CBO

A

S T U D Y

Reducing Gasoline Consumption:

Three Policy Options

1RYHPEHU 

The Congress of the United States ■ Congressional Budget Office 
Notes

Numbers in the text and tables of this report may not add up to totals because of rounding.

Unless otherwise indicated, all years referred to are calendar years.
Preface

6everal Members of Congress and public interest groups have recently proposed policies that would reduce gasoline consumption in the United States. Such proposals stem primarily from a desire to enhance the nation’s energy security and to decrease its emissions of

carbon dioxide, a key greenhouse gas that affects the Earth’s climate. This Congressional Budget Office (CBO) study—prepared at the request of the Senate Committee on Environment

and Public Works—compares three methods of reducing gasoline consumption: increasing

the corporate average fuel economy (CAFE) standards that govern passenger vehicles, raising

the federal tax on gasoline, and setting a limit on carbon emissions from gasoline combustion

and requiring gasoline producers to hold allowances for those emissions (a policy known as a

cap-and-trade program).

The study weighs the relative merits of those policies against several major criteria: whether

they would minimize costs to producers and consumers; how reliably they would achieve a

given reduction in gasoline use; their implications for automobile safety; and their effects on

such factors as traffic congestion, requirements for highway construction, and emissions of air

pollutants other than carbon dioxide. In addition, the analysis examines two more policy implications that lawmakers may be concerned about: the impact on people at different income

levels and in different regions, and the effects on federal revenue. In keeping with CBO’s mandate to provide objective, impartial analysis, this report makes no recommendations.

The study was written by Terry Dinan and David Austin of CBO’s Microeconomic and

Financial Studies Division, which is directed by Roger Hitchner. Robert Dennis, Barbara

Edwards, Arlene Holen, Mark Lasky, Deborah Lucas, John Peterson, and Tom Woodward of

CBO provided valuable comments, as did Haynes Goddard of the University of Ohio at

Cincinnati and Margaret Walls of Resources for the Future. 

Christian Spoor edited the study, and Christine Bogusz proofread it. Angela McCollough and

Cecil McPherson produced initial versions of the tables and figures, Kathryn Winstead prepared the study for publication, and Annette Kalicki prepared the electronic versions for

CBO’s Web site.

Dan L. Crippen

Director

November 2002

This study and other CBO publications

are available at CBO’s Web site:

www.cbo.gov













CONTENTS

Summary vii

Introduction 1

The Rationale for Reducing Gasoline Consumption 1

A Brief History of the Three Policy Options 2

The Evaluation Criteria Used in This Study 6

Cost-Effectiveness 9

The Cost-Effectiveness of Raising CAFE Standards 10

The Cost-Effectiveness of Raising the Gasoline Tax 15

The Cost-Effectiveness of Creating a Cap-and-Trade

Program 17

Predictability of Gasoline Reductions 19

CAFE Standards 19

A Gasoline Tax and a Cap-and-Trade Program 20

Effects on Safety 21

CAFE Standards 21

A Gasoline Tax and a Cap-and-Trade Program 24

Effects on Other External Costs Related to Driving 25

Emissions of Regulated Air Pollutants 25

Congestion 26

Highway Construction and Maintenance 27

Other Policy Implications: Distributional and

Revenue Effects 29

Distributional Effects 29

Effects on Federal Revenue 34
vi REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

Tables

1. Average Characteristics of New Cars, Model Years 1978-2000 4

2. Estimated Burden of Gasoline Spending on Households 30

3. Revenue Effects of a 15-Cent Increase in the Federal

Gasoline Tax 35

Figures

1. Vehicles’ Average Fuel Economy Compared with CAFE

Standards, Model Years 1978-2000 3

2. Total State and Local Gasoline Taxes, End of 2001 5

3. Gasoline Prices and Federal Gasoline Taxes, 1950-2000 6

4. Fatality Rates for Cars and Light Trucks, 1975-2000 22

5. Annual Cost to Households in Different Regions from

a 4.3-Cent Rise in the Federal Gasoline Tax 33

6. Annual Cost to Households in Different Regions from

a 4.3-Cent Rise in the Federal Gasoline Tax, as a Share

of Household Income 34

Boxes

1. Making CAFE Standards More Cost-Effective by

Improving Their Design 12

2. Is the Market for Fuel Economy in New Vehicles Efficient? 16

3. The Effect of Price Changes on Gasoline Consumption 17

4. Changing the Design of CAFE Standards to Improve

Auto Safety 23
Summary

/awmakers concerned about the United States’

dependence on foreign oil and its emissions of carbon dioxide—a key greenhouse gas—have proposed raising the

corporate average fuel economy (CAFE) standards that

govern cars and light-duty trucks. Improving the fuel

efficiency of vehicles would reduce gasoline consumption.

Another way to lower gasoline consumption is to raise the

price of gasoline. Lawmakers could do that directly by

increasing the federal tax on gasoline. They could also do

it indirectly by setting a limit on total carbon emissions

from gasoline combustion and requiring gasoline producers to hold rights (or allowances) for those emissions,

which they could buy and sell among themselves after an

initial allocation. That policy is known as a cap-and-trade

program.

This study weighs the relative merits of tightening CAFE

standards, raising the federal gasoline tax, and creating

a cap-and-trade program against several major criteria:

• Cost-Effectiveness. Reducing gasoline consumption

would impose costs (both monetary and nonmonetary) on various producers and consumers. A costeffective policy would keep those costs to a minimum.

• Predictability of Gasoline Savings. How reliably would

the policy bring about the desired reduction in gasoline consumption?

• Effects on Safety. How would the policy alter the number and severity of traffic accidents?

• Effects on Other External Costs Related to Driving. Reducing gasoline consumption would affect not only

the United States’ energy security and carbon emissions but other driving-related external costs (ones

whose full weight is borne by society at large rather

than by an individual). Those external costs include

traffic congestion, the need for highway construction

and maintenance, and emissions of air pollutants besides carbon dioxide.

In addition to those factors, the three policy options

would have other implications that policymakers may

care about—such as their effects on people at different

income levels and in different parts of the country and

their impact on the amount of revenue collected by the

federal government.

Details of the Three Policy Options

Significant decreases in U.S. gasoline consumption could

lead to measurable declines in both the nation’s dependence on oil and its carbon emissions. Gasoline use by

motor vehicles accounts for about 43 percent of U.S. oil

consumption and about 11 percent of world oil consumption. It also accounts for 20 percent of U.S. emissions of carbon dioxide.

The methods to produce those declines that are examined

in this study are not new concepts. Fuel economy standards have been in place since 1978; the federal government has taxed gasoline since 1932; and cap-and-trade

programs have been used to address environmental problems for many years.

CAFE Standards

Under current CAFE standards, each automaker’s output

is divided into three fleets: imported passenger cars, domestically produced passenger cars, and light trucks
viii REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

(which include pickup trucks, minivans, and sport utility

vehicles). To comply, a manufacturer must ensure that

the average fuel efficiency of each of its fleets equals or

exceeds the applicable CAFE standard. Today, those standards are 27.5 miles per gallon (MPG) for domestic or

imported cars and 20.7 MPG for light trucks. (Vehicles

weighing more than 8,500 pounds are exempt from

CAFE requirements.) Producers must pay a penalty of

$5.50 per vehicle for every 0.1 MPG that their fleet average falls below the relevant standard. 

Gasoline Taxes

In 1932, the federal government levied a tax on gasoline

of 1 cent per gallon—about 6 percent of the price of gasoline at that time—as a way to raise revenue. Since then,

the tax rate has gradually increased; it now stands at

18.4 cents per gallon. 

State and local governments also tax gasoline consumption. Currently, the average tax paid on a gallon of gasoline in the United States is about 41 cents—or roughly

27 percent of the price (assuming an average retail price

of $1.50). Those 41 cents of tax include average state and

local taxes of 22.6 cents.

Today, revenue from the federal gasoline tax (as well as

from taxes on diesel, gasohol, and other special fuels) goes

into the budget’s Highway Trust Fund. That fund was

created in the mid-1950s mainly to provide a dependable

source of financing for the nation’s Interstate highways.

Since the early 1980s, revenues in the Highway Trust

Fund have also been used to pay for mass transit.

Cap-and-Trade Programs

The concept of trading pollution rights (what this study

calls emission allowances) was first introduced in the

academic literature in 1968. Since then, the federal government has used trading programs to achieve several environmental goals, such as reducing emissions of sulfur

dioxide (which cause acid rain), decreasing the lead content of gasoline, and phasing out the use of ozonedepleting chemicals.

Under the cap-and-trade program envisioned in this

study, the government would set a limit on total carbon

emissions resulting from gasoline combustion and issue

the number of allowances corresponding to that limit.

Gasoline producers and importers would be required to

hold allowances for the carbon emissions that would

result from the gasoline they sell in the United States. The

government could auction off the allowances to gasoline

companies or distribute them for free. Either way, after

the initial allocation, firms would be allowed to buy and

sell allowances among themselves. Holding those allowances would become a cost of doing business for gasoline

companies, which would lead to higher prices at the gas

pump. 

Cost-Effectiveness

Policies that produced meaningful reductions in gasoline

consumption would entail costs for producers and consumers. The reason is that such policies would compel producers and consumers to undertake gasoline-saving activities that they would not have found it in their best

interests to pursue otherwise. The costs to producers

would take the form of lower profits, and the costs to

consumers would take the form of reductions in their

well-being, because of both monetary costs (such as

higher prices) and nonmonetary costs (such as decreased

safety from driving a smaller, lighter car; reduced satisfaction from driving a less-powerful vehicle; or inconvenience associated with carpooling). 

Ideally, the costs of reducing gasoline use should be

weighed against the benefits (principally from fewer carbon emissions and less energy consumption). That way,

policymakers could encourage gasoline reductions as long

as the benefits of additional reductions exceeded the cost

of additional reductions. However, quantifying the costs

and benefits of gasoline reductions is difficult and is

beyond the scope of this analysis. 

A less challenging criterion is to design policies that are

“cost-effective”—in other words, that keep losses in producers’ profits and consumers’ welfare to a minimum for

any given level of gasoline savings. Automakers and

drivers could make numerous technological or behavioral

changes to use less gasoline, changes that could be combined in various ways or traded off for each other depending on their costs. Thus, policies would be most

cost-effective if they gave people the flexibility and the
SUMMARY ix

incentive to make as many of those changes as possible.

By contrast, policies that encouraged a few gas-saving

activities but not others would not produce the most costeffective reduction in gasoline consumption.

A cap-and-trade program or a well-designed increase in

the gasoline tax—for example, one that applied to all uses

of gasoline that could be reduced at a cost lower than the

tax—would be cost-effective ways to decrease gasoline

consumption. Both policies would raise the price of gasoline and thus provide an incentive for households to

undertake all measures that would lower their gasoline use

(provided that the cost of those measures was less than

the savings in gasoline spending that would result). Such

measures could include buying more-fuel-efficient vehicles, reducing their driving (for example, by carpooling

or taking public transportation), improving their vehicles’

maintenance, or driving more slowly.

Raising CAFE standards, by contrast, would not be a

cost-effective way to cut gasoline consumption because

it would not encourage all potential gas-saving activities.

By focusing solely on the fuel economy of vehicles, it

would give people no incentive to make gas-saving

changes in their driving behavior, such as carpooling. In

fact, by making vehicles more fuel efficient and thus

lowering the cost of driving, higher CAFE standards

could lead to more driving rather than less. Research suggests that a 10 percent increase in CAFE standards would

result in roughly a 2 percent increase in the number of

miles driven. That effect would reduce, though not eliminate, the gasoline savings caused by the improvement in

fuel economy.

Further, the current structure of CAFE standards could

encourage automakers to engage in strategies that would

bring them into compliance but would not increase fuel

economy—such as modifying the design of passenger cars

so they would qualify as light trucks and be subject to a

lower standard. Improvements in the design of CAFE

standards could reduce the use of such “unproductive”

compliance methods. However, improved standards

would still not provide an incentive to reduce driving.

If lawmakers’ primary objective was to lower carbon emissions rather than simply to decrease gasoline consumption, then a tax or a cap-and-trade program that covered

all sources of carbon emissions would be more costeffective than a policy that targeted only gasoline use. For

example, a tax on the carbon content of all fossil fuels or

a cap-and-trade program that applied to all sources of

carbon emissions would encourage emission reductions

in the utility sector, which accounts for 38 percent of

U.S. carbon emissions.

Predictability of Gasoline Savings

Some lawmakers might want assurance that the policy

they adopted would actually reduce gasoline consumption

by a given amount. Neither an increase in CAFE standards nor a rise in the federal gasoline tax would ensure

a specific decline in consumption. However, predicting

the gasoline savings that would result from a rise in welldesigned CAFE standards would be easier than predicting

the savings from a specific increase in the gasoline tax. If

CAFE standards were redesigned so that automakers had

no incentive to use unproductive compliance methods,

an increase in those standards would provide a fair

amount of certainty about the resulting rise in fuel efficiency. Thus, estimating gasoline savings would mainly

involve predicting increases in the number of miles

driven. By contrast, estimating the gasoline savings from

a tax increase would entail predicting increases in fuel

efficiency as well as decreases in total miles driven. 

Despite its greater uncertainty, an increase in the gasoline

tax could be modified over time to achieve a desired

reduction target. Furthermore, any given decrease in

consumption could be made at a lower cost through the

gasoline tax than through CAFE standards (as discussed

in the previous section). 

A cap-and-trade program could be constructed to reach

a specific target for gasoline use. The government would

issue the number of emission allowances that corresponded to that target level, and (assuming adequate

enforcement) only that amount of gasoline would be sold

in the United States. However, a specific target would not

limit the cost of reductions in gasoline consumption.

Alternatively, the government could set a maximum price

for allowances and agree to sell an unlimited quantity at

that price (otherwise, a fixed supply of allowances would
x REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

cause the price to rise). Such a policy would be analogous

to a gasoline tax: it would limit the cost of reducing

gasoline consumption by another gallon but would not

ensure that a given level of consumption was met.

