SKYLARK

FORD GRANADA

LINCOLN-MERCURY MONARCH

OLDSMOBILE OMEGA

BUICK CENTURY

BUICK REGAL

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

N

8

18|

'1

2O|

18|

H

42|

23|

51

1|

1|

161

2|

4|

12|

1|

3|

26|

23|

441

(CONTINUED)
ALL

DMXB

CRRStEBft. 1980

STRATA

MIDSIZE

oo

|CAR MAKE AND MODEL

•--_-——-—-.__-— -

BUICK RIVIERA

CADILLAC ELDORADO

CADILLAC SEVILLE

CHEVROLET CITATION

CHEVROLET MALIBU

CHEVROLET MONTE CARLO

CHRYSLER CORDOBA

CHRYSLER LEBARON

DODGE ASPEN

DODGE DIPLOMAT

OQOGE MIRADA

FORD FAIRMONT

FORD THUNDERBIRD

LINCOLN-MERCURY COUGAR XR7

LINCOLN-MERCURY ZEPHYR

OLDSMOBILE CUTLASS

OLOSMOBILE CUTLASS CALAIS

OLDSMOBILE CUTLASS SUPREME

OLDSMOBILE TORONADO

PLYMOUTH VOLARE

PONTIAC GRAND PRIX

PONTIAC LEMANS

I

1

1

1

1

1

|

|

1

1

1

I

I

1

|

12O|

351

361

5|

"1

"I

t|

521

4|

"1

1O|

PONTIAC PHOENIX

(CONTINUED)
TRBtZ 3

WWE MB KCEL

1980

ALL

00

•vl

STRATA

LARGE

SMALL STN WAGON

CAR MAKE AND MODEL

BUICK ELECTRA

BUICK LESABRE

CADILLAC DEVILLE

CADILLAC FLEETWOOD

CHEVROLET CAPRICE

CHEVROLET IMPALA

CHRYSLER NEWPORT

CHRYSLER NEW YORKER

DODGE ST. REGIS

FORD LTO

LINCOLN-MERCURY CONTINENTAL

LINCOLN-MERCURV CONTINENTAL

MARK VI

LINCOLN-MERCURY MARQUIS

OLDSMOBILE DELTA 88

OLOSM08ILE NINETY-EIGHT

PONTIAC BONNEVILLE

PONTIAC CATALINA

AMC CONCORD WAGON

DATSUN 31O WAGON

DATSUN 510 WAGON

DATSUN 810 WAGON

DODGE COLT WAGON

1

11

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

N I

4|

• 1

4|

3|

"1

12|

'1

21

"1

n

4|

5|

•1

n

3|

(CONTINUED)
ALL

"BHtB 3

NKKE AID MODEL

CWHEBR- 1980

oo

STRATA

SMALL STN WAGON

MIDSIZE WAGON

LARGE WAGON

SUBCOMPACT DIES

(CONTINUED)

|CAR MAKE AND MODEL

FORD PINTO WAGON

HONDA CIVIC WAGON

LINCOLN-MERCURY BOBCAT WAGON |

TOYOTA COROLLA WAGON

TOYOTA CRESSIDA WAGON

VOLKSWAGON DASHER WAGON

IVOLKSWAGON RABBIT

ial"

2|

BUICK CENTURY WAGON

CHEVROLET MALIBU WAGON

CHRYSLER LEBARON WAGON

DODGE ASPEN WAGON

FORD FAIRMONT WAGON

LINCOLN-MERCURY ZEPHYR WAGON

OLOSMOBILE CUTLASS WAGON

PLYMOUTH VOLARE WAGON

PONTIAC LEMANS SAFARI WAGON

1

1

I

1

t

1

1

1

1

6|

211

2|

5|

28|

•1

<2|

«l

41

BUtCK ESTATE WAGON

CHEVROLET CAPRICE WAGON

CHEVROLET IMPALA WAGON

FORD LTD WAGON

OLOSMOBILE CUSTOM CRUISER

WAGON

PONT1AC CATALINA SAFARI WAGON

1

1

1

1

|

1

2|

31

31

4|

•1
TABIE 3

MAKE MO MODEL

CAISEAR- 1980

ALL

STRATA

MIDSIZE DIESEL

LARGE DIESEL

SMALL WAGON-DIES

MID WAGON-DIES

LG WAGON-DtES

SMALL PICKUP-GAS

CAR MAKE AND MODEL

CADILLAC ELDDRADO

CADILLAC SEVILLE

OLDSMOBILE CUTLASS

OLDSMOBILE CUTLASS CALAIS

OLOSMOBILE CUTLASS SUPREME

OLDSMOBILE TORONADO

BUICK ELECTRA

BUICK LESABRE

CADILLAC DEVILLE

CADILLAC FLEETWOOO

PONTIAC BONNEVILLE

OLDSMOBILE 88

OLOSMOBILE 98

VOLKSWAGON DASHER

OLOSMOBILE CUTLASS CRUISER

WAGON

CHEVROLET CAPRICE WAGON

CHEVROLET IMPALA WAGON

OLOSMOBILE CUSTOM CRUISER

WAGON

BUICK ELECTRA ESTATE WAGON

PONTIAC BONNEVILLE WAGON

CHEVROLET LUV PICKUP 2WD

DATSUN PICKUP 2WO

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

N I

4

5|

3|

431

6

7|

1O|

8

2|

161

3O|

5|

18

28|

el

11

ITJ

(CONTINUED)
TRBtB 3

WKEMOHXEL

CAIOEftR- 1980

ALL

VO

O

STRATA |CAR MAKE AND MODEL

SMALL PICKUP-GAS

STD PICKUP-GAS

VAN-GAS

DODGE D5O PICKUP 2ND

FORD COURIER PICKUP 2W0

PLYMOUTH ARROW PICKUP 2WD

TOYOTA PICKUP 2WD

VOLKSWAGON PICKUP 2V0

CHEVROLET CIO PICKUP 2W0

CHEVROLET C20 PICKUP 2W0

N

9

1 «M

»l

7|

3|

1 24|

'1

CHEVROLET EL CAMINO PICKUP 2W0| 6|

DODGE D1S0 PICKUP 2W0

DODGE O2OO PICKUP 2HD

FORD F100

FORD F15O PICKUP 2WD

FORD F250 PICKUP 2WD

GMC CIS PICKUP 2WO

GMC C25 PICKUP 2WO

TOYOTA PICKUP 3/4 TON 2WD

CHEVROLET GtO VAN

CHEVROLET G20 VAN

CHEVROLET G20 SPORTVAN

DODGE 8100 VAN

DODGE 8200 VAN

DODGE 8100 SPORTSMAN

DODGE 8200 SPORTSMAN

8|

1 '1

1 231

1S|

i 2 |

1 s|

1 *l

1 8|

1 4|

1 3|

1 '1

1 ' 2|

| 1|

(CONTINUED)
TABUS 3

MAKE N © KEEL

CMWERR= 198 0

ALL

STRATA

VAN-GAS

SPtClAL USE-GAS

SMALL PICKUP 4W0

STD PICKUP 4M0

SPECIAL USE 4WO

CAR MAKE AND MODEL

DODGE B3OO SPORTSMAN

FORO E 100 CLUB WAGON

FORO E ISO CLUB WAGON

GMC G2S VAN

PLYMOUTH PB1OO VOYAGER

VOLKSWAGON VANAGON

CHEVROLET CIO BLAZER

CHEVROLET CIO SUBURBAN

CHEVROLET C2O SUBURBAN

CHEVROLET LUV

TOYOTA PICKUP

CHEVROLET K-1O

CHEVROLET K-20

DODGE DtSO

DODGE W2OO

FORO F15O

FORO F25O

GMC K15

JEEP J10

CHEVROLET K10 BLAZER

CHEVROLET KtO SUBURBAN

DODGE AW100 RAMCHARGER

FORO BRONCO

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

1

N I

2

4|

«4|

1

M

U

2|

1

2O|

241

15|

"1

2|

H

241

11|

4

2|

4|

1|

2|

19|

(CONTINUED)
3

M

1980

ALL

STRATA

SPECIAL USE 4W0

SML PKUP DIE 2WJ

SID PKUP DIE 2ND

-_-•._-«—..——•__,»•«»«_••«<»•_..——•.—_.•_—..—_.••..•__..—_—...•.—.._—«_.._——•..*+».—«—«-»...•_«.

| CAR MAKE AND MOOEL

GMC K1S JIMMY

GMC K1S SUBURBAN

JEEP CHEROKEE

JEEP CJ-S

JEEP CJ-7

-.-—-.------_._---_-.-—----.«--—_..-__

JEEP tfAGONEER

PLYMOUTH PW1OO TRAIL OUSTER

|VOLKSWAGON

3|

-•

1|

to I

CHEVROLET C-IO

GMC CIS
•raaue 3

MAKE MID MXEt.

1981

ALL

vo

CO

STRATA

MINI

SUB-COMPACT

CAR MAKE AND MODEL

CHEVROLET CORVETTE (2-SEATER)

DATSUN 28OZX (2-SEATER)