Effects on Safety

Policy changes that lowered gasoline use could have

various effects on the safety of driving. If they led to the

production of smaller or lighter cars, they would tend to

make accidents more dangerous, but if they led to lighter

trucks, they could reduce fatalities. If policies encouraged

people to drive fewer miles, they would tend to decrease

the number of accidents. The safety implications of

CAFE standards have been particularly controversial, and

studies of the topic have produced mixed results. Virtually no research has been done on how a higher gasoline

tax or a cap-and-trade program would affect the safety of

driving. 

Recently, a special committee of the National Research

Council reviewed the empirical evidence about the safety

effects of CAFE standards. Most of the committee concluded that declines in the size and weight of cars that

have occurred since those standards took effect have led

to increased fatalities. The committee offered an alternative design for CAFE standards intended to enhance

safety. That design would discourage automakers from

reducing the weight of cars as a way to comply with fuel

economy standards while still encouraging them to reduce

the weight of light trucks.

Effects on Other External Costs

Related to Driving

The three policy options discussed in this study would

have implications for various external costs that result

from driving (costs that individuals do not always

consider when making decisions because they do not bear

the full weight of those costs). Such external costs include

not only U.S. energy security and carbon emissions but

also traffic congestion, the need for highway construction

and maintenance, and emissions of various other air

pollutants (carbon monoxide, nitrogen oxides, and volatile organic compounds—all of which, unlike carbon

dioxide, are regulated by the federal government). 

A higher gasoline tax or a cap-and-trade program would

tend to decrease congestion, road construction and maintenance, and emissions of regulated pollutants by discouraging driving. Higher CAFE standards, by contrast,

would encourage driving and thus would tend to increase

those costs—with the exception of emissions of nitrogen

oxides and volatile organic compounds. They would decline because lower gasoline consumption would reduce

the emissions of those pollutants that occur when gasoline

is produced and delivered, and such a decrease would

more than offset the rise in tailpipe emissions that would

result from increased driving.

Unless the policy changes that occurred were very large,

the impact on those other driving-related external costs

would most likely be small. In the case of traffic congestion, however, recent studies suggest that even small

changes could have significant economic costs.

Other Policy Implications

The policy options in this study are not intended specifically to alter the distribution of income in the United

States or to raise federal revenue. Nevertheless, increasing

the gasoline tax, tightening CAFE standards, or enacting

a cap-and-trade program would have distributional and

revenue effects, which policymakers might want to consider. 

Distributional Effects

The burden imposed by a policy change to reduce gasoline consumption will differ according to people’s income

level and where they live. Several researchers have looked

at how the effects of a higher gasoline tax or a cap-andtrade program for carbon emissions would vary among

U.S. households on the basis of those factors. For CAFE

standards, however, no evidence about distributional

effects is available.

Measuring the incidence (who currently bears the burden) of the federal gasoline tax is difficult because of

inaccuracies in reported data on annual incomes and a

lack of data on households’ longer-term ability to pay the

tax. Some studies indicate that a rise in the gasoline tax

would be regressive—that is, would place a heavier burden on lower-income households than on higher-income
SUMMARY xi

ones. Other research suggests that the effect would be

proportional among households in different income

categories. Regardless of the initial incidence of the tax,

the impact on some lower-income households would be

reduced if the tax increase caused a rise in government

payments (such as Social Security benefits and Supplemental Security Income payments) that are indexed to

changes in consumer prices. Those payments make up a

larger share of income for lower-income households than

for higher-income households.

Available evidence also suggests that an increase in the

gasoline tax would impose a bigger cost on people in rural

areas than in urban areas. The ultimate distributional effects of the tax increase would depend on what the federal

government did with the additional revenue. If laws

governing the use of Highway Trust Fund revenue were

changed, the government could use the additional money

to offset the distributional effects of higher gasoline

prices. 

Like a gasoline tax, a cap-and-trade program would raise

the price of gasoline. The distributional effects of that

price increase would be the same as those from an equivalent price rise resulting from a gasoline tax. If the government decided to distribute emission allowances for free,

the recipient gasoline companies (and, by extension, their

shareholders) would receive windfall profits. That outcome would tend to benefit higher-income households,

who on average receive a larger share of their income

from stocks than lower-income households do. Conversely, if the government chose to auction off the allowances, the ultimate distributional effects would depend

on how it used the resulting revenue.

Revenue Effects

Raising the gasoline tax would increase federal revenue.

Although higher prices would discourage gasoline consumption, that effect would not be large enough to offset

the additional revenue created by the higher tax rate.

With changes to current law, that revenue could be used

in myriad ways, such as reducing federal debt, offsetting

some of the distributional effects associated with higher

gasoline prices, or lowering other taxes. Using the revenue

to reduce taxes on capital and labor, for example, could

benefit the economy because those taxes discourage economic activity. 

Tightening CAFE standards would lead to a decline in

federal gasoline-tax receipts because more-fuel-efficient

vehicles would use less gasoline. The dampening effect

on tax receipts would grow over time as more vehicles

were retired and replaced by ones that met the higher

standards. 

For a cap-and-trade program, the effects on revenue

would depend on whether the government sold emission

allowances or gave them away. If the government sold

them, the effects would be similar to those of a gasoline

tax, and federal revenue (including auction proceeds and

gasoline-tax receipts) would rise. If allowances were

distributed for free, receipts from the gasoline tax would

fall, and the government would not collect any offsetting

revenue from selling allowances. 

Conclusions

Concerns about oil dependence and climate change have

caused some policymakers to propose actions that would

reduce gasoline consumption. Increasing the federal tax

on gasoline, creating a cap-and-trade program for

gasoline-related carbon emissions, or raising the CAFE

standards could bring about such a reduction, but they

would measure up differently against the various criteria

considered in this analysis. 

• A higher gasoline tax would be cost-effective in that

it would minimize the reduction in corporate profits

and consumers’ welfare that would result from lower

gasoline consumption. The reason is that a tax increase

would provide an equal incentive for producers and

consumers to undertake all possible gas-saving activities, rather than focusing on a few activities (such as

improving vehicles’ fuel economy). By discouraging

driving, a higher gasoline tax would also tend to decrease various driving-related external costs, such as

traffic congestion, the need to build and maintain

highways, and emissions of regulated vehicle pollutants. However, a tax increase would not reliably ensure a given reduction in gasoline use; it would have
xii REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

to be modified over time to achieve a desired level of

gasoline savings. Moreover, available research does not

indicate how raising the federal gasoline tax would affect the safety of driving.

Studies provide conflicting evidence about how the

cost of a higher federal gasoline tax would be distributed among households at different income levels, but

they do find that rural households would tend to see

higher cost increases than urban households would.

Regardless of how those costs were distributed, an increase in the gasoline tax would boost federal revenue.

The government could use that revenue in various

ways, which would have differing effects on the economy as well as different distributional consequences.

• A cap-and-trade program could be constructed that

would be just as cost-effective as a gasoline-tax increase

and would reduce driving-related external costs to the

same degree. Depending on how the program was

designed, however, it could differ from a tax increase

with respect to how predictably it would deliver a

specific amount of gasoline savings, its distributional

effects, and its impact on federal revenue. No research

is available on the safety implications of a cap-andtrade program.

• Raising CAFE standards would not be a particularly

cost-effective way to reduce gasoline consumption

because it would rely on improving the fuel efficiency

of passenger vehicles rather than encouraging the full

range of gas-saving activities by producers and consumers (some of which might be less expensive). Further,

by lowering the cost of operating a vehicle, higher

CAFE standards could encourage people to drive

more, which could increase congestion. In addition,

under the standards’ current design, automakers could

use unproductive compliance methods that would impose costs on producers or consumers but not reduce

gasoline consumption. An increase in CAFE standards

would offer more certainty about achieving a specific

reduction in gasoline use than a tax increase would but

less than a cap-and-trade program with a fixed cap

would. (The Congressional Budget Office is currently

analyzing the cost of lowering gasoline consumption

under alternative CAFE designs.)

The effect of CAFE standards on safety is a controversial topic. A majority of a committee formed by the

National Research Council concluded that the weight

and size reduction of cars that has accompanied CAFE

standards has led to more vehicle fatalities. The committee proposed an alternative design for the standards

that would address safety concerns.

An increase in CAFE standards would lead to lower

revenue from the federal gasoline tax. No information

is available about the possible distributional effects of

higher CAFE standards, however.

Finally, the three policies described in this study are not

mutually exclusive. For example, lawmakers could choose

both to tighten CAFE standards and to increase the

federal tax on gasoline. In fact, policies that raised the

price of gasoline (such as a higher tax or a cap-and-trade

program) would tend to lessen the burden of CAFE standards on automakers because they would increase consumers’ demand for fuel-efficient vehicles. However, the

total cost to producers and consumers of reducing gasoline consumption would be minimized by relying on

policies that raise the price of gasoline rather than policies

that require changes in fuel economy.
CHAPTER



Introduction

0embers of Congress have recently discussed

improving the fuel economy of cars and light trucks—a

subject that is likely to continue being debated in the

future. Those who support raising the corporate average

fuel economy (CAFE) standards that govern passenger

vehicles hope that doing so will lead to a decline in gasoline use. Such a decline could help achieve two policy

goals: enhancing the United States’ energy security and

reducing its emissions of carbon dioxide (the predominant

greenhouse gas that affects the Earth’s climate).

Other policy changes could decrease gasoline consumption

by raising its price. For example, lawmakers could increase

the federal tax on gasoline, which now stands at 18.4 cents

per gallon. Or they could institute a cap-and-trade

program for the carbon dioxide emissions that result when

gasoline is burned. (Those emissions are referred to here

as carbon emissions for short.) Under a cap-and-trade

program, the government would set a limit on carbon

emissions from U.S. gasoline consumption. Companies

would be required to hold rights—called allowances—for

each metric ton of carbon contained in the gasoline that

they produced or imported for domestic consumption.

Holding the allowances would become a cost of doing

business and would lead to higher prices at the gas pump.

A mandated increase in CAFE standards, a rise in the

gasoline tax, and a cap-and-trade program could achieve

the same policy goals, but they would have very different

consequences. (Although the three policy options are not

mutually exclusive, their relative merits are clearer when

the policies are considered individually.) This study compares those policy options on the basis of their costeffectiveness, the predictability with which they would

curb gasoline use, their implications for the safety of driving, and their effects on other driving-related factors, such

as congestion, highway construction, and emissions of pollutants other than carbon dioxide. In addition, the analysis

looks at those policies’ distributional effects—how their

impact would vary among regions and among people at

different income levels—and their effects on federal tax

revenues.

This study does not examine the full array of policies that

could ultimately reduce gasoline consumption. For example, the Department of Energy and the U.S. Council of

Automotive Research have announced a partnership to

promote the development of hydrogen as a primary fuel

for cars and trucks. If successful, that effort could lower

gasoline use substantially, but the results would not be

realized for many years. This study focuses on more-direct

policies that could decrease gasoline consumption within

the next two decades.

The Rationale for Reducing

Gasoline Consumption

The security of the United States’ energy supplies was a

major concern during the 1970s, when CAFE standards

were introduced. That concern is still voiced by some lawmakers today. Energy security can be measured in many

ways—for example, as the share of the nation’s total demand for energy that is met by imports, or as the military

cost of protecting oil supplies from the Persian Gulf, or

as the economic cost that is avoided when the world’s oil

supplies are not disrupted. The Congressional Budget

Office (CBO) believes that the last measure is the most

useful. Thus, it considers the most relevant benefits of
2 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

energy security to be the macroeconomic losses from

higher oil prices that are avoided when there are no political disruptions to oil supplies. Many analysts argue that

the United States would be less vulnerable to such disruptions if it used less oil. Consumption of finished motor

gasoline (which is derived from oil) accounts for about

43 percent of U.S. petroleum use—and about 11 percent

of world petroleum use.1

Reducing U.S. oil consumption could have other benefits.

Because the United States is such a large consumer, a significant drop in its demand would tend to lower the world

price of oil. If collusion by oil suppliers did not keep that

price from falling, a policy that reduced U.S. consumption

would save money not only because the nation would buy

less oil but because it would spend less on the oil it did

buy.2

Concern about climate change is another driving force

behind policymakers’ desire to decrease gasoline consumption. A recent report on CAFE standards by the National

Research Council cited that concern as the key reason to

make a policy change.3

 Scientists have known for more

than a century that rising concentrations of carbon dioxide

and other gases in the atmosphere affect the Earth’s climate. Burning a gallon of gasoline releases 8.9 kilograms

of carbon dioxide into the atmosphere.4

 Carbon emissions

make up 84 percent of the United States’ emissions of

greenhouse gases, and motor vehicles account for 20 percent of U.S. carbon emissions. 

Carbon dioxide emissions differ from several other vehicle

pollutants in that they are unregulated. For emissions of

hydrocarbons and carbon monoxide, for example, the

federal government sets a limit of so many grams per mile

driven. Vehicles must have pollution-control equipment

(and, in some states, periodic emission inspections) to

meet those limits. Consequently, gas-guzzling cars do not

emit more of those pollutants than fuel-efficient cars do,

so improvements in fuel economy would not lead directly

to decreases in those emissions. That is not the case for

carbon dioxide, however. Reductions in gasoline consumption would lead to roughly proportional reductions in carbon emissions. 

Although lowering gasoline use significantly could lessen

dependence on oil and decrease carbon emissions, it would

impose costs on the U.S. economy. A decline in gasoline

consumption would make society better off only if the

cost of achieving the decline was less than its benefits.

Ideally, the United States would lower its gasoline use as

long as the benefit of additional reductions exceeded the

cost of additional reductions. However, quantifying the

benefits and costs of lower gasoline consumption and

identifying the optimal level of reduction are beyond the

scope of this study. Instead, this analysis compares policies

on the basis of whether they would bring about a given

reduction at the lowest possible cost. 

A Brief History of the

Three Policy Options

The policies discussed in this study are not new concepts.

The federal government has used a gasoline tax to raise

revenue since 1932. Fuel economy standards have been

in place since the late 1970s. And cap-and-trade programs

have been used for years to address a variety of environmental problems.

1. Data on finished motor gasoline as a share of U.S. oil use come

from Energy Information Administration, Petroleum Supply

Annual 2001, vol. 1 (June 2002), Table 2 (available at www.eia.

doe.gov/pub/oil_gas/petroleum/data_publications/petroleum

_supply_annual/psa_volume1/current/pdf/table_02.pdf). The

United States accounts for approximately 26 percent of world

oil consumption; see Energy Information Administration, International Petroleum Monthly (August 2002), Table 2.4 (available

at www.eia.doe.gov/emeu/ipsr/t24.txt).

2. Under collusion, a cartel of oil suppliers would scale back production, artificially limiting supply in an effort to keep the price

of oil at the level that had existed before U.S. demand dropped.

Under competition, by contrast, the lowest-cost oil supplies

would be brought to market to meet the reduced demand at a

reduced price, and oil supplies that cost more to market than

the new, lower price would be idled.

3. See National Research Council, Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards (Washington,

D.C.: National Academy of Sciences, 2002), p. 8. 4. Ibid., p. 85.
CHAPTER ONE INTRODUCTION 3

1978 1982 1986 1990 1994 1998

14

16

18

20

22

24

26

28

30

32

Average Fuel Economy of New Cars

CAFE Standard for New Cars

Average Fuel Economy of New Light Trucks

CAFE Standard for New Light Trucks

0

CAFE Standards

Corporate average fuel economy standards were mandated

by the Energy Policy and Conservation Act of 1975. All

manufacturers that sell more than 10,000 vehicles in a

given year must comply with the standards. Each manufacturer’s output is divided into four categories: imported

passenger cars, domestically produced passenger cars, twowheel-drive light trucks, and four-wheel-drive light

trucks.5

 (Light trucks include pickup trucks, minivans,

and sport utility vehicles, or SUVs.) To comply, a manufacturer must ensure that the average fuel efficiency of its

vehicles in a particular category meets or exceeds the standard for that category. Imported and domestically produced cars have the same standard, but a manufacturer’s

imported and domestic fleets must comply with that limit

separately. Since 1992, manufacturers have had to meet

a combined standard for their two-wheel-drive and fourwheel-drive trucks. Vehicles that weigh more than 8,500

pounds are exempt from CAFE requirements.

Producers that fail to meet CAFE standards must pay a

penalty of $5.50 per vehicle for every 0.1 mile per gallon

(MPG) that their fleet average falls below the relevant standard. Manufacturers can use “credits”—which they earn

by producing alternative-fuel vehicles or by exceeding

CAFE standards in a given year—to determine their compliance. Credits may be carried forward or backward up

to three years.

When the CAFE requirements took effect in 1978, new

cars had to meet a standard of 18 MPG. Today’s standard

for cars is 27.5 MPG and has remained at that level since

1990 (see Figure 1). The current standard for light trucks

is 20.7 MPG. 

Over the past 15 years, the average fuel economy of new

cars and light trucks has improved little. Meanwhile, the

average horsepower of new cars has increased by more than

30 percent, and the average weight has risen by over

10 percent (see Table 1). With CAFE standards unchanged

and real prices for gasoline relatively constant (as discussed

below), recent improvements in technology have been

)LJXUH 

Vehicles’ Average Fuel Economy

Compared with CAFE Standards,

Model Years 1978-2000

(Miles per gallon)

Source: Congressional Budget Office based on data from the National Highway

Traffic Safety Administration (available at www.nhtsa.dot.gov/cars/

problems/studies/fuelecon/).

Note: Light trucks include pickup trucks, minivans, and sport utility vehicles.

aimed at adding power to vehicles, while continuing to

comply with current CAFE standards, rather than at increasing fuel economy.

Gasoline Taxes and Prices

The federal government levied its first tax on gasoline in

1932 at a rate of 1 cent per gallon—approximately 6 percent of the price of gasoline at that time. By 1950, the tax

had risen to 15 cents per gallon. Since then, it has gradually increased to 18.4 cents per gallon.6

 That tax covers

nearly all on-road uses of gasoline, except purchases by

state and local governments. Off-road commercial uses

(including farming, construction, and timber harvesting)

are exempt from the tax.

5. An automobile generally qualifies as domestically manufactured

if at least 75 percent of its cost to the manufacturer is attributable to value added in the United States or Canada.

6. Adjusted for inflation, the gasoline tax has ranged from a low of

6 cents per gallon in 1982 to a high of 19.6 cents per gallon in

1993 (measured in 1996 dollars).
4 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

7DEOH 

Average Characteristics of New Cars, Model Years 1978-2000

Model Year

Fuel Economy

(Miles per gallon)

Curb Weight

(Pounds)

Interior Space

(Cubic feet)

Engine Size

(Cubic inches)

Horsepower

per 100 Pounds

of Weight

1978 19.9 3,349 112 260 3.68

1979 20.3 3,180 110 238 3.72

1980 24.3 2,867 105 187 3.51

1981 25.9 2,883 108 182 3.43

1982 26.6 2,808 107 173 3.47

1983 26.4 2,908 109 182 3.57

1984 26.9 2,878 108 178 3.66

1985 27.6 2,867 108 177 3.84

1986 28.2 2,821 106 169 3.89

1987 28.5 2,805 109 162 3.98

1988 28.8 2,831 107 161 4.11

1989 28.4 2,879 109 163 4.24

1990 28.0 2,908 108 163 4.53

1991 28.4 2,934 108 164 4.42

1992 27.9 3,007 108 169 4.56

1993 28.4 2,971 109 164 4.62

1994 28.3 3,011 109 169 4.79

1995 28.6 3,047 109 166 4.87

1996 28.5 3,047 109 164 4.92

1997 28.7 3,071 109 164 4.95

1998 28.8 3,075 109 161 5.05

1999 28.3 3,116 110 166 5.21

2000 28.5 3,126 111 167 5.27

Source: Congressional Budget Office based on data from the National Highway Traffic Safety Administration (available at www.nhtsa.dot.gov/cars/problems/

studies/fuelecon/).

The federal government also taxes diesel, gasohol, and

other special fuels. Revenue from those taxes, the gasoline

tax, and various truck-related taxes goes into the Highway

Trust Fund. That fund was created in 1956 primarily to

ensure a dependable source of financing for the National

System of Interstate and Defense Highways. Initially, it

was used exclusively for highways, but in 1983 an account

was established to fund mass transit needs. The balance

in the Highway Trust Fund stood at $27.7 billion at the

end of fiscal year 2001. Of that amount, $20.4 billion was

directed to the highway account and $7.4 billion to the

mass transit account. Excise taxes on gasoline brought

$20.1 billion into the Highway Trust Fund in 2001.

In addition to the federal government, state and local governments tax gasoline consumption. Total state and local

taxes—including per-gallon taxes, sales taxes, and environmental fees—vary from a high of 35 cents per gallon in

New York to a low of 8 cents per gallon in Alaska (see

Figure 2). The average tax paid on a gallon of gasoline in

the United States is about 41 cents, which includes the

federal tax of 18.4 cents and average state and local taxes

of 22.6 cents.

Although the federal tax on gasoline has changed gradually, the price of gasoline (including taxes paid) has moved

much more dramatically. Nevertheless, in real terms (adjusted for inflation), the price of gasoline has been relatively stable for the past 15 years. In 2000, the nominal

price of gasoline was over five times higher than it had

been in 1950, but the real price was lower than in 1950

(see Figure 3). The real price of gasoline hit an all-time

high of $2.17 in 1981 (measured in 1996 dollars). But

it hovered between $1.20 and $1.35 in 11 of the 15 years
CHAPTER ONE INTRODUCTION 5

New York

Hawaii

Nevada

California

Connecticut

Florida

Rhode Island

Illinois

Michigan

Montana

Wisconsin

Pennsylvania

Idaho

West Virginia

Delaware

Washington

Nebraska

Utah

North Carolina

Oregon

South Dakota

Maryland

Maine

Ohio

Colorado

Minnesota

Arkansas

North Dakota

Kansas

Iowa

Massachusetts

Tennessee

Texas

Louisiana

Vermont

District of Columbia

Indiana

New Hampshire

Alabama

Arizona

Mississippi

Virginia

Missouri

New Mexico

Oklahoma

South Carolina

Kentucky

Georgia

New Jersey

Wyoming

Alaska

0 5 10 15 20 25 30 35 40

)LJXUH 

Total State and Local Gasoline Taxes, End of 2001

(Cents per gallon)

Source: Congressional Budget Office based on data from the Minnesota House of Representatives Research Department (available at www.house.leg.state.mn.us/

hrd/pubs/gastax.pdf).

Note: Numbers include state and local sales taxes on gasoline and special per-gallon fees used to fund environmental cleanup programs.
6 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

1950 1956 1962 1968 1974 1980 1986 1992 1998

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

Real Price of Gasoline

Nominal Price of Gasoline

Real Tax on Gasoline

Nominal Tax on Gasoline

)LJXUH 

Gasoline Prices and Federal

Gasoline Taxes, 1950-2000

(1996 Dollars)

Source: Congressional Budget Office based on data from the Energy Information Administration and the Federal Highway Administration

(available at www.eia.doe.gov/emeu/aer/ttt/tab0522.htm and www.

fhwa.dot.gov/ohim/hs00/fe101a.htm).

Note: Real numbers are adjusted to account for inflation.

from 1986 to 2000. That recent stability in the real price

of gasoline has contributed to consumers’ lack of interest

in fuel economy and to the trend toward larger and more

powerful vehicles.

Cap-and-Trade Programs

The concept of trading in pollution rights (what this study

calls emission allowances) first appeared in the academic

literature in 1968. Trading programs have been used to

achieve various environmental objectives, such as gradually

lowering the amount of lead in gasoline and phasing out

the use of ozone-depleting chemicals.7

The first federal trading program with a fixed cap applied

to sulfur dioxide emissions by electricity generators. That

program, which began in 1995, was designed to reduce

damage from acid rain. More recently, the Environmental

Protection Agency issued a rule that would require 22

eastern states and the District of Columbia to reduce their

emissions of nitrogen oxides, a major component of smog.

States could allow sources of nitrogen oxides within their

borders to participate in a trading program with other

sources throughout the affected region.8

Under the program envisioned here, the government

would set a cap on the total amount of carbon contained

in all of the gasoline consumed in the United States and

enforce the cap by issuing a limited number of allowances.9

The government could sell the allowances to gasoline

producers and importers or distribute them for free. After

the initial allocation, producers and importers would be

permitted to buy and sell allowances among themselves.

The Evaluation Criteria

Used in This Study

A rise in CAFE standards, an increase in the gasoline tax,

and a cap-and-trade program would differ in various ways.

This study highlights those differences by evaluating the

performance of the three policies against four main criteria:

• Cost-Effectiveness. Reducing gasoline use would impose

costs on consumers and producers. Would the policy

create incentives that would keep those costs to a minimum? 

• Predictability of Gasoline Savings. How reliably would

the policy achieve the desired decrease in gasoline consumption?

7. For an overview of a wide variety of state and federal environmental trading programs, see Robert C. Anderson and Andrew

Q. Lohof, The United States’ Experience with Economic Incentives

in Environmental Pollution Control Policy (report prepared for

the Environmental Protection Agency by the Environmental

Law Institute, August 1997).

8. For more information about that program, see Congressional

Budget Office, Factors Affecting the Relative Success of EPA’s NOx

Cap-and-Trade Program (June 1998).

9. All of the carbon in a gallon of gasoline is released when the

gasoline is burned, and no abatement equipment exists that can

reduce that amount. Thus, limiting carbon emissions from gasoline combustion would be equivalent to limiting gasoline production and use.
CHAPTER ONE INTRODUCTION 7

• Safety Effects. How would the policy affect the number

and severity of traffic accidents?

• Other Driving-Related External Costs. How would the

policy affect other external costs (ones borne by society

at large rather than by an individual) that result from

driving? Those costs include traffic congestion, the need

for highway maintenance, and emissions of vehicle pollutants other than carbon dioxide. 

Those criteria are described in detail in Chapters 2

through 5.

In addition to those effects, the three policy options would

have other implications that lawmakers may care about.

Those include: 

• Distributional Effects. How would the costs of the policy

be distributed among U.S. households at different income levels and in different parts of the country?

• Revenue Effects. How would the policy affect the amount

of revenue collected by the federal government?

Those criteria are examined in Chapter 6.

CHAPTER



Cost-Effectiveness

*asoline consumption can be reduced in many

ways—through technological improvements in the design

of vehicles as well as through a variety of behavioral

changes on the part of motorists. For example, manufacturers could increase the fuel economy of new vehicles or

produce vehicles that use alternative fuels, such as ethanol.

Consumers could purchase relatively fuel-efficient vehicles

and hasten the retirement of older, less efficient ones. They

could shift some of their driving to the most efficient car

they own, reduce the number of miles they drive (such

as by carpooling, using public transportation, or forgoing

long trips), maintain their vehicles better, or drive more

slowly.

Each of those gas-saving activities would impose costs on

the producer or consumer who undertook it. People can

be expected to make such changes voluntarily when the

benefits to them would outweigh the costs. For example,

drivers would choose more-fuel-efficient vehicles if they

anticipated that their gasoline savings would be greater

than the disadvantages that might be associated with such

vehicles (say, a higher price or less horsepower). Likewise,

manufacturers would voluntarily improve the fuel economy of their vehicles if they expected that doing so would

boost their profits.

If the federal government raised the gasoline tax, tightened

CAFE standards, or created a cap-and-trade program, it

would generate further gasoline savings by inducing producers and consumers to undertake such activities to a

greater degree than they would otherwise.1

 In all three

cases, the costs to producers would take the form of lower

profits, and the costs to consumers would take the form

of reductions in their well-being, because of both monetary

costs (such as price increases) and nonmonetary costs (such

as reduced satisfaction from driving a less-powerful vehicle

or inconvenience associated with carpooling). 