HONDA CIVIC

HONDA PRELUDE

TOYOTA STARLET

N

3

5

46

2O

12

AMC EAGLE | 1

AMC EAGLE KAMMBACK SX4

AMC SPIRIT

3

7

CHEVROLET CAMARO | 12

CHEVROLET CHEVETTE

DATSUN 2OOSX

1O5

10

DATSUN 21O | 29

DATSUN 28OZX 2*2

DATSUN 3 to

DATSUN S1O

2

6

5

OATSUN 810 | 1

DODGE CHALLENGER

DODGE COLT

DODGE O24

FORD MUSTANG

HONDA ACCORD

LINCOLN-MERCURY CAPRI

2

B

21

S2

PLYMOUTH CHAMP | 1O
TABIB 3

HAKE MID MODEL

CATOEftR" 198 1

ALL

vO

STRATA

SUB-COMPACT

•

CAR MAKE AND MODEL

PLYMOUTH SAPPORO

PLYMOUTH TC3

PONTIAC FIREBIRD

TOYOTA CELICA

TOYOTA CELICA SUPRA

TOYOTA COROLLA

TOYOTA COROLLA TERCEL

TOYOTA CORONA

TOYOTA CRESSIOA

VOLKSWAGON RABBIT

VOLKSWAGON SCIROCCO

1

1

1

1

1

1

1

1

1

1

1

1

6

1G|

G|

35|

2|

661

43|

6

8|

•1

H

COMPACT

MIDSIZE

AMC CONCORD

BUICK SKYLARK

DODGE OMNI

FORD ESCORT

LINCOLN-MERCURY LYNX

OLDSMOBILE OMEGA

PLYMOUTH HORIZON

BUICK CENTURY

BUICK REGAL

BUICK RIVIERA

CAOILLAC ELDORADO

CADILLAC SEVILLE

1

1

I

1

|

I

|

1

1

1

2|

« 3|

321

321

3S|

4|

a|

(CONTINUED)
AND MODEL

CMOfEftft. 1981

ALL

vx>

STRATA

MIDSIZE

CAR MAKE AND MODEL

CHEVROLET CITATION

N I

77

CHEVROLET MALIBU | 19|

CHEVROLET MONTE CARLO

CHRYSLER CORDOBA

CHRYSLER IMPERIAL

CHRYSLER LEBARON

291

4|

2|

«l

DODGE ARIES | 31|

DODGE OIPLOMAT | i|

DODGE MIRADA

FORD FAIRMONT

FORD GRANADA

FORD THUNDERSIRD

LINCOLN-MERCURY COUGAR

LINCOLN-MERCURY XR7

LINCOLN-MERCURY ZEPHYR

OLDSMOBILE CUTLASS

OLOSMOBILE CUTLASS CALAIS

OLDSMOBILE CUTLASS SALON

OLOSMOBILE CUTLASS SUPREME

PLYMOUTH RELIANT

PONTIAC GRAND PRIX

PONTtAC LEMANS

PONTIAC PHOENIX

*l

19|

19|

«l

1|

3|

5|

22|

el

"I

41|

341

371

1O|

371

(CONTINUED)
CDEL

CMttEAR= 1981

ALL

STRATA

LARGE

|CAR MAKE AND MODEL

BUICK ELECTRA

BUICK LESA8RE

CADILLAC DEVILLE

CADILLAC FLEETWOOD

CHEVROLET CAPRICE

CHEVROLET IMPALA

CHRYSLER NEWPORT

CHRYSLER NEW YORKER

FORD LTD

LINCOLN-MERCURY MARQUIS

OLOSMOBILE DELTA 88

OLDSMOBILE NINETY-EIGHT

PONT I AC BONNE V RL E

PONTIAC CATALINA

LINCOLN MARK VI

1

1

1

1

1

i

1

1

1

1

1

1

1

1

io|

t|

1*1

s|

i|

1|

7|

8|

" |

«l

13|

1|

5|

LINCOLN CONTINENTAL TOWN ft

COUNTRY .ol

SMALL STN WAGON AMC EAGLE WAGON

AMC CONCORD WAGON

OATSUN 21O WAGON

OATSUN 51O WAGON

OATSUN 81O WAGON

HONDA CIVIC WAGON

S|

"aij"

(CONTINUED)
TABLE 3

JWDHDDEL

CRBYERR. 198 1

ALL

vo

STRATA

SMALL STN WAGON

MIDSIZE WAGON

LARGE WAGON

CAR MAKE AND MODEL

TOYOTA COROLLA WAGON

TOYOTA CORONA WAGON

TOYOTA CRESSIDA WAGON

BUICK CENTURY WAGON

CHEVROLET MALIBU WAGON

CHRYSLER LEBARON WAGON

DODGE ARIES WAGON

FORD FAIRMONT WAGON

LINCOLN-MERCURY ZEPHYR WAGON

OLDSMOBILE CUTLASS WAGON

PLYMOUTH RELIANT WAGON

N I

361

5|

2|

21|

2|

381

ia|

t|

101

«l

PONTIAC LEMANS SAFARI WAGON | 1O|

CHEVROLET CAPRICE 4|

CHEVROLET IMPALA | 6|

BUICK ELECTRA ESTATE WAGON | 1|

FORD LTD WAGON «l

LINCOLN-MERCURY MARQUIS WAGON | 3|

OLDSMOBILE CUSTOM CRUISER I I

WAGON I 31

PONTIAC BONNEVILLE SAFARI 1 1

WAGON 1 _|

SUBCOMPACT DIES |VOLKSWAGON RABBIT | 741

MIDSIZE DIESEL CADILLAC ELDORADO | 3|

OLDSMOBILE CUTLASS ail

(CONTINUED)
MAKE ANDHXEt.

C7VFKERR. 1981

ALL

00

STRATA |CAR MAKE AND MODEL

MIDSIZE DIESEL

LARGE DIESEL

SMALL WAGON-DIES

MID WAGON-DIES

LG WAGON-DIES

SMALL PICKUP-GAS

OLDSMOBILE CUTLASS CALAIS

OLDSMOBILE CUTLASS SUPREME

PONTIAC GRAND PRIX

OLDSMOBILE TORONAOO

BUICK ELECTRA

BUtCK LESABRE

CADILLAC DEVILLE

CADILLAC FLEETWOOD

CHEVROLET CAPRICE

CHEVROLET IMPALA

PONTIAC BONNEVtLLE

OLDSMOBILE 88

OLDSMOBILE 98

VOLKSWAGON DASHER

OLDSMOBILE CUTLASS CRUISER

WAGON

BUICK ELECTRA ESTATE WAGON

OLOSMOBILE CUSTOM CRUISER

WAGON

CHEVROLET CAPRICE WAGON

PONTIAC BONNEVILLE WAGON

CHEVROLET LUV PICKUP

DATSUN PICKUP

DODGE RAMSO PICKUP

M 1 " 1

1

el

341

61

4|

3|

ail

"I

I 2|

1 «l

1 2O|

(CONTINUED)
3

1981

ALL

STRATA

SMALL PICKUP-GAS

|CAR MAKE AND MOOEL

FOOD COURIER PICKUP

PLYMOUTH ARROW PICKUP

TOYOTA TRUCK

VOLKSWAGON PICKUP

1|

121

STD PICKUP-GAS CHEVROLET CIO PICKUP

CHEVROLET C2O PICKUP

CHEVROLET EL CAMINO PICKUP

DOOGE O1SO PICKUP

DODGE D25O PICKUP

FORO F1OO

FORD F1SO PICKUP

FORD F2SO PtCKUP

GMC C49 PICKUP

GMC C2S PICKUP

TOYOTA PtCKUP 3/4 TON

CHEVROLET G2O VAN

<M

H

26|

VAN-GAS

CHEVROLET G1O SPORTVAN

CHEVROLET G2O SPORTVAN

DOOGE B15O VAN

DODGE B2SO VAN

DODGE B«5O SPORTVAN

DODGE 8230 SPORTSMAN

FORO E10O ECONOLINE

I-•-

I

-•-

I

21

31

(CONTINUED)
TRBI£ 3

E AND MOtEL

1981

ALL

o

o

STRATA

VAN-GAS

SPECIAL USE-GAS

SMALL PICKUP 4MD

STD PICKUP 4WD

CAR MAKE AND MODEL

FORD E15O ECONOLINE

FORD E25O ECONOLINE

GMC G15 VAN

GMC G2S VAN

GMC G25 SPORTVAN .

PLYMOUTH PB15O VOYAGER

VOLKSWAGON VANAGON

CHEVROLET CIO BLAZER

CHEVROLET CIO SUBURBAN

CHEVROLET C2O SUBURBAN

GMC C15 SUBURBAN

CHEVROLET LUV

DATSUN

TOYOTA PICKUP

CHEVROLET K-1O

CHEVROLET K-2O

DODGE W15O

DODGE W2SO

FORD F150

FORO F25O

N I

•1

2|

3|

1|

a|

4|

3|

4|

1 H

s|

1 "1

23|

1|

4O|

1 f\

GMC K1S | 1|

GMC K25

JEEP «I1O

«l

al

(CONTINUED)
TABIE 3

AND HXEL

1981

ALL

STRATA

STO PICKUP 4WD

|CAR MAKE AND HOOEL

|JEEP 020

to

SPECIAL USE 4W0 CHEVROLET K1O BLAZER

DODGE AV1OO RAMCHARGER

FORD BRONCO

GMC K15 SUBURBAN

JEEP CJ-5

JEEP CJ-7

JEEP CJ-B (SCRAMBLER)

JEEP WAGONEER

TOYOTA LAND CRUISER WAGON

1

1

1

1

1

1

1

1

1

7I

3|

13|

3|

5|

H

"sal"

4 5l

SML PKUP DIE 2WD ITOYOTA

IVOLKSWAGON

STO PKUP OIE 2WD I

CHEVROLET C-1O

GMC CIS
APPENDIX B 

ESTIMATION OF AVERAGE VEHICLE AGE 

 

202 
Month (Yr)

October '76

November '76

December '76

January '77

February '77

March '77

April '77

May '77

June '77

July '77

August '77

September '77

October '77

November '77

December '77

Vehicle

Sales'*

730,216

720,772

694,457

601,325

665,978

895,319

B21.969

833,333

919,142

731,033

726,422

656,600

869,920

737,362

645,991

ESTIMATION OF AVERAGE

FROM

VEHICLE SALES

Proportion of

Monthly Sales

Assumed to Be

Model Yr 1977

2/3

3/4

ALL

•t

n

•i

n

n

ii

•I

• «i

II

1/3

1/4

None

VEHICLE AGE

DATA

S Sales

by Month,

Model Yr

1977

5.36

6.40

7.64

6.62

7.33

9.85

9.04

9.17

10.11

8.04

7.99

7.23

3.19

2.03

0

Average

Vehicle Age,

in months

as of

1 July 1978

20.5

19.5

18.5

17.5

16.5

15.5

14.5

13.5

12.5

11.5

10.5

9.5

8.5

7.5

Source: a - Automotive News, various weekly publications for 1976 - 1978.

203
The average vehicle age for the 1977 Model Year fleet, as of 1 Duly 1978,

is computed from the above table by taking the sales-weighted average of

the individual monthly ages of the vehicles (e.g., the sum of the products

of the numbers in columns 4 and 5 of the table). This number turns out to

be:

14.34 months = 1.195 years

or approximately 1.2 years.

Thus on 1 Duly 1983, the midpoint of the 1983 On-Road Survey, Model Year

1977 vehicles would be approximately 1.2 • 5 or 6.2 years old.

Note in column 3 of the table that all vehicle sales from December 1976

through September 1977 are considered to be 1977 Model Year vintage,

whereas only portions of the sales for months October and November 1976,

and October and November 1977 are considered to be Model Year 1977

vehicles. This is done to account for the sale of carry-over model year

vehicles into the beginning of the subsequent model year.

The year 1977 has been assumed as typical insofar as portraying the

distribution of vehicle sales by month, and hence the computation of

average vehicle age, as used in Chapter 3 of the report.

20A
APPENDIX C

SURVEY SUPPORT MATERIALS

205
O.H.B. No. 2127-0037

Explra* 9/30/84

US Department 400 s**nth St., s.w.

Of TtanspOftatiOn Washington, D.C. 20590

NcrHoool HJflhwoy

ltofflc Safety AdmW8tratten

 PRENOTtFICA TION

LETTER ~ NHTSA

Dear Driver:

We need your help . . .

Your name has been selected at random from among all owners of

late model cars and light trucks to participate 1n a nationwide

survey.

The National Highway Traffic Safety Administration, an Agency of

the U.S. Department of Transportation, 1s sponsoring the survey

to measure the gas mileage performance of late model vehicles.

Information obtained 1n the survey will tell us how much the Nation

1s saving as a result of the more fuel-efficient vehicles produced

1n the last few years, and will help determine future directions

1n energy conservation efforts.

The National Opinion Research Center, an experienced survey firm,

will conduct the study for us. Within the next few days, they

will be sending you a copy of a simple fuel-mileage log. Completion

of the log will require only a few minutes of your time; The

Information, of course, will be vital to our study but we believe

you will find 1t personally useful as well.

We want to assure you that while your participation 1n this survey

1s entirely voluntary, your response 1s very Important to ensure

the accuracy of the results. The survey complies with all Federal

regulations concerning privacy and confidentiality and the results

will be used only 1n statistical summaries.

We look forward to your cooperation In this Important undertaking.

Sincerely,

ZL,

Barry Felrice

Assoc1ateAdm1n1strator for

Plans /nd Programs

206
J/JO/M

tear

I f you are like most of us, you have become very aware of the high cost of

gasoline 1n today's family budget. "M11es-per-gal1on" Is the firs t thing

most of us think of when we shop for a new or used car or truck.

In order to meet the problems of fuel conservation and cost, automobile

companies have been manufacturing smaller and lighter vehicles 1n recent

years.

We have been asked by the National Highway Traffic Safety Administration

(see letter enclosed] to find out just how efficient these new vehicles

have become. To do this , we are conducting a nationwide survey of vehicle

owners like yourself who have purchased these late models.

How can you help us? By keeping a simple record of your gas purchases over

the next month for the vehicle listed below.

In a few days, we will send you a small fuel-mileage log. Completion of the

log will take only a few minutes of your time. In the event you no longer

own the vehicle, or will not be operating I t next month, please detach the

form below and return 1t to us as soon as possible.

We look forward to your participation In this Important study.