The three policy options would differ in which parties they

would affect directly and indirectly. Raising the tax would

have a direct impact on consumers of gasoline because it

would increase the amount they could save by reducing

their gasoline use. It would affect automakers and gasoline

producers indirectly by raising consumers’ demand for

fuel economy in new vehicles and lowering their demand

for gasoline. A cap-and-trade program, in contrast, would

affect gasoline producers and importers directly by requiring them to hold emission allowances. It would have an

indirect effect on gasoline consumers (who would face

higher prices) and on automobile producers (who would

see greater demand for fuel economy). Raising CAFE standards, unlike the other two policies, would have a direct

impact on automakers by requiring them to meet morestringent fuel economy standards. It would affect car buyers indirectly through changes in the vehicle characteristics

that manufacturers offered and the prices they charged.

1. Given recent gasoline prices, automakers have found it most

profitable to produce vehicles that just meet CAFE standards.

Higher standards would therefore compel automakers to sell

more-fuel-efficient vehicles than consumers want and would

impose costs on both producers and consumers. If gasoline

prices rose significantly, an increase in CAFE standards might

not impose costs, because higher gasoline prices would boost

consumers’ demand for fuel-efficient vehicles. In that case, however, the gasoline savings would have occurred even in the absence of tighter CAFE standards.
10 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

Higher CAFE standards would also affect gasoline producers indirectly by lessening the demand for gasoline.

Some proponents argue that raising CAFE standards

would not impose any costs. They contend that automakers have low-cost ways to improve fuel economy, that

the gasoline savings from those technologies would make

consumers better off, and that without increases in CAFE

standards, producers would fail to make use of those technologies. Their argument rests on the assumption either

that consumers lack information about vehicles’ fuel

efficiency (in other words, they do not know what is best

for them) or that producers lack an incentive to respond

to consumers’ preferences for fuel efficiency. (That issue

is discussed in detail later in this study; see Box 2 on

page 16.)

Most economists do not believe that either assumption

is valid. Vehicles’ current level of fuel efficiency most likely

reflects consumers’ trade-offs between fuel economy and

other characteristics that drivers want, such as vehicle size,

horsepower, and safety. The same technologies that can

be used to boost fuel economy can be used to hold fuel

economy constant while increasing vehicles’ weight, size,

or power. Thus, the fact that producers have done the latter rather than the former in recent years suggests that they

have responded to buyers’ preferences by targeting available technologies toward other features that consumers

desire. Raising CAFE standards would impose costs on

both consumers and automobile producers by forcing improvements in fuel economy that car buyers may not want.

Society would be best off if the costs of a policy to decrease

gasoline consumption were weighed against the benefits

of the decrease. In an ideal world, policymakers would

encourage reductions in gasoline use up to the point at

which the incremental cost—the cost of reducing an additional gallon of gasoline—that those reductions would

impose on producers and consumers equaled the incremental benefit that would result (from fewer carbon emissions and less energy consumption). However, quantifying

the benefits and costs of such reductions to determine that

ideal point is a difficult task and one that is beyond the

scope of this analysis.

A less demanding criterion is to make policy changes that

are “cost-effective” —in other words, that keep the decline

in producers’ profits and consumers’ welfare to a minimum for any given level of gasoline savings. The incremental cost of a gasoline-saving activity will rise as the level

of that activity grows. (For example, if automakers sought

higher and higher levels of fuel economy, the cost of

making an additional improvement in fuel economy would

increase.) Because producers and consumers have so many

methods to reduce gasoline use, which can be combined

in various ways or traded off for each other, policies would

be most cost-effective if they gave people the flexibility

to pursue as many of those methods as possible, up to the

point at which each method reached the same incremental

cost. (For instance, the total cost of decreasing gasoline

consumption could be lessened by relying more heavily

on reduced driving and less heavily on improvements in

fuel efficiency if the incremental cost for the former

activity was lower than for the latter.) By contrast, policies

that put all of their eggs in a few baskets—by encouraging

some gas-saving activities but not others—would not produce the most cost-effective reductions in gasoline use.

The Cost-Effectiveness of

Raising CAFE Standards

Increasing the stringency of CAFE standards would most

likely reduce gasoline consumption, but it would not do

so in a cost-effective way. The reason is that CAFE

standards do not directly encourage either producers or

consumers to decrease gasoline use, so they do not offer

the flexibility or the incentives for gasoline reductions to

occur at the lowest possible cost. That lack of costeffectiveness springs in part from shortcomings in the current design of CAFE standards, which would allow automakers to comply with higher standards in ways that

would not increase the average fuel economy of their

vehicles. It also springs from problems that are intrinsic

to any policy that regulates fuel economy instead of providing a direct incentive to reduce gasoline consumption.

Automakers’ Compliance Strategies

Raising CAFE standards gives manufacturers a strong

incentive to increase the average fuel economy of the vehi-
CHAPTER TWO COST-EFFECTIVENESS 11

cles they sell (because otherwise they must pay a fine).

Automakers could use five different strategies, individually

or in combination, to comply with higher standards. 

First, and most obvious, they could improve the fuel

economy of some or all of the vehicles they sell through

technological changes. One general way to boost a vehicle’s

fuel economy is to increase the overall efficiency of its

power train (the mechanism that transfers power from the

engine to the axles) in order to reduce energy losses.

Another way is to decrease the amount of energy needed

to propel the vehicle, by altering its weight, aerodynamics,

rolling resistance, or the power drain on the engine from

components such as the cooling fan and the air-conditioning compressor.2

Second, manufacturers could give consumers financial

incentives to buy their more-fuel-efficient vehicles. That

strategy, called mix shifting, involves subsidizing (through

lower prices) the sale of more-fuel-efficient vehicles and

charging a premium (through higher prices) for less-fuelefficient ones. Because there are separate standards for cars

and light trucks, mix shifting could occur within each category but not between categories. Some studies have shown

that mix shifting is more expensive than technology

improvements and that although some mix shifting takes

place, automakers have relied mainly on technological

changes to comply with CAFE standards.3

Third, manufacturers could alter the domestic content

of their vehicles. Because they must comply with separate

(though identical) standards for their domestic and imported fleets, automakers cannot use relatively fuelefficient imports to offset less efficient domestically produced vehicles. (Imported cars are typically more fuel

efficient than domestic ones because they also cater to

foreign markets, where consumers often face higher gasoline prices than in the United States.) By altering the

amount of their vehicles’ value that is produced in the

United States or Canada so that domestic cars can be

reclassified as imports, automakers could use the higher

fuel economy of their imported fleet to offset the lower

fuel economy of what would otherwise be domestic

vehicles. One researcher has concluded that such a strategy

could lower manufacturers’ compliance costs significantly,

but the extent to which they have used it is unknown.4

Fourth, automakers could alter the design of cars so that

they would be reclassified as trucks and thus face a lower

CAFE standard. Anecdotal evidence of that practice exists

(for example, Chrysler’s PT Cruiser, which can carry just

four passengers and cannot tow a trailer, qualifies as a

truck because it has a removable backseat). However, the

extent of that practice is unknown.5

Policymakers established a lower CAFE standard for light

trucks because when the standards were created, light

trucks were primarily work and cargo vehicles that needed

extra power, different gearing, and less aerodynamic designs to perform their work-related functions. At that time,

they accounted for about 20 percent of new vehicles sold.

Today, light trucks constitute nearly half of new vehicles

sold, and many of them are used almost exclusively for

personal transport rather than for work or cargo.6

2. For a detailed discussion of technologies for improving fuel

economy, see National Research Council, Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards

(Washington, D.C.: National Academy of Sciences, 2002).

3. Andrew Kleit found evidence of mix shifting in 1999 and concluded that it was a very expensive compliance strategy; see

Andrew N. Kleit, Short- and Long-Range Impacts of Increases in

the Corporate Average Fuel Economy (CAFE) Standard (Washington, D.C.: Competitive Enterprise Institute, February 7, 2002),

available at www.cei.org/pdf/2398.pdf. David Greene and

Yuehui Fan found that mix shifting had little effect on the gains

in fuel economy that occurred between 1975 and 1993; see

David L. Greene and Yuehui Fan, Transportation Energy Intensity Trends: 1972-1992, Transportation Research Record No.

1475 (Washington, D.C.: Transportation Research Board,

1995).

4. See Pinelopi Koujianou Goldberg, “The Effects of the Corporate Average Fuel Efficiency Standards in the US,” Journal of

Industrial Economics, vol. 46, no.1 (March 1998), pp. 1-33.

5. National Research Council, Effectiveness and Impact of Corporate

Average Fuel Economy (CAFE) Standards, p. 88.

6. Ibid, p. 88.
12 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

%R[ 

Making CAFE Standards More Cost-Effective by Improving Their Design

The same level of fuel efficiency that corporate average

fuel economy (CAFE) standards require today might be

achieved at a lower cost if the current CAFE program was

restructured. That program includes distinct standards

for cars and light trucks, requires automakers to comply

separately for domestic and imported cars, and makes each

company meet the standards individually rather than measuring compliance at the industry level. All three of those

features limit manufacturers’ behavior without reducing

gasoline consumption. Easing those constraints could potentially lower the costs of complying with the current

CAFE standards. 

Setting a Single Standard for All Vehicles

Reducing gasoline consumption imposes some monetary

and nonmonetary costs on producers and consumers; the

issue is how best to minimize those costs. With most automakers required to meet several standards (for domestic

cars, foreign cars, and light trucks), total costs will generally not be kept to a minimum. The reason is that the costs

of complying with separate standards tend to be unequal

at the margin (the point at which a final expenditure, price

change, or weight reduction just brings a firm into compliance). Inequalities in marginal compliance costs indicate

that the total cost of the CAFE program can be reduced

without lowering overall fuel economy.

Any given level of fuel efficiency could be achieved more

cheaply by allowing manufacturers to undercomply where

their marginal costs were highest, as long as they overcomplied by an equivalent amount (in terms of gasoline

savings) where their costs were lower. For instance, it may

be cheaper for an automaker to save “one more gallon”

of gasoline by raising the average mileage of its light trucks

somewhat than by raising the average mileage of its domestic cars slightly. Likewise, a firm might be able to increase

average mileage more cheaply for its imported vehicles

than for its domestic fleet. If a unified standard applied

to all of an automaker’s light-duty passenger vehicles—including light trucks and domestic and imported cars—

companies would be free to take advantage of such costsaving trade-offs.

Moreover, if it was appropriately designed, a unified standard would eliminate manufacturers’ incentives to use unproductive compliance methods. In other words, firms

could not reduce compliance costs by designing cars that

could be classified as trucks or by altering production practices so that cars were classified as imported instead of domestic. Further, a unified standard would not give consumers an incentive to switch from cars to trucks, since

trucks would no longer be subject to less-stringent fuel

economy requirements.

Making the transition to a single standard for all vehicles

could pose difficulties, however. A unified standard that

reflected the current average fuel economy of all new lightduty vehicles sold would benefit manufacturers that sell

mainly cars and penalize firms that sell mainly trucks. For

example, the existing car and truck standards (27.5 and

20.7 miles per gallon, respectively) and the roughly 50/50

mix of current car and truck sales imply a unified standard

of 24.1 MPG. An automaker that produced 75 percent

trucks and 25 percent cars and just met the separate car

and truck standards would have an average mileage rating

of 22.4 MPG for its total fleet. That firm would be out

of compliance under the unified standard, even though

it had been in compliance with the separate standards. In

contrast, a company that produced 75 percent cars and

25 percent trucks and also just met the separate standards

would have a combined fleet average of 25.8 MPG, which

would exceed the unified standard.

One way around that problem would be to set a separate

unified standard for each manufacturer—one that reflected

the current requirements for cars and trucks as well as the

manufacturer’s existing mix of car and truck sales. Such

a standard would not alter automakers’ compliance status.
CHAPTER TWO COST-EFFECTIVENESS 13

%R[ 

Continued

(In the above example, the first company would be required to meet a unified standard of 22.4 MPG, and the

second company would have to meet a unified standard

of 25.8 MPG.) But that design would “grandfather” lower

standards for manufacturers that now produce a relatively

large share of trucks. Alternatively, each automaker’s

standard could be adjusted annually to reflect that year’s

mix of car and truck sales. However, such an adjustment

would not eliminate companies’ incentives to use one unproductive compliance method. Specifically, manufacturers would be able to lower their overall compliance requirements by making vehicles that could be classified as

light trucks rather than as passenger cars.

Setting a Standard for the Industry as a Whole

Under a unified standard for cars and trucks, cost differences would still generally exist among automakers because

of differences in the average size and performance attributes of their vehicles and in their manufacturing costs.

One way to reduce total costs would be to lessen differences in compliance costs among companies. That could

be accomplished through fuel economy credit trading.1

Under such a trading system, the government would set

a fuel economy standard for the entire auto industry.

Manufacturers that exceeded the standard would generate

credits, which they could sell to firms that fell below the

standard. (The credits would be measured in gallons of

gasoline saved.) Each company’s compliance would be

based on the fuel economy of the vehicles it sold in a given

year, plus the number of fuel economy credits it held.

Automakers with lower marginal compliance costs could

raise their average MPG ratings above the required level

in order to generate credits to sell. Other companies could

1. Such trading was recommended in National Research Council,

Effectiveness and Impact of Corporate Average Fuel Economy (CAFE)

Standards (Washington, D.C.: National Academy of Sciences,

2002).

buy those credits to make up a shortfall in their fleets’

mileage ratings.2

 It would be cheaper for high-cost firms

to buy credits than to achieve the standard directly. (That

is roughly the same principle that underlies cap-and-trade

programs, in which sources of pollution trade emission

allowances.)

Letting overcomplying firms sell fuel economy credits to

undercomplying firms could minimize total costs to producers and consumers. However, if the industrywide

standard was a unified one covering both cars and trucks,

credit trading would transfer wealth within the auto industry from companies that now sell a majority of trucks (and

would need to buy credits under the unified standard) to

companies that now sell a majority of cars (and would have

excess credits to sell under the new standard). Of course,

credit trading could be implemented either with or without a unified standard for all vehicles.

The potential for credit trading to reduce total compliance

costs would depend on how much those costs would vary

among automakers in the absence of trading. The greater

that variation, the greater the possible savings from trading. Further, credit trading would minimize compliance

costs only if the market for credits was competitive—that

is, if no buyer or seller could influence the price of credits.

More research is needed to determine the extent to which

credit trading could actually lower the overall cost of

meeting CAFE standards. The Congressional Budget

Office is currently analyzing that issue.

2. Because some manufacturers already achieve greater fuel economy

than the current standards require, credit trading could increase

gasoline consumption if the standards themselves were not also

raised. The reason is that sales of credits by overcomplying firms

allow the buyers of the credits to undercomply by an equivalent

amount. That would let some companies expand their sales of lessfuel-efficient vehicles. Alternatively, standards could be tightened

enough to leave total gasoline consumption unchanged.
14 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

Fifth, manufacturers could make “flex-fuel” vehicles—

which can operate on ethanol as well as gasoline—as part

of their compliance strategy. The government assumes that

such vehicles will be operated on gasoline only half of the

time, and it counts only miles per gallon of gasoline for

compliance purposes. For example, a vehicle that got 20

miles per gallon when running solely on gasoline would

be classified as a vehicle with a fuel efficiency of 33 MPG

if it was also capable of running on ethanol.7

Problems with the Current Design of CAFE Standards

Raising CAFE standards would fall short of the costeffectiveness ideal in part because of the current design

of those standards. As noted above, automakers can comply with them in ways that do not lead to lower gasoline

use. Altering the manufacture or design of vehicles so they

count as imported rather than domestic or as light trucks

rather than cars neither raises the overall fuel economy

of passenger vehicles nor reduces gasoline consumption.

Producing flex-fuel cars can also achieve CAFE compliance

without decreasing gasoline use if those cars are not actually run on ethanol, as seems to be the case.8

 The lower

the price of gasoline—and hence the less that buyers want

relatively fuel-efficient cars—the more incentive manufacturers have to find ways of complying with CAFE standards that do not involve altering the fuel economy of

their vehicles and do not lead to lower gasoline consumption.

In addition, manufacturers can avoid CAFE constraints

altogether by producing vehicles that exceed 8,500

pounds. For example, the Ford Excursion, which is used

as a passenger vehicle, weighs more than 8,500 pounds

and thus is not subject to any CAFE limit. 

If higher standards caused car prices to increase more than

light-truck prices, some consumers might switch from

buying cars to buying light trucks that use more gasoline.9

Such switching would not put manufacturers out of compliance but would lead to greater gasoline consumption.

Another problem with the standards’ current design is that

since each manufacturer must meet CAFE standards for

its own fleet, the incremental cost of further improvements

in fuel economy will differ among automakers. The total

cost of improving fuel economy would be lower if manufacturers with relatively high compliance costs were

allowed to undercomply, so long as manufacturers with

relatively low costs overcomplied by the same amount (as

measured in gasoline consumption).10

Those shortcomings of the CAFE program could be

reduced by making various design modifications to the

current standards. (For more details, see Box 1 on page 12.)

Problems with Targeting Fuel Economy

Even if the previous shortcomings were addressed, raising

CAFE standards would not be cost-effective for at least

two reasons, which are intrinsic to any policy that targets

fuel economy. First, those standards do not give people

an incentive to change their driving habits in ways that

would reduce gasoline use. Instead, CAFE-induced improvements in the fuel efficiency of new vehicles would

lower the cost of driving those vehicles and could cause

their owners to drive more. Researchers generally assume

that a 10 percent decline in the fuel-related costs of driving

7. Those MPG figures account for the fact that ethanol is 15 percent gasoline; they assume that such a vehicle would get 15

MPG running on ethanol. See Richard C. Porter, Economics at

the Wheel (San Diego: Academic Press, 1999).

8. Using information from the Energy Information Administration, the National Research Council estimated that less than 1

percent of the fuel consumed by flex-fuel vehicles in 1999 was

ethanol; the rest was gasoline. See National Research Council,

Effectiveness and Impact of Corporate Average Fuel Economy

(CAFE) Standards, p. 89. Moreover, in 2000, only 113 fueling

stations in the United States offered ethanol; see Department of

Energy, Transportation Energy Data Book: Edition 21 (October

2001), Table 7-15 (available at www-cta.ornl.gov/data/tedb21/

Spreadsheets/Table7_15.xls).

9. One study suggests that consumers will respond that way, but

its results are illustrative rather than based on empirical data.

See Steven G. Thorpe, “Fuel Economy Standards, New Vehicle

Sales, and Average Fuel Efficiency,” Journal of Regulatory Economics, vol. 11 (1997), pp. 311-326. 

10. Equivalent increases or decreases in MPG ratings would not

produce equivalent changes in gasoline consumption. For example, raising fuel economy from 33 MPG to 34 MPG would save

0.09 gallons per 100 miles driven, whereas lowering fuel economy from 21 MPG to 20 MPG would increase gasoline use by

0.24 gallons per 100 miles.
CHAPTER TWO COST-EFFECTIVENESS 15

leads to about a 2 percent increase in the number of

vehicle miles driven.11

Second, an increase in CAFE standards could cause some

drivers to delay buying new vehicles and instead operate

their older, less-fuel-efficient ones longer. Such delays

would tend to occur if manufacturers complied with

higher CAFE standards by making technological changes

that raised car prices. Although all old vehicles would be

retired eventually, delaying new-car purchases would postpone the full realization of the fuel-saving benefits associated with technology improvements.12

The Cost-Effectiveness of

Raising the Gasoline Tax

A well-designed increase in the federal tax on gasoline

would give consumers a direct incentive to reduce gasoline

consumption. As a result, it would encourage them to

undertake all of the activities that could lead to lower

gasoline use. Consumers would have an incentive to drive

less, to rely more heavily on the most fuel-efficient car they

owned, to retire gas-guzzling vehicles earlier, and to buy

more-fuel-efficient vehicles. In general, people engage in

each of those activities up to the point at which the cost

of the activity equals the savings in gasoline spending that

it brings about. A higher gasoline tax would encourage

consumers to undertake more of each of those activities

by increasing the value of their gasoline savings. Thus, it

could lead to a cost-effective reduction in gasoline consumption.

Moreover, an increase in the gasoline tax would not create

incentives for manufacturers to make unproductive design

changes that would raise their fleets’ MPG ratings by reclassifying vehicles without reducing gasoline use. With

a gasoline-tax hike, sales of more-fuel-efficient vehicles

would increase (relative to sales of less-fuel-efficient ones)

and the fuel economy of vehicles would improve because

of changes in consumer demand, not because manufacturers had to meet regulatory requirements. 

To be most cost-effective, an increase in the gasoline tax

would need to be well designed in at least two ways. First,

it would have to cover all uses of gasoline that could be

reduced at a cost lower than the tax. As noted in Chapter 1, gasoline purchased by state or local governments

or for off-road commercial uses is exempt from the tax.

The extent to which such exemptions would reduce the

cost-effectiveness of a rise in the gasoline tax would depend

on the potential for gas-saving changes in the exempted

sectors. If that potential was low (in other words, gasoline

consumption in those sectors would not change under the

tax), then exempting the sectors would not significantly

limit the cost-effectiveness of the tax increase.

Second, a significant rise in the gasoline tax would have

to be matched by an equivalent rise in the tax on diesel

fuel. Otherwise, drivers might shift to diesel-powered

vehicles, lessening the effectiveness of the gasoline-tax increase. (Currently, less than 1 percent of new automobiles

sold in the United States are powered by diesel fuel.)13

Further, a tax increase would be most effective at reducing

gasoline consumption if it was perceived as permanent

and was adjusted to keep pace with inflation. If people

expected that a rise in the gasoline tax would be removed

11. Estimates of that response vary: some research suggests that a 10

percent decrease in fuel costs could lead to as much as a 4 percent rise in vehicle miles driven, whereas other studies show

little effect. Most studies find increases of between 1 percent

and 3 percent, and an estimate of 2 percent is frequently used in

empirical research. For a discussion of the estimates, see David

L. Greene, Why CAFE Worked (Oak Ridge, Tenn.: Oak Ridge

National Laboratory, November 1997). 

12. One study claims that manufacturers’ mix shifting could lead to

increased gasoline consumption. The reason is that mix shifting

could raise the total number of vehicles purchased (if buyers of

relatively fuel-efficient vehicles were more likely to increase their

purchases when prices fell than buyers of less-fuel-efficient vehicles were to decrease their purchases when prices rose). However, that study fails to account for the effect that increased sales

would have on the retirement of vehicles. If higher sales were

matched by accelerated retirements, gasoline consumption

would fall. See John E. Kwoka, “The Limits of Market-Oriented Regulatory Techniques: The Case of Automotive Fuel

Economy,” Quarterly Journal of Economics, vol. 97 (November

1983), pp. 695-704.

13. In 2000, 0.26 percent of new retail automobile sales in the

United States were of diesel-powered vehicles. See Department

of Energy, Transportation Energy Data Book: Edition 21 (October 2001), Table 7-3 (available at www-cta.ornl.gov/data/

tedb21/Spreadsheets/Table7_03.xls).
16 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

%R[ 

Is the Market for Fuel Economy in New Vehicles Efficient?

An increase in the gasoline tax would lead to the production of more-fuel-efficient vehicles only if it caused

consumers to attach a higher value to fuel economy and

if producers responded to the rise in demand for moreefficient vehicles. Some advocates of corporate average fuel

economy (CAFE) standards argue that a regulatory approach is necessary because the market for fuel economy

is not efficient—that is, consumers and producers would

not respond in those ways to a rise in the gasoline tax.1

Some proponents of CAFE standards maintain that although fuel economy is displayed on the labels of new

vehicles (in the form of miles per gallon for highway and

city driving), consumers lack the information to precisely

determine their individual savings from greater fuel economy. Those savings depend on the amount of highway versus city driving they will do, their projections of future

gasoline prices, and the discount rate (the interest rate used

to determine the present value of future benefits and costs)

that they select.

Although few consumers may make those calculations,

the fuel economy information on labels does let them

assess the relative fuel economy of vehicles. Without making actual calculations, consumers who expect higher gasoline prices in the future and who are concerned about operating costs (perhaps because they drive a great deal or

have tight budgets) will tend to value fuel economy more

1. This description of potential failures in the market for fuel economy

is based on David L. Greene, Why CAFE Worked (Oak Ridge,

Tenn.: Oak Ridge National Laboratory, November 1997), pp. 3-4.

than consumers who drive less, have larger budgets, or

expect lower gasoline prices in the future. There is little

reason to believe that a tax increase that significantly raised

gasoline prices would not increase the value that consumers attach to fuel economy. 

Another problem with the automobile market, according

to CAFE advocates, is that buyers cannot be expected to

take the time and effort to balance their preference for fuel

economy against the numerous other features they may

care about, such as size, reliability, style, and performance.

That does not mean, however, that fuel economy does not

affect vehicle choice. Fuel economy, like cargo space or

performance, is one of multiple features that influence a

buyer’s preference for one vehicle over another. Consumers would need to make trade-offs among the relative

importance of those features, but in cases in which other

features were the same, they would prefer a vehicle with

higher fuel economy. If a gasoline-tax increase caused

consumers to prefer more fuel economy, producers would

have an incentive to take that preference into account

when redesigning models.

Finally, some proponents of CAFE standards argue that

producers would be reluctant to make design changes that

would boost fuel economy, because if they made a design

mistake, they could lose a significant share of the market

for a single vehicle model. Conversely, producers could

gain market share by choosing designs that better reflected

consumers’ preferences for all features, including fuel

economy. There is little reason to believe that automakers

would be more reluctant to meet consumers’ demand for

fuel economy than for any other feature.

or would fall over time because of inflation, they would

have less reason to buy more-fuel-efficient vehicles. 

Some advocates of CAFE standards have argued that

failures in the automobile market would prevent an

increase in the gasoline tax from leading to improvements

in the fuel economy of vehicles (see Box 2). However, most

analysts agree that a gasoline-tax increase could be effective

in boosting fuel efficiency.

In addition, studies have found that consumers respond

to higher gasoline prices by reducing their gasoline consumption, particularly in the long run. (For more details

of those studies, see Box 3.) In the short run, consumers

may respond to higher prices mainly by driving less (for

example, by carpooling or using public transportation)

or by switching some of their driving to the most fuelefficient vehicle they own. In the long run, consumers can

make more-drastic changes to reduce their gasoline use.
CHAPTER TWO COST-EFFECTIVENESS 17

%R[ 

The Effect of Price Changes on Gasoline Consumption

Consumers’ responsiveness to price changes is measured

in the form of a “price elasticity.” That elasticity indicates

the extent to which a 1 percent increase in price would

affect the demand for a good or service (measured as a percentage change in the quantity sold).

Empirical estimates of price elasticities for gasoline vary

greatly, in part because they are sensitive to the type of

model used to estimate them. A 1991 survey analyzed

97 price-elasticity estimates for gasoline.1

 It defined 18

different categories of models and estimated the average

short-run and long-run price elasticity for the types of

models most appropriate for measuring those elasticities.

The authors found an average short-run elasticity of -0.26

and an average long-run elasticity of -0.86.2

 Based on those

estimates, a 15-cent increase in the tax on gasoline (or a

10 percent increase in price, assuming a price of $1.50

per gallon) would cause a 2.6 percent decrease in the

amount of gasoline used by passenger vehicles in the short

run and an 8.6 percent decrease in the long run. An

1. Carol Dahl and Thomas Sterner, “Analyzing Gasoline Demand

Elasticities: A Survey,” Energy Economics (July 1991).

2. Seven different categories of models were found to be appropriate

for measuring short-run and long-run elasticities. The average

elasticity estimates for the categories considered appropriate for measuring the short-run price elasticity ranged from -0.22 to -0.31.

The average estimates for categories appropriate for long-run

elasticities ranged from -0.80 to -1.01.

 equivalent decline in gasoline consumption would result

from increasing the stringency of corporate average fuel

economy standards by roughly 10 percent.3

Consumers’ responsiveness to changes in gasoline prices

could alter over time because of numerous factors, such

as changes in average income, options for public transit,

and the availability of technologies for improving fuel

economy. Some (though not all) more-recent studies have

estimated lower long-run price elasticities. Based on a review of those studies, the Department of Energy suggests

a long-run price elasticity of -0.38—implying that a 15-

cent rise in the gasoline tax would eventually cause a 3.8

percent decline in the amount of gasoline used by passenger vehicles.4

 Measuring price elasticities is a difficult task,

however, and the elasticities discussed here should be

viewed only as rough estimates.