Sincerely,

Jean Attu

Jean Atkinson

Senior Survey Director

Conducted by: NUIonal Opinion feMircnConMr • tMO South till* • CMcago. 1110637

UnWnltyolCnlMQO

! PLEAVEDETACH THIS FOnM'AMDHlwnNmTHBPoifAQYiMDyNvYLO

1

 VIHICU: HAKE MODEL YIAW I I I I 1 I I I

I to «M* talk** |mM t

I :Tft*NhMtlMitMMM I | | N«IOlM|lMtomiMMiri*««ft*«»«nan»wliMilii

BipCod»)_

207
O.H.B. No. 2127-0037

Enplrtt 9/30/84

USDepartment - • 400 8M» * st., s.w.

of TrnnsDortotion WMhmgton. DC. 20590

National Highway

ON TH€ RORD FU€L €COHOMV SURV6V

QU£STIONNAIR£ TRANSMITTAL LETTER

Dear Driver: /7/?57 W4V£" "~

A few days ago we wrote that you had been chosen to participate 1n a

national On The Road Fuel Economy Survey.

Enclosed 1s a Fuel Mileage Log and two decais for this U.S. Department of

Transportation study. The Log should be kept 1n some convenient spot Inside

your vehicle next month for ready access at "fill-up" time. One of the

decals can be placed on the dash near the fuel gauge, as a reminder to you,

or anyone else who drives, to record each gas purchase for the month. The

decal can be easily removed after the survey, and will leave no residue on

your vehicle.

Before placing the Log 1n your vehicle, please complete the description of

your vehicle In Section A. Then, each time you buy gas next month, simply fill

1n one line of Section B, the Gas Mileage Log.

Please try to fill the tank completely, at least for the first and last

purchases of the month, to enable us to make good estimates of your mileage.

At the end of the month, please return the Log to us. Simply fold the Log as

Indicated, seal with (second) decal or tape, and drop 1t In the mall. No

postage 1s needed.

Because we believe you may find a record of your fuel mileage personally

useful, we have enclosed a handy booklet which you may keep for yourself.

You may also find the booklet a convenient place to keep the Log during the

survey month.

The Information you supply will be an Important aid 1n determining future

energy needs of our country, and we are looking forward to your participation

1n our study.

Thank you for your help.

Sincerely,

Jean Atkinson

Senior Survey Director

Enclosures

Conducted t>y *'*t'on*l Opinion Rwsejfch Center • 6030 South E'lis • Chicago, IL 60837

l C ••„:>

208



O.M.B. No. 2127^-0037

Explrtt 5/30/8*

U S Deportment 400 swmtn si., s.w.

of Transportation wainmgton, D,C. 20500

National Highway

tattle Safety

Administration r\M TU£ RQRD FU€L 6COROMV SURV€V

TRANSMITTAL LETTER -

Dear Driver: SECOND WAVE

About two months ago we wrote to say that you had been selected to participate

in our national On the Road Fuel Economy Survey. Because our letters and Fuel

Mileage Log may not have reached you* we are writing again to ask for your help.

Enclosed 1s a Fuel Mileage Log and two decals for this U.S. Department of

Transportation study. The Log should be kept 1n some convenient spot Inside

your vehicle next month, for ready access at "f1ll-up" time. One of the

decals can be placed on the dash near the fuel gauge, as a reminder to you,

or anyone else who drives, to record each gas purchase for the month. The

decal can be easily removed after the survey and will leave no residue on

your vehicle.

Before placing the Log in your vehicle, please complete the description of

your vehicle in Section A. Then, each time you buy gas next month, simply

fill in one line of Section B, the Gas Mileage Log. Please try to fill the

tank completely, at least for the first and last purchases of the month, to

enable us to make good estimates of your mileage.

At the end of the month, please return the Log to us. Simply fold the Log

as Indicated, seal with second decal or tape, and drop 1t in the mall. No

postage 1s needed.

Because we believe you may find a record of your fuel mileage personally

useful, we have enclosed a handy booklet which you may keep for yourself.

You may also find the booklet a convenient place to keep the Log during the

survey month.

The Information you supply will be an important aid in determining future

energy needs of our country, and we are looking forward to your participation

In our study.

Thank you for your help.

Sincerely,

Jean Atkinson

Senior Survey Director

Enclosures

National Oe> •... •• ; • : • ..'•• • &'jijfec.*fitn.s • CmctgcH.ttoe37

University of Cue;-;,•. us wwmiw mvm:. cwci

212
TELEPHONE Qt/ES TIQNNAIRE

FORM APPROVED THRU 9/jO/B*

O.H.B. NO. 2127-0037

ON THE ROAD NONRESPONSE FOLLOVUP

TELEPHONE QUESTIONNAIRE

THE SALUTATION AND CLOSING OF THE INTERVIEWER'S MESSAGE WILL BE AS FOLLOWS:

Salutation - "Hello (name). This is (INTERVIEWER'S NAME) from the National

Opinion Research Center of the University of Chicago. I as calling to check

whether you received any of the letters we have sent to you In the past

sonth(s) about the national On The Road Survey we are conducting for the

Department of Transportation." (On to Questionnaire Item 1)

IF RESPONDENT VOLUNTEERS THAT HE OR SHE HAS RECEIVED NO INFORMATION

INTERVIEWER WILL EXPLAIN, "We have been asked by the National Highway Traffic

Administration to find out just how efficient new vehicles have become in

miles per gallon for the average motorist. To do this, we are conducting a

nationwide survey of late model vehicles* and we understand that you own

one.* (On to Questionnaire Item 2)

Closing - IF THE RESPONDENT IS RELUCTANT TO PARTICIPATE THE CALL WILL BE

POLITELY TERMINATED WITH THE INTERVIEWER EXPRESSING GRATITUDE FOR HIS OR HER

COOPERATION IN RECEIVING THE CALL.

- IF THE RESPONDENT AGREES TO ACCEPT LOG THE INTERVIEWER WILL SAY

"Thank you for agreeing to help us in this survey, the information

you supply will be an important aid in the development of more fuel*

efficient vehicles in this country*

Within a few days you will receive a fuel mileage log and a

complimentary booklet from the Department of Transportation.

Recording your gas purchases will be simple if you keep the log In

your vehicle. Thank you again."

213
Phan* yuisiiohrAJr* -

-2-

Telephone Interview

(See introduction page)

1. Did you receive any of our recent letters about this survey?

No I 2

2. Have you ever owned

(READ Label Below)

Make:

IF YES

Do you

Model: Year:

TO 2:

still own this vehicle?

What became of the vehicle?

It was

It was

Other

Yes

No

Yes

No

sold

junked

specify*

CD

1—I

1—1

(—i

I—i

i—i

I—i

i

2

1

2

1

2

3

ASK 3

GO TO 5B AND

END

ASK

ASK

ASK

INTERVIEW

6

4

5

5. A. Do you have the name and address of the person to whom it was sold?

(Name)

(Address)

(Town) (Zip)

B. THANK RESPONDENT AND TERMINATE INTERVIEW IF RESPONDENT NO LONGER OWNS

CAR.

•INTERVIEWER INSTRUCTION—CONTINUE INTERVIEW IF CAR IS STILL OWNED/USED BY

PERSON(S) IN RESPONDENT'S HOUSEHOLD.

214
PhonQ qaBstlonn&tre - -3-

6. He are trying to Improve our survey procedures and I would like to ask

you a few questions about why you were unable to participate in the On

the Road Survey* This should take only a few minutes of your tine.

why were you unable to complete the fuel mileage log?

Did not drive the vehicle .......

Did not wish to participate »••••

Too busy ..««....«.««««««..«.<«•.

Object to surveys

(Probe "Why is that?")

Did not understand about the

survey or task (Probe:

"What was it you didn't

understand?")

Other reason (SPECIFY)

1 ASK 7

2'

3

ASK 8

7. Is the car now back on the road?

Yes

No

1 I 1 GO TO 8

2 GO TO 5B END

INTERVIEW

8. I have a few questions about your vehicle.

INTERVIEWER COMPLETE FACSIMILE OF CAR MILEAGE LOG NEXT PAGE AND CHECK

BELOW.

Section A & B completed I 1 1

Not completed (give reason) ... 1 I 2

215
PAoot? questionnaire

5ECTHW A - VEHICLE IWrOwnATIOH

MtC

1. The vehicle we want Information about 1s your:

2.

3.

4.

S.

BODY STYLE

CAR:

a .

TRUCK:

b. TYPE

DRIVE:

AIR CONDITI

D2-0oor

OP1ck-up

1-,2-Wheel

LJDrive

ONED

RADIAL TIRES —. •

•Yes

ENGINE

a. NO. OF D a

CYLINDERS

b. TURBOCHARGEO

c. FUEL

d. FUEL

SYSTEM

DY«

OGasoline

Ocarburetor

•4-0oor

Dvan

,-,4-Wheel

LJOrivc

DNO

De

DNO

Ddesel

—Station

Dragon

Djeep, B

Bronco,

D4

DFUCI Injection

e. SIZE/DISPLACEMENT I I \ jCubic I 1 I I ICubic

(Fill 1n only one) • •' ^Inches' 1 '• ' LJCent1weters

Ds-Spttd

6. TRANSMISSION _ _ .

MANUAL: U 3-Speed U4-Spee d

AUTO- D3-Spee<t D4-Speed

MAT1C

7 . VEHICLE MAINTENANCE.

Within the last 3-months mm'

has the vehicle had (Check MTune-up

all that apply )

8. VEHICLE

OWNERSHIP

DOWNED

Alignment

DLEASED

•ML HKL T(M

DTruck-based Station Wagon

(e.g.. Suburban, etc.)

Liters

•T1re Pressure

Check

Dcompany Car

SECTION B - SAS MILEAGE LOG

17. What type of driving have you done recently, 1n the month

of (Record month) In your (Name vehicle)?

TYPE DRIVING EACH PERIOD

a. Was 1t mostly dt y or mostly highway by which I mean

20-45 mph, short trips or 50-55 moh driving?

b. Old driving Involve heavy usage such as towing,

off-road use, heavy loads, or In snow?

 w "inB »

Mostly Mostly

City Highway

ivv Usage

Yes

Mo

19. (See concluding remarks page 1.)

t t 1 6o to 19

t t 2

216
O.N.B. No. 2127-0037

Explr** 3/30/84

US Department 400 swtnth St., s.w.

of lansponation wuhtyton, DJC. 20500

National Mghwa y

Ttwfflc Sofsty

ON TH€ RORD FU€L €COnOMV SURV€V

GLi/ZSTIONNAlRE TRANSM1TTAL LETTERDear Driver:

Thank you for agreeing to participate 1n our Important survey of On

The Road Fuel Economy.

Enclosed Is a Fuel Mileage Log and two decals for this U.S. Department

of Transportation study. The Log should be kept 1n some convenient spot

Inside your vehicle next month, for ready access at "fill-up" time. One

of the decals can be placed on the dash near the fuel gauge, as a

reminder to you, or anyone else who drives, to record each gas purchase

for the month. The decal can be easily removed after the survey and will

leave no residue on your vehicle.

Before placing the Log 1n your vehicle, please complete the description

of your vehicle 1n Section A. Then, each time you buy gas next month,

simply fill in one line of Section B, the Gas Mileage Log. Please try

to fill the tank completely, at least for the first and last purchases

of the month, to enable us to make good estimates of your mileage.

At the end of the month, please return the Log to us. Simply fold the

Log as Indicated, seal with second decal or tape, and drop 1t in the

mall. No postage 1s needed.

Because we believe you may find a record of your fuel mileage personally

useful, we have enclosed a handy booklet which you may keep for yourself.

You may also find the booklet a convenient place to keep the Log during

the survey month.

The Information you supply will be an Important aid 1n determining future

energy needs of our country, and we are looking forward to your

participation in our study.

Thank you for your help.

Sincerely,

Jean Atkinson

Senior Survey Director

Enclosures

National Opinion ..»«,en i^mer • fc&Sb*'inUti» • Covcaeo, It 60637

Unlyrttty of Chicago

217
APPENDIX D

METHODOLOGY AND DATA FOR ESTIMATING REDUCED ENERGY

CONSUMPTION AND EQUIVALENT DOLLAR VALUE

218
ANNUAL AND LIFETIME MILEAGE ESTIMATES, AVERAGE PASSENGER CAR

AND LIGHT TRUCK

In order to estimate total lifetime reduction in energy

consumption and dollar equivalent values for the vehicles studied in the

On-the-Road Fuel Economy Survey, it is necessary to have an estimate of the

total miles that an average vehicle will travel in its lifetime and also an

estimate of how this mileage is distributed by the age of the vehicle.