3. That estimate assumes that a 10 percent increase in fuel economy

would result in a 2 percent increase in vehicle miles traveled. It

also assumes that the increase in CAFE stringency would not cause

consumers to switch from cars to trucks and would not cause

manufacturers to shift vehicle production from domestic cars to

light trucks and imported cars.

4. Department of Energy, Office of Policy and International Affairs,

Policies and Measures for Reducing Energy Related Greenhouse Gas

Emissions: Lessons From Recent Literature, DOE/PO-0047 (July

1996).

For instance, they can trade in their vehicles for models

with greater fuel economy or choose to live closer to their

work.

The Cost-Effectiveness of

Creating a Cap-and-Trade Program

Like a tax increase, a cap-and-trade program for gasolinerelated carbon emissions would reduce gasoline consumption in a cost-effective way. Companies would have to buy

emission allowances in order to continue producing or

importing gasoline, which most likely would lead to higher

prices at the pump. By raising the price of gasoline, a capand-trade program would give people an incentive to engage in all possible gas-saving activities, including buying

more-fuel-efficient vehicles as well as changing their driving habits. 

If the main objective of the cap-and-trade program was

to decrease carbon emissions, the same level of emission

reductions could be achieved at a lower cost by extending

the program as broadly as possible—in other words, by

making it apply to all sources of carbon emissions throughout the economy, not just the combustion of gasoline.
18 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

Under one type of broad program (an “upstream” program), all producers and importers of oil, coal, and natural

gas would be required to hold allowances based on the

carbon content of their fuel—that is, the carbon emitted

when the fuel is burned.14

The cap on carbon emissions would limit the production

of carbon-based fossil fuels and would cause the price of

those fuels to rise—with price increases reflecting each

fuel’s allowance requirements and, hence, its carbon content.15 Those price increases would raise companies’ and

consumers’ costs, encouraging them to decrease their use

of fossil fuels and energy-intensive goods and services. As

a result, households and businesses throughout the economy would have an incentive to reduce all forms of carbon

consumption and thus carbon emissions. (For example,

utilities, which account for 38 percent of U.S. carbon

emissions, would have an incentive to rely less on coal,

which is the most carbon-intensive fossil fuel.) In short,

an upstream cap-and-trade program would create an

economywide incentive to decrease carbon emissions and

would ensure that reductions were made at the lowest

possible cost. 

In contrast, a cap-and-trade program that covered only

producers and importers of gasoline would confine incentives for cutting carbon emissions to the gasolineconsuming sector—which accounts for just 20 percent

of U.S. carbon emissions. Such a system would not encourage potentially lower-cost reductions that might have

been made outside that sector.

Similarly, raising the gasoline tax would reduce carbon

emissions from gasoline consumption but would not encourage reductions in other sectors. Alternatively, levying

a tax on the carbon content of all fossil fuels—much like

enacting an upstream cap-and-trade program—would

create an incentive for carbon reductions throughout the

economy.

14. Requiring that companies hold an allowance for each ton of

carbon introduced into the economy through production or

importation of fossil fuels is equivalent to requiring an allowance

for each ton of carbon emitted into the atmosphere. That is

because there is no economically viable method (such as scrubbing emissions from smokestacks) for reducing the amount of

carbon emissions per unit of fuel burned.

15. For example, the carbon released per million British thermal

units (MBTU) of coal is 1.8 times the amount released per

MBTU of natural gas.
CHAPTER



Predictability of Gasoline Reductions

,n adopting a policy to decrease gasoline consumption,

lawmakers might want assurance that the policy would

achieve the reductions intended. However, neither raising

corporate average fuel economy standards nor increasing

the federal gasoline tax would ensure a given decline in

gasoline use. In both cases, the ultimate decrease in consumption would depend, at least in part, on how consumers and producers responded to the policy change. Between those two changes, however, the uncertainty about

the resulting gasoline reduction would most likely be

greater for an increase in the gasoline tax than for an increase in well-designed CAFE standards. For a cap-andtrade program, the predictability of gasoline savings would

depend on the design of the program.

CAFE Standards

Under the current design of the CAFE standards, estimating how much gasoline use would decline in the long run

because of a given increase in the standards would require

estimating the size of several changes in producers’ and

consumers’ behavior. Particularly important are the extent

to which:

• Manufacturers would comply with higher standards

by using unproductive strategies that would not increase

the overall fuel efficiency of the vehicles they sold,

• Price changes caused by the higher standards would

cause consumers to switch from cars to light trucks,

• CAFE-induced price changes would cause consumers

to buy vehicles that exceed the weight limit that the

standards apply to (8,500 pounds), and

• Lower operating costs would cause buyers of new vehicles to drive more miles.1

If the CAFE standards were redesigned so that automakers

had to meet a single, unified requirement for their entire

fleet—including trucks, cars, and foreign and domestic

vehicles—then producers and consumers would not have

an incentive to engage in the first two activities (see Box 1

on page 12). In that case, raising the CAFE standards

would be expected to produce a corresponding increase

in the fuel economy of cars and light trucks (assuming that

the penalty for noncompliance was high enough that

manufacturers would meet the standards).

Some of the potential gasoline savings from a rise in fleetwide fuel economy would be offset by increases in driving.

However, that offset would probably be limited to about

20 percent. (Estimates vary, but most lie between 10 percent and 30 percent, as noted in Chapter 2.)2

 Thus, unless

higher CAFE standards caused consumers to buy vehicles

weighing more than 8,500 pounds, the gasoline savings

associated with an increase in well-designed CAFE standards would be relatively easy to predict.

1. Increases in the stringency of CAFE standards could also slow

the retirement of existing vehicles. However, that effect would

not alter the long-run gasoline savings associated with raising

CAFE standards, which are the savings that would occur once

the existing stock was replaced with vehicles subject to the new

standards. 

2. See note 11 in Chapter 2.
20 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

A Gasoline Tax and a

Cap-and-Trade Program

An increase in the gasoline tax would not ensure a specific

decline in gasoline use, nor—unlike improved CAFE standards—would it cause a specific increase in fuel economy.

Thus, estimating the gasoline savings that would result

from a particular tax increase would require estimating

changes in fleetwide fuel economy (which depend on

changes in consumer demand) as well as changes in the

number of vehicle miles traveled. Price elasticities provide

estimates of the expected change in gasoline consumption

for a given price increase (see Box 3 on page 17), but such

estimates are rough ones. Despite its uncertainty, however,

a gasoline tax could be adjusted over time to meet a

specific reduction target.

A cap-and-trade program could be designed to ensure that

a given target for gasoline consumption was reached.

Because the amount of carbon in gasoline is fixed, a limit

on carbon emissions would essentially curtail the production of gasoline. The government could set an overall target and issue the number of emission allowances that corresponded to the target level. However, such a policy

would not limit the cost of reductions in gasoline consumption. In other words, gasoline use would be reduced

to the target level even if the cost of making reductions

became very high as the target was approached. (Low-cost

methods would be used first, leaving successively highercost methods as the amount of reductions was increased.)

Alternatively, the government could set a ceiling on the

price of allowances by agreeing to sell an unlimited quantity of them at that price (otherwise, the fixed supply of

allowances would cause the price to rise). Setting a maximum price for allowances would limit reductions in carbon consumption to ones that cost less than that price.

It would not, however, ensure that the target was met. If,

through trading, the allowance price rose to the ceiling,

the government would sell additional allowances at that

price, and the amount of gasoline consumed would exceed

the target level. In that case, the cap-and-trade program

would be analogous to a gasoline tax, with the tax rate

equal to the ceiling price for allowances.
CHAPTER



Effects on Safety

3olicy changes that reduce gasoline consumption

could have varying effects on the safety of driving. Policies

that led to smaller or lighter cars would tend to make accidents more dangerous, whereas policies that led to lighter

trucks could reduce fatalities. Policies that encouraged

people to drive fewer miles would tend to lower the number of accidents. 

Studies of the safety implications of corporate average fuel

economy standards have produced mixed results. Virtually

no research has been done on the safety implications of

a higher gasoline tax or a cap-and-trade program for carbon emissions.

CAFE Standards

The effect of CAFE standards on driving safety has been

a much debated—and highly contentious—issue. Numerous studies have examined the topic and reached varying

conclusions. A recent report by the Committee on the

Effectiveness and Impact of Corporate Average Fuel

Economy Standards, formed by the National Research

Council, discussed that controversy and weighed the

existing empirical evidence.1

 This section draws heavily

on the committee's discussion and analysis.

During the first five years that CAFE standards were in

effect, the weight and size of new cars declined rapidly:

average weight fell by 800 pounds, and average wheelbase

decreased by seven inches. Light-duty trucks also declined

in weight, though to a lesser extent. In the past decade,

both cars and light trucks have grown again. Today, cars

are about 600 pounds lighter than they were in 1976, on

average, and light trucks are about 30 pounds heavier. 

Changes in the weight and size of cars and light-duty

trucks can be expected to have different effects on safety.

The occupants of lighter vehicles experience greater force

in collisions with other vehicles or with fixed objects. In

addition, smaller vehicles offer smaller crush zones and

less interior space for restraint systems to operate effectively. Thus, decreasing the weight and size of cars would

lead to a higher number of fatalities. Theoretically, the

same would be true for trucks, but the increased risk to

occupants of lighter trucks during collisions is offset by

the reduced risk to occupants of other (usually much

lighter) vehicles involved in those collisions.2

 As a result,

declines in the weight of light trucks tend to decrease fatalities overall.

Sorting out the impact of CAFE standards on vehicle

safety is complicated by the fact that many other factors

also affect safety. Death rates from motor vehicle crashes

have fallen steadily over the past half century, including

during the period when CAFE standards went into effect

and vehicle weights declined (see Figure 4). That trend is

thought to have resulted from better vehicle designs, less

drunk driving, greater use of safety belts, and improved

road design. 

Although vehicle safety has improved, the relevant question with regard to CAFE standards is whether travel in 1. See National Research Council, Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards (Washington,

D.C.: National Academy of Sciences, 2002). 2. Ibid., p. 27.
22 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

1975 1980 1985 1990 1995 2000

0.75

1.00

1.25

1.50

1.75

2.00

2.25

2.50

2.75

Cars

Light Trucks

0

)LJXUH 

Fatality Rates for Cars and

Light Trucks, 1975-2000

(Fatality rate per 100 million vehicle miles traveled)

Source: Congressional Budget Office based on National Highway Traffic Safety

Administration, Traffic Safety Facts 2000 (December 2001), Tables 7

and 8 (available at www-nrd.nhtsa.dot.gov/pdf/nrd-30/NCSA/TSFAnn/

TSF2000.pdf).

today’s lighter cars is less safe than it would have been in

the absence of those standards. Even more relevant is

whether future increases in CAFE standards would lead

to declines in safety.

Using research by the National Highway Traffic Safety

Administration,3

 the majority of committee members concluded that the weight and size reduction of passenger

vehicles that occurred during the late 1970s and early

1980s led to significant increases in crash fatalities. According to the committee’s work, there would have been

1,790 fewer fatalities in 1999 if vehicle weights had been

the same then as they were in 1976.4

 That number would

have been larger in years when cars were even lighter. For

example, the committee estimated that 2,000 lives would

have been saved if vehicle weights in 1993 had been the

same as they were in 1976.5

The committee did not draw any conclusions about what

share of vehicle downsizing and weight reduction since

1975 resulted from the CAFE standards. But it did

conclude that similar decreases in the size and weight of

future vehicles would be likely to produce similar fatality

results. An important—and unanswered—question is how

raising CAFE standards would affect the size and weight

of vehicles in the future. The committee proposed a modification to the current CAFE design that could help prevent weight reductions (see Box 4). 

Not all committee members agreed that CAFE standards

have led to a decrease in vehicle safety. Two of the 13

members stated that the conclusions drawn by the majority

were “overly simplistic and at least partially incorrect.”6

Although the minority agreed that reducing the weight

of relatively light cars (holding the weight of other cars

constant) would cause fatalities to rise, they argued that,

given existing data, it is not possible to understand the

implications of all of the changes in vehicle weight that

have occurred over the past few decades. Specifically, the

minority argued that the “relationships between vehicle

weight and safety are complex and not measurable with

any degree of certainty at present.”7

 Those members maintained that data limitations and uncertainties inherent in

the National Highway Traffic Safety Administration’s research invalidate any of its quantitative results. 

Although the committee focused on how CAFE standards

would affect the severity of accidents, it did not discuss

the impact that CAFE-induced increases in driving might

3. See C.J. Kahane, Effect of Car Size on Frequency and Severity of

Rollover Crashes (National Highway Traffic Safety Administration, 1990).

4. The National Research Council committee estimated the fatality reductions associated with having 1993 cars weigh the same

as 1976 cars and the reductions associated with the increase in

vehicle weights between 1993 and 1999. The Congressional

Budget Office combined those two figures to estimate the fatality implications of having 1999 cars weigh the same as 1976

cars. The 95 percent confidence range for that estimate is between 1,290 and 2,200. 

5. The 95 percent confidence range is between 1,300 and 2,600.

6. National Research Council, Effectiveness and Impact of Corporate

Average Fuel Economy (CAFE) Standards, p. 117.

7. Ibid., p. 123.
CHAPTER FOUR EFFECTS ON SAFETY 23

%R[ 

Changing the Design of CAFE Standards to Improve Auto Safety

Since corporate average fuel economy (CAFE) standards

were introduced, the average difference in weight between

cars and light trucks has widened greatly.1

 At the same

time, the ratio of new cars to new trucks sold has shifted

from about 4 to 1 to near parity.2

 According to many

experts, that combination of trends has significant implications for vehicle safety.3

A recent study of CAFE standards by the National Research Council (NRC) proposes altering the standards’

current design—which focuses on fuel economy for entire

classes of vehicles—so that further regulation of fuel efficiency would not affect safety. Fuel economy is strongly

related to weight; all other things being equal, heavier

vehicles are less fuel efficient than lighter ones. Thus, the

NRC study proposes setting fuel economy targets specific

to vehicle weight: the lighter the vehicle, the more stringent the target it would have to meet.4

 Vehicles above a

certain weight would all have to meet the same target,

reducing automakers’ incentive to build very heavy gasguzzlers.

That system of standards could be designed to yield the

same total fuel efficiency as the current system. As now,

1. National Highway Traffic Safety Administration, “Overview of

Vehicle Compatibility/LTV Issues,” (February 1998), available

at www.nhtsa.dot.gov/cars/problems/studies/LTV/.

2. Light trucks now make up about 47 percent of passenger vehicles

sold; see Environmental Protection Agency, Light-Duty Automotive

Technology and Fuel Economy Trends: 1975 Through 2001, EPA

420-R-008 (September 2001).

3. See, in particular, National Research Council, Effectiveness and

Impact of Corporate Average Fuel Economy (CAFE) Standards

(Washington, D.C.: National Academy of Sciences, 2002).

4. Under current CAFE regulations and in the proposed system,

standards are averages for a manufacturer’s entire fleet of a given

class of vehicles; individual vehicles do not have to meet any

particular standard. The NRC study distinguishes between standards

for a fleet and targets for individual vehicles. In either system,

compliance would be determined at the fleet level; thus, it is

appropriate to refer to individual targets based on weight and an

overall standard for fleet miles per gallon.

each vehicle’s contribution to its manufacturer’s overall

compliance would depend on the gap between its fuel

economy and the relevant target. With weight-based targets, however, the mileage of a lightweight gas-sipper

would no longer tend to exceed the applicable fuel economy target, meaning that lightweight cars would no longer

be especially effective at helping an automaker comply

with the CAFE standards. At the same time, manufacturers

would have an incentive to lighten heavier vehicles that

were subject to a single (non-weight-based) target, because

that would help them comply with the fuel economy

standards.

The expected result of instituting a weight-based CAFE

system would be to discourage the production of very

small and very large vehicles while encouraging a more

uniform and narrower distribution of vehicle weights.

That change would help reverse the growing disparity in

vehicle weights that many experts feel has been a primary

contributor to the apparent safety cost of CAFE regulation. A weight-based system can also be seen as a way to

regulate firms that specialize in fuel-efficient vehicles on

a more equal footing with firms that sell heavier vehicles

(and thus are more constrained by the standards).

Improvements to vehicle safety could come with several

costs, however. The NRC study cites three. First, weightbased targets could lessen regulators’ ability to induce

automakers to improve the overall fuel economy of their

fleets. (Weight reduction is a reliable method for improving fuel efficiency. No matter how stringent weight-based

targets were, they would reduce the cost-effectiveness of

that method.) Second, those targets would diminish companies’ incentives to develop new, stronger lightweight

materials. And third, the average weight of vehicles could

increase, resulting in greater fuel consumption (although

that effect would depend on the specific weight targets

chosen).5

5. National Research Council, Effectiveness and Impact of Corporate

Average Fuel Economy (CAFE) Standards, p. 107.
24 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

have on the total number of accidents. If improvements

in fuel economy led to a greater number of vehicle miles

traveled, the number of accidents—and thus the number

of fatalities—would tend to increase. 

A Gasoline Tax and a

Cap-and-Trade Program

There has been little discussion or study of how a gasolinetax increase or a cap-and-trade program would affect the

safety of driving. Research would be necessary to determine how new vehicles might change as a result of the

higher gasoline prices that those policies would bring

about and how those changes might affect the severity of

accidents. To the extent that higher gasoline prices would

reduce vehicle miles traveled, a policy that raised prices

would tend to lower the number of accidents.
CHAPTER



Effects on Other External Costs

Related to Driving

7he primary motivation for current proposals to reduce gasoline consumption is to lower two external costs

related to that consumption: the United States’ dependence on oil and its carbon emissions. (External costs are

ones whose full weight is borne by society at large rather

than by an individual. Thus, individuals have less incentive

to take those costs into account when making decisions.)

At the same time, tightening corporate average fuel economy standards, raising the federal gasoline tax, or creating

a cap-and-trade program would have implications for

other external costs that result from driving—such as

emissions of air pollutants besides carbon dioxide, traffic

congestion, and the need for highway construction and

maintenance. The three policy options examined in this

study would have indirect effects on those factors, which

would result mainly from changes in the number of vehicle

miles traveled (VMTs).

Emissions of Regulated

Air Pollutants

The Environmental Protection Agency (EPA) regulates

three air pollutants emitted by passenger vehicles: carbon

monoxide, nitrogen oxides, and hydrocarbons (also known

as volatile organic compounds). Carbon monoxide can

irritate people’s respiratory tracts and contribute to coronary damage. Nitrogen oxides and hydrocarbons are precursors to ground-level ozone (smog), which is also a respiratory irritant. EPA sets maximum emission rates (in

grams per mile) for those three pollutants that vehicles

are required to meet. Pollution-control equipment installed on vehicles is intended to prevent emissions from

exceeding those rates.1

 As a result, improving the fuel

economy of vehicles does not imply lower emission rates

of those pollutants.2

 (However, those emissions will decline starting in a few years when stricter EPA standards

go into effect.)3

Although not altering emission rates, higher CAFE standards could indirectly affect the total amount of those

1. In addition, the federal government requires vehicle emission

inspections in certain areas that exceed standards for atmospheric ozone.

2. One study found that for model years 1979 through 1990, cars

that got fewer miles per gallon had significantly greater carbon

monoxide and hydrocarbon emissions than higher-MPG cars

did. The author attributes that result to the degradation of

pollution-control equipment over time. He cautions, however,

that improvements in the reliability of that equipment since the

1979-1990 period could help keep emission rates from rising

with fuel consumption as vehicles age in the future. Thus, he

concludes, further tightening of CAFE standards would not

necessarily reduce emissions. See Winston Harrington, “Fuel

Economy and Motor Vehicles,” Journal of Environmental Economics and Management, vol. 33, no. 3 (July 1997), pp. 240-

252.

3. EPA will implement its stricter Tier 2 emissions standards beginning in 2004. Although standards for light trucks are currently less stringent than those for cars, by 2009 all passenger

vehicles will be subject to the same emissions standards for the

three pollutants.
26 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

vehicle emissions.4 By lowering the cost of operating a

vehicle, higher CAFE standards would increase vehicle

miles traveled—by roughly 2 percent for each 10 percent

increase in CAFE stringency.5

 More driving would mean

more tailpipe emissions. 

Gauging the total effect on emissions of those three

pollutants, however, also requires accounting for changes

in emissions that occur during the production and delivery

of gasoline. Since an increase in CAFE standards would

decrease gasoline consumption, it would reduce production- and delivery-related emissions. A life-cycle analysis

of automobile-related air pollutants indicates that those

fuel-production stages (from extraction of raw materials

to delivery of the fuel to the final user) generate emissions

of nitrogen oxides and volatile organic compounds

“roughly equal to the emissions resulting from the lifetime

of the vehicle.”6

 On net, therefore, higher CAFE standards

would reduce total emissions of nitrogen oxides and volatile organic compounds, because decreases in productionand delivery-related emissions are estimated to outweigh

the increase in tailpipe emissions from greater VMTs. For

carbon monoxide, by contrast, fuel production and delivery generate comparatively small amounts of emissions.7

Thus, an increase in CAFE standards would be expected

to lead to a small rise in carbon monoxide emissions because of the rise in VMTs. 

As with tighter CAFE standards, a higher gasoline tax or

a cap-and-trade program would induce long-term increases

in vehicles’ fuel economy. Although that would not

necessarily lower tailpipe emission rates of the three

regulated pollutants, it would lower the total amount of

those pollutants emitted, both by reducing productionand delivery-related emissions and by discouraging VMTs.

Congestion

A recent comparison of the external costs of driving found

that costs associated with traffic congestion (such as lost

time and productivity and delays in deliveries) exceed

other external costs, including those from emissions of

regulated pollutants and carbon dioxide and from motor

vehicle accidents. That study used a cost estimate for congestion of 5 cents per mile, or $1 per gallon of gasoline.8

Researchers have estimated congestion costs at between

1.2 cents and 14.8 cents per mile, or between $0.24 and

$2.96 per gallon.9

All three policies discussed in this study would affect

congestion indirectly by altering vehicle miles traveled:

a higher gasoline tax or a cap-and-trade program would

tend to lower VMTs (by raising gasoline prices), whereas

tighter CAFE standards would tend to increase them (by

lowering the operating costs of vehicles). None of those

policies would be expected to have a big impact on the

level of congestion. But given the large potential costs

associated with congestion, even small policy-induced

changes in the amount of driving could have significant

economic costs.

None of those policies is well suited to discourage traffic

congestion, which is primarily a problem of peak-period

demand. The decline in VMTs from a gasoline-tax

increase or a cap-and-trade program would not necessarily

occur mainly during peak periods. Moreover, using CAFE

4. One study addresses that issue directly, estimating the change in

pollutants that would result from a three-mile-per-gallon increase in fuel economy requirements for all passenger vehicles.

The study finds that emissions of the three regulated pollutants

would rise by 1.6 percent to 1.9 percent, primarily because of

the expected increase in VMTs. See Andrew N. Kleit, Shortand Long-Range Impacts of Increases in the Corporate Average Fuel

Economy (CAFE) Standard (Washington, D.C.: Competitive

Enterprise Institute, February 7, 2002), available at www.cei.

org/pdf/2398.pdf.

5. See note 11 in Chapter 2.

6. Lester Lave and others, “Life-Cycle Analysis of Alternative Automobile Fuel/Propulsion Technologies,” Environmental Science

and Technology, vol. 34, no. 17 (August 2000), p. 3601. 

7. Fuel production generates only about 2 percent of the carbon

monoxide emissions that would come from the tailpipe of a car

that complied with existing emission requirements; ibid., p.

3601.

8. See Ian W.H. Parry, “Does Tightening CAFE Do More Harm

Than Good?” (working paper, Resources for the Future, September 2002).

9. See Ian W.H. Parry and Kenneth A. Small, Does Britain or the

United States Have the Right Gasoline Tax? Discussion Paper 02-

12 (Washington, D.C.: Resources for the Future, March 2002),

p. 16.
CHAPTER FIVE EFFECTS ON OTHER EXTERNAL COSTS RELATED TO DRIVING 27

standards to reduce congestion would entail lowering those

standards. Policies that target the cost of peak-period driving directly, such as tolls levied during those periods, are

better suited for addressing congestion problems.

Highway Construction and

Maintenance

By altering VMTs, an increase in CAFE standards or the

federal gasoline tax or enactment of a cap-and-trade program would also indirectly affect requirements for highway construction and maintenance. Unless the scale of

those policy changes was very large, however, the effects

on miles traveled would be small. The resulting change

in spending needed to continue current levels of highway

construction and maintenance would most likely be

smaller still.

Raising CAFE standards is the only one of the three

policies that would be expected to stimulate demand for

highway travel, and that increase in demand would occur

gradually over a decade or so. Meanwhile, peak-period

demand for highway travel will probably continue to grow

independent of any change in the stringency of CAFE

standards. That growth is likely to outweigh the effects

of all but very large changes in CAFE standards and to

be a much more important determinant of highway construction requirements.

The need for highway maintenance is largely determined

by road degradation from vehicle travel. Damage to roads

is primarily caused by freight and other heavy-duty

trucks.10 A higher gasoline tax would discourage some

travel by light-duty vehicles but would not affect heavier,

diesel-powered vehicles (unless the tax on diesel fuel was

also raised). The same would be true of a cap-and-trade

program geared toward gasoline combustion. Similarly,

the increased travel caused by higher CAFE standards

would be limited to vehicles that weigh less than 8,500

pounds. Thus, the effect of any of those policy changes

on highway maintenance needs is likely to be very small.

10. A moderately loaded tractor trailer can weigh more than 60,000

pounds, whereas the heaviest sport utility vehicles weigh little

more than 8,500 pounds. The difference in road damage associated with those vehicles is only partly reflected in differences in

taxes on fuel and other taxes and fees.

CHAPTER



Other Policy Implications:

Distributional and Revenue Effects

7he policies to reduce gasoline consumption described

in this study are not aimed at altering the income distribution in the United States or raising federal revenue. Nonetheless, increasing the federal gasoline tax, tightening corporate average fuel economy standards, or enacting a capand-trade program would have distributional and revenue

effects, which policymakers might want to take into consideration. 

Studies suggest that a gasoline-tax increase would impose

higher costs on rural households than on urban households, but they disagree about how those costs would be

distributed among households at different income levels.

Depending on how it was designed, a cap-and-trade program could have similar distributional effects to those of

a gasoline tax. Little research is available about the distributional effects of raising CAFE standards.

Increasing the gasoline tax would boost federal revenues

(despite the decline in gasoline use that would result),

whereas increasing CAFE standards would lower revenues.

Under current law, additional receipts from a rise in the

federal gasoline tax would be dedicated to the Highway

Trust Fund, which pays for highways and mass transit.

With changes to current law, those receipts could be used

in myriad ways, which could have widely varying implications for the economy. The revenue effects of a cap-andtrade program would depend on whether the government

chose to sell emission allowances or to give them away.

Distributional Effects

A policy change to decrease gasoline consumption will

impose different burdens on households depending on

their income level and where they live. Several researchers

have examined how the effects of a higher gasoline tax

would differ among U.S. households on the basis of those

two factors, but few have examined the distributional effects of higher CAFE standards. Some studies have looked

at the distributional effects of an economywide cap-andtrade program for carbon emissions,1

 but no research has

been done on the effects of a cap-and-trade program that

applies only to carbon emissions from gasoline use. 

Effects on Households at Different Income Levels 

Some advocates of raising CAFE standards argue that

doing so would be more equitable than increasing the

gasoline tax because gasoline taxes are regressive—in other

words, they disproportionately burden people with lower

income. That assertion is based on surveys of household

consumption that find that gasoline purchases take up a

much larger fraction of measured annual income for lowerincome households than for higher-income households.