In Chapter 3, Table 3-10, estimates were developed for the average

vehicle miles per vehicle age for the U.S. population of privately^ owned

passenger cars and light trucks. These estimates constitute the principal

basis for estimating lifetime and yearly miles traveled for the average

vehicle. Two adjustments must be made to these data, however, before they

can be used to estimate total lifetime reductions in energy consumption and

dollar equivalent values.

First, an adjustment must be made to account for the miles driven

by fleet vehicles, which were not sampled in the survey. Fleet vehicles are

known to be newer, in general, and also to be driven, on a per vehicle

basis, more miles annually than the average vehicle in the U.S. population.

Secondly, the miles per year data in Table 3-10 represent travel by vehicles

which are still on the road at age x. In order to get miles per year for

1 The ORFES sampling frame included only vehicles owned and operated by

private individuals. Fleet vehicles such as business fleets, rental fleets,

police fleets, taxi fleets, government fleets, etc., were not sampled due to

the operational constraints of collecting reliable data on these vehicles,

as explained in the report.

219
the average vehicle in the U.S. population, these numbers must be

multiplied by the probability than a given vehicle will still be on the

road, or survive to, age x.

Tables D-1 and D-2 contain the vehicle travel data adjusted as

described above, that were used to develop the estimates of energy reduction

and dollar equivalent values in this report, for cars and trucks,

respectively. The second columns of each table are a reproduction of the

last column of Table 3-10 from Chapter 3 with the following two exceptions:

(1) Rows 1-6 of Table D-1 have been revised to incorporate

annual travel by fleet vehicles. The bases for these

estimates are that fleet vehicles number about 10,000,0002,

3

travel an average of 24,000 miles per vehicle, per year; and

have a total life-span of approximately six years.A

2 "Transportation Energy Data Book," Edition 7, Op. Cit.

3 "Characteristics of Automotive Fleets in the United States, Shonka, Op. Cit,

4 Shonka, Op. Cit., gives 2.5 years as the average age of fleet cars at the

time they are resold. Since some vehicles will be replaced earlier than

this, and some later, 6 years is taken as the maximum time a fleet car will

remain in a fleet status.

220
TABLE D-1

ESTIMATED VEHICLE MILES, LIFETIME PASSENGER CARS

Vehicle

Age

Years

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Vehicle

Miles

Traveled!./

15,700

• 14,040

13,550

11,028

9,468

8,483

4,485

3,885

3,427

3,066

2,773

2,532

2,329

2,156

2,007

1,878

1,764

1,663

1,573

1,493

Vehicle

Survival

Probability**/

1.000

.993

.982

.964

.935

.892

.831

.753

.662

.568

.476

.394

.323

.263

.213

.172

.139

.112

.090

.073

Vehicle Miles

Traveled, Lifetime,

Average Vehicle

15,700

13,942

13,306

10,631

8,853

7,567

3,727

2,925

2,269

1,741

1 ,320

998

752

567

427

323

245

186

142

109

TOTAL 85,730

—/ From Table 3-10 of Chapter 3, adjusted to incorporate fleet vehicle

travel, as described in accompanying text.

b/ Source: "Scrappage and Survival Rates of Passenger Cars and Trucks in

1970-1982 ," P. Hu", Transportation Energy Group, Oak Ridge National

Laboratory, August 10, 1983.

221
TABLE D-2

ESTIMATED VEHICLE MILES, LIFETIME LIGHT TRUCKS

Vehicle

Age

Years

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Vehicle

Miles

Traveled^'

15,470

13,260

12,608

9,250

7,174

5,862

4,956

4,293

3,427

3,066

2,773

2,532

2,329

2,156

2,007

1,878

1,764

1,663

1,573

1,493 *

Vehicle

Survival

Probability*5/

1.000

.991

.979

.963

.943

.918

.888

.852

.810

.763

.712

.658

.603

.548

.495

.444

.397

.353

.313

.277

Vehicle Miles

Traveled, Lifetime,

Average Vehicle

15,470

13,141

12,343

8,908

6,765

5,381

4,401

3,658

2,776

2,339

1,974

1,666

1,404

1,181

993

834

700

587

492

414

TOTAL 85,427

— From Table 3-10 of Chapter 3, adjusted to incorporate fleet/business

vehicle travel, as described in accompanying text.

— Source: "Scrappage and Survival Rates of Passenger Cars and Trucks in

1970-1982 ," P. Hu, Transportation Energy Group, Oak Ridge National

Laboratory, August 10, 1983.

222
(2) Rows 1-8 of Table D-2 have been revised to incorporate annual

travel for light trucks operating in a fleet environment or

read for business purposes. The bases for these estimates

are that fleet/business5 trucks represent approximately

one-half of the total light truck population6; travel

approximately 21 percent more miles annually, than

private-use trucks, and have a total lifespan of

approximately 8 years.'

The third columns of Tables D-1 and 0-2 contain the vehicle

survival probability estimates.^ The last column of each table is the

estimated yearly travel for the average vehicle and is merely the product of

the annual miles traveled (column 2) and the probability that the vehicle

will survive to age x (column 3). The sum of column 4 represents the

estimated total lifetime travel for the average vehicle, 85,730 miles, and

85,427 miles, for cars and trucks respectively.

5 49.1 percent of total pickup trucks are classified as having vehicle and

operational characteristics other than for personal transportation (i.e.,

mining, construction, utilities, etc.) Sources: 1972 Census of

Transportation, Volume II, Truck Inventory and Use Survey, U.S. Department

of Commerce, issued March 1974; "Projection of Light Truck Population Year

2025," Oak Ridge National Laboratory, ORNL/Sub-78/14285/1 Special, October

1978.

6 Average annual mileage for pickup trucks used for fleet business purpose

= 11,945 versus 9,900 for pickup trucks used for personal transportation

((11,945-9,90O)/9,900 = 21 percent). Source: 1972 Census of

Transportation, Op. Cit.

7 Available data on survival rates show trucks to have a somewhat longer

lifespan than cars; hence 8 years is taken as the maximum time a truck will

remain in a fleet/business status. Source: "Scrappage and Survival Rates

in Passenger Cars and Truck in 1970-1972, P. Hu, Transportation Energy

Group, Oak Ridge National Laboratory, August 10, 1983.

8 "Scrappage and Survival Rates in Passenger Cars and Trucks in 1970-1982,"

Op. Cit.

223
FUEL REDUCTION ESTIMATES

In order to estimate per vehicle lifetime reduction in fuel use

for a given model year, say 1978 passenger cars, it is merely necessary to

take the product of the total estimated lifetime mileage (from column 4,

Table D-1) and the per vehicle reduction in fuel use, in gallons of fuel per

mile driven versus the 1977 models (as computed in Chapter 2). For total

model year reduction (i.e., all vehicles sold), the per vehicle reduction is

simply multiplied by the total number of vehicles sold in the given model

year.

EQUIVALENT DOLLAR VALUE OF REDUCTION IN ENERGY USE

In order to estimate dollar equivalent value of the reduced fuel

consumption, it is necessary to have estimates of the cost of gasoline in

addition to the estimates of vehicle miles traveled and the per vehicle

reduction in fuel consumption in fuel per unit of travel for the study

vehicle over the baseline vehicle.

Since annual vehicle travel varies with vehicle age (specifically,

the survey data from Chapter 3 shows a distinct decline in the rate of

travel as vehicle age increases, with a large proportion of total lifetime

travel occurring in the early years of vehicle life), and since the real

price of gasoline is projected to increase over time, it is therefore

necessary to estimate dollar value per each year of vehicle life. Finally,

224
since a portion of the reduction in fuel use will occur in future years, it

is customary to discount such values to arrive at their present estimated

value.

For each vehicle of a given model year, the following formula was

used to determine the estimated, lifetime dollar equivalent of reduced fuel

consumption:

20

\ \

D

(vehlcle)j - > [(VMDi P(S)j FSj CL D^ (1)

i = 1

where,

(VMT)^ a average annual vehicle miles traveled for avehicle of age i,

from columns of Tables D-1 and D-2. Twenty years is taken

as the maximum age that a vehicle can attain.9

P(S)i = probability that a vehicle will survive to age i, from

column 3, Tables D-1 and D-2.

9 P. Hu, "Scrappage and Survival Rates in Passenger Cars and Trucks in

1970-1982," Op. Cit.

225
per vehicle reduction in fuel consumption in gallons per mile

driven, for vehicle of model year j.

estimated cost, in dollars, per gallon of fuel for year i,

from Table D-3.

discount factor for year i (to arrive at present value of

future reductions), from Table 0-4.

The total dollar value for a given model year, j, is simply the product of

the per vehicle dollar value from equation (1) and the total number of

vehicles sold in model year j, or

D(model year)j = N j D(vehicle)j

The future cost of fuel (gasoline), Table D-3, is based on data

from the Department of Energy.

All dollar values of reduced energy consumed are expressed in

terms of 1984 dollars. A discount rate of 10 percent10 has ben used to

estimate the present (1984) value of fuel reductions that will accrue in

future years. For reductions in years prior to 1984, a discount factor of

1.0 has been used since these represent historic values having already

occurred and hence not subject to future uncertainties. Table D-4 lists the

discount factors used.

10 OMB Circular No. A-94, March 27, 1972.

226
TABLE D-3

ESTIMATED AVERAGE PRICE OF UNLEADED GASOLINE, 1984 DOLLARS

Year

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

Price

(Dollars/Gallon)

$1,234

.558

.574

.396

.33

.25 :

1,,19

1.16

1.16

1.19

1.21

1.23

1.29

1.35

1.41

1.47

1.52

1.56

1.60

1.64

1.68

1.73

1.77

Sources: "Transportation Energy Data Book: Edition 7, Oak Ridge

Laboratory, ORNL-6050, Date of Issue - June 1984." (Source of

data on current year price of unleaded gasoline for years

1978-1982.)

"Economic Report of the President, Transmitted to the Congress,

February 1985." (Source of price deflator data for adjusting

1978-1982 gasoline prices to constant 1984 dollars).

Price data for 1983-1984 adapted from estimates made by NHTSA for

use in regulatory impact analyses of the 1986 CAFE standards.

Projections for 1985-1984 were adapted from the U.S. Department

of Energy (DOE) Middle World Oil Price Case, Gasoline Price Projections for the Transportation Section in "Annual Energy Outlook, 1984," Energy Information Administration, D0E/EIA-9383(84),

January 1985. Projections for 1995-2001 are DOE's "reference

case projections," in "Energy Projections to the Year 2010, A

Technical Report in Support of the National Energy Policy Plan,"

draft report, April 2, 1985. NHTSA adjusted the projections

slightly to include only the price of unleaded gasoline; some

values were interpolated.

227
TABLE D-4

DISCOUNT FACTORS FOR ESTIMATING PRESENT VALUE (1984 DOLLARS)

OF FUTURE REDUCTION IN FUEL CONSUMPTION

YEAR OF REDUCTION

1979

1980

1981

1982

1983

1984'

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

, 1999

2000

2001

DISCOUNT FACTORS

1

1

1

1

1

1

.000

.000

.000

.000

.000

.000

.9091

.8264

.7513

.6830

.6209

.5645

.5132

.4665

.4241

.3855

.3505

.3186

.2897

.2633

.2394

.2176 '

.1978 '

For discount rate = 10 percent. Note that a factor of 1.0 is used for

years 1979-1984 since the cost of fuel (Table D-3) for each of these years

is in terms of 1984 dollars. The years 1979-1983 represent "historic"

prices that have already occurred. They have been updated to 1984 dollars

as explained in Table D-3. If this study had also estimated costs of the

Federal standards (in addition to benefits), such costs would also have been

updated to 1984 from the years in which the costs were incurred, employing

the same price adjustment factors as used here for benefits (i.e., reduced

fuel consumption).

228