However, spending on gasoline as a share of annual

income may not be a good measure of the regressivity of

1. See Congressional Budget Office, Who Gains and Who Pays

Under Carbon-Allowance Trading? The Distributional Effects of

Alternative Policy Designs (June 2000).
30 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

7DEOH 

Estimated Burden of Gasoline Spending on Households

(In percent)

Income or

Spending Decilea

(Lowest to highest)

Gasoline Spending

as a Share of

Income, 1986b

Average Family Gasoline

Spending as a Share of

Average Family Income,

1976-1986c

Gasoline and Motor Oil

Spending as a Share of

Total Spending, 1986b 

1 11.44 3.9 3.70

2 6.54 5.3 5.34

3 6.36 5.1 5.53

4 6.08 5.0 5.67

5 4.97 4.6 5.17

6 4.69 4.3 5.20

7 4.38 4.0 4.94

8 3.75 3.8 4.43

9 3.56 3.4 4.47

10 2.40 2.5 3.20

Source: Congressional Budget Office based on the sources cited below.

Note: Total spending includes the imputed value of rents and automobiles.

a. Each decile contains 10 percent of U.S. households, ranked on the basis of their income or their total annual spending.

b. From James M. Poterba, Is the Gasoline Tax Regressive? Working Paper No. 3578 (Cambridge, Mass.: National Bureau of Economic Research, January 1990).

c. From Howard Chernick and Andrew Reschovsky, “Who Pays the Gasoline Tax?” National Tax Journal, vol. 50, no. 2 (June 1997), pp. 233-259.

a gasoline tax. Using other measures, evidence about

whether a gasoline-tax increase would be regressive is

mixed. 

The Burden of Gasoline Taxes. Many researchers believe

that taxes should be compared with a household’s longterm, or permanent, income rather than its annual income.2

 Measuring the tax burden relative to permanent

income provides an estimate of a household’s ability to

bear a tax over a lifetime. Annual income, by contrast,

could substantially underestimate the long-term ability

of some households to pay a tax. For example, households

with retired workers may have small annual incomes but

large savings. In addition, households with people who

are early in their careers may have low current incomes

but expect substantially higher incomes in the future. 

Howard Chernick and Andrew Reschovsky estimated an

“intermediate-run” gasoline-tax burden.3

 They looked at

average gasoline spending by families during the 1976-

1986 period as a percentage of average family income in

that period. Their results show that gasoline expenditures

generally accounted for a larger share of average income

for lower-income households than for higher-income

households (see Table 2), which suggests that a rise in the

gasoline tax would tend to be regressive. However, a

drawback of their analysis is that it does not account for

shortcomings in the available data on household income.

Evidence suggests that those data may understate the

resources available to some households—particularly at

the bottom end of the income scale, where unreported

income and private transfers (such as gifts from family

2. For a discussion of annual versus permanent measures of income, see Congressional Budget Office, Federal Taxation of

Tobacco, Alcoholic Beverages, and Motor Fuels (August 1990);

Gilbert Metcalf, “A Distributional Analysis of Green Tax Reforms,” National Tax Journal, vol. 52, no. 4 (December 1999),

pp. 655-681; and Diane Lim Rogers and Don Fullerton, Who

Bears the Lifetime Tax Burden? (Washington, D.C.: Brookings

Institution, 1993).

3. See Howard Chernick and Andrew Reschovsky, “Who Pays the

Gasoline Tax?” National Tax Journal, vol. 50, no. 2 (June

1997), pp. 233-259.
CHAPTER SIX OTHER POLICY IMPLICATIONS: DISTRIBUTIONAL AND REVENUE EFFECTS 31

members) may constitute a larger share of household

resources.4

 

Some researchers believe that a household’s spending

provides a better measure of its long-term ability to pay

a tax than its income does. Spending reflects both expectations of higher future income (to the extent that people

can borrow money) and household saving (as people draw

on accumulated resources). Thus, expenditures reflect

households’ permanent income better than annual income

does. In addition, using expenditure data avoids the

problem of understated household resources. 

When gasoline spending is measured as a share of total

expenditures, evidence on the distributional effects of a

gasoline-tax increase is mixed. For example, the Congressional Budget Office found that spending on all motor

fuels made up about 3 percent of total expenditures for

the bottom four-fifths of the income distribution and 2.3

percent of total expenditures for the highest one-fifth.5

A study by James Poterba ranked households in tenths

(or deciles) on the basis of their total spending and found

that gasoline and motor oil accounted for a smaller share

of total expenditures for households in the lowest-spending

decile than for households in all but the top-spending

decile (see Table 2).6

 However, that study also found that

the second, third, and fourth deciles had higher expenditure shares than any of the other deciles. 

Data that are viewed at the decile level may hide considerable variation in households’ burdens within deciles. For

example, the Poterba study found that among households

in the lowest decile, one-third reported no direct spending

on gasoline, whereas 14 percent reported that gasoline

accounted for more than one-tenth of their total spending.

An increase in the gasoline tax, therefore, would impose

a relatively large burden on those 14 percent of lowincome households unless they received some compensation.

One way to at least partly offset higher gasoline-tax payments would be to increase government payments for

some low-income households. Government payments that

rise each year with changes in the consumer price index

(such as Social Security benefits and Supplemental Security

Income payments) would automatically increase as a result

of a higher gasoline tax—provided that the tax caused the

consumer price index to rise. 

Indexed government payments generally make up a much

larger share of income for lower-income households than

for higher-income households. For example, Poterba

found that indexed transfer payments constituted twothirds of income for households in the lowest-spending

decile. He estimated households’ “unindexed exposure”

to changes in gasoline taxes—that is, the share of higher

gasoline spending that would not be offset by higher

transfer payments. Poterba found that unindexed gasoline

spending accounted for only 0.7 percent of total income

for households in the lowest-spending decile and 2.8 percent for the second decile. Unindexed gasoline spending

accounted for between 4.5 percent and 5.7 percent of total

income for households in the remaining deciles.7

The rise in indexed transfer payments would depend on

average gasoline consumption. Lower-income households

that received transfer payments but consumed more than

the average amount of gasoline would bear larger tax burdens than Poterba estimated.

The Burden of a Cap-and-Trade Program. The distributional effects of a cap-and-trade program would have two

components: the effects of the increase in the price of

gasoline and the effects of the decision about how to allocate emission allowances.

4. Studies that compare consumption with income find that consumption can look too large relative to income for poorer households. For example, according to reported data, households in

the lowest fifth of the income distribution consume more than

twice their annual income. See Congressional Budget Office,

Who Gains and Who Pays Under Carbon-Allowance Trading?

p. 18.

5. See Congressional Budget Office, Federal Taxation of Tobacco,

Alcoholic Beverages, and Motor Fuels.

6. See James M. Poterba, Is the Gasoline Tax Regressive? Working

Paper No. 3578 (Cambridge, Mass.: National Bureau of Economic Research, January 1990). 7. Ibid., pp. 19-20.
32 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

Like a gasoline tax, a cap-and-trade program would raise

the price of gasoline.8

 That price rise would have the same

distributional effects as one resulting from a tax increase.

The second component would depend on policymakers’

decision about how to allocate the allowances, which could

have considerable value.9

 If policymakers chose to distribute them for free (for example, to producers and importers

of gasoline), then the policy would create windfall profits

for the recipient firms, and their shareholders would benefit. Stocks contribute a larger share of income for higherincome households than for lower-income ones, so giving

the allowances away would tend to benefit higher-income

households. (It would be analogous to taxing gasoline

consumption and distributing the revenue to gasoline

producers and importers.)

If, by contrast, policymakers chose to sell emission allowances through an auction, the government would capture

the value of the allowances. In that case, the distributional

effects of the cap-and-trade program would be equivalent

to those of a rise in the gasoline tax. The ultimate distributional impact would depend on what the government

chose to do with the auction revenue. 

The Burden of CAFE Standards. None of the ways of

measuring the incidence of a gasoline tax that were discussed above shed light on how its distributional effects

would compare with those of higher CAFE standards.

Moreover, no research on the distributional effects of an

increase in CAFE standards is currently available. 

Raising CAFE standards would directly affect the prices

of new vehicles. That effect would tend to be progressive,

assuming that new-car purchases make up a larger share

of spending for higher-income households than for lowerincome households. However, a complete picture of the

distributional effects of higher CAFE standards would

require understanding their indirect effects. For example,

raising CAFE standards would be likely to increase the

demand for used cars, leading to higher used-car prices

as well. 

Distributional Effects Among Regions 

The effects of a gasoline-tax increase would vary among

households in different parts of the country. In general,

costs per household would be greater in rural areas than

in urban areas. 

Researchers at Resources for the Future (RFF) examined

the regional impact of a 4.3-cent-per-gallon increase in

the federal gasoline tax that took effect in 1993.10 Although the magnitude of RFF’s results was specific to that

tax increase, the pattern of the results suggests how the

effects of any rise in the federal gasoline tax would vary

among parts of the country. Rural households would tend

to see a greater increase in their tax payments than urban

households would because they tend to drive more miles.

RFF concluded that, on average, urban households would

pay $32 more (in 1990 dollars) in taxes each year because

of the 4.3-cent tax increase. Suburban households would

pay an average of $39 more, and rural households would

pay $45 more. On average, people in western and midwestern states would tend to see greater increases in their

gasoline-tax payments than people in eastern states would

(see Figure 5). 

The variation in tax burdens among regions was greater

when measured as a share of household income than when

measured in dollars (see Figure 6). The region that paid

the most in percentage terms (the west south central states)

had a tax burden that was 82 percent higher than the

region with the smallest tax burden (the mid-Atlantic

states). Measured in dollar terms, by contrast, the highestpaying region (the mountain states) paid 64 percent more

than the lowest-paying region (the mid-Atlantic states).

That difference indicates that regions that would tend to 8. The price increase would be the same regardless of whether the

government distributed carbon allowances for free or sold them

in an auction.

9. For a more detailed discussion about the distributional effects of

allocation decisions, see Congressional Budget Office, Who

Gains and Who Pays Under Carbon-Allowance Trading? and An

Evaluation of Cap-and-Trade Programs for Reducing U.S. Carbon

Emissions (June 2001).

10. See Alan J. Krupnick, Margaret A. Walls, and H. Carter Hood,

The Distributional and Environmental Implications of an Increase

in the Federal Gasoline Tax, Discussion Paper ENR 93-24

(Washington, D.C.: Resources for the Future, September

1993).
CHAPTER SIX OTHER POLICY IMPLICATIONS: DISTRIBUTIONAL AND REVENUE EFFECTS 33

$46

$42 $43

$44

$40

$41

$36

$28

$36

U.S. Average = $39

)LJXUH 

Annual Cost to Households in Different Regions from a 4.3-Cent Rise in

the Federal Gasoline Tax

(In 1990 dollars)

Source: Congressional Budget Office based on Alan J. Krupnick, Margaret A. Walls, and H. Carter Hood, The Distributional and Environmental Implications of

an Increase in the Federal Gasoline Tax, Discussion Paper ENR 93-24 (Washington, D.C.: Resources for the Future, September 1993).

Note: Numbers represent the net effect of higher federal gasoline-tax payments and of lower state gasoline-tax payments from reduced gasoline consumption.

experience higher tax payments also tend to have lower

average income. 

In February 1993, the Congressional Budget Office

(CBO) testified about the possible effects of a 24-centper-gallon increase in the tax on motor fuels.11 Like the

RFF researchers, CBO concluded that the tax would impose a higher average cost on rural households than on

urban ones. The average cost for all households was estimated at $179 per year (in 1994 dollars), compared with

an average cost for rural households of $219 per year.

Among urban households, the average annual cost was

lowest in the Northeast ($157) and highest in the South

($181).12 Of course, the ultimate distributional effects

would depend on what the government did with the

additional gasoline-tax revenue. That revenue could be

used to offset disparities in regional effects.

11. See the statement of Robert D. Reischauer, Director, Congressional Budget Office, before the Senate Committee on Energy

and Natural Resources, February 24, 1993.

12. The average annual costs for urban households in the Midwest

and West were $170 and $179, respectively.
34 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

0.127

0.109 0.134

0.144

0.120

0.136

0.094

0.079

0.107

U.S. Average = 0.112%

)LJXUH 

Annual Cost to Households in Different Regions from a 4.3-Cent Rise in

the Federal Gasoline Tax, as a Share of Household Income

(Percent)

Source: Congressional Budget Office based on Alan J. Krupnick, Margaret A. Walls, and H. Carter Hood, The Distributional and Environmental Implications of

an Increase in the Federal Gasoline Tax, Discussion Paper ENR 93-24 (Washington, D.C.: Resources for the Future, September 1993).

Note: Numbers represent the net effect of higher federal gasoline-tax payments and of lower state gasoline-tax payments from reduced gasoline consumption.

A cap-and-trade program that caused equivalent price

increases to those described above would be expected to

have similar regional effects. (Although the government

could use the revenue from auctioning allowances in a way

that would offset those effects.) CBO could not find any

evidence on the regional impact of CAFE standards. 

Effects on Federal Revenue

An increase in the federal gasoline tax (which is currently

18.4 cents per gallon) would bring in additional federal

revenue because a higher tax rate would be charged on

each gallon of gasoline consumed. At the same time, the

higher rate would discourage gasoline consumption. The

less elastic that gasoline purchases are—in other words,

the less that people reduce their consumption when the

price rises—the more that revenue would increase as the

tax rate rose (and vice versa). 

CBO estimated the additional revenue that would result

from raising the federal gasoline tax by 15 cents per gallon

—which would represent about a 10 percent price increase, at current prices. (That tax increase is not suggested

as optimal but was chosen for illustrative purposes.)

Accounting for both the expected growth in gasoline

consumption (in the absence of the tax increase) and the
CHAPTER SIX OTHER POLICY IMPLICATIONS: DISTRIBUTIONAL AND REVENUE EFFECTS 35

7DEOH 

Revenue Effects of a 15-Cent Increase in the Federal Gasoline Tax

Gasoline Consumption

(Millions of gallons)

Total Federal

Revenue Collected 

(Billions of dollars)

 Increase in Federal

Revenue Because

of the Tax Increase

(Billions of dollars)

Without

Tax Increase

With

Tax Increase

Without

Tax Increase

With

Tax Increase

Short Term (2003) 112,279 109,360 20.7 36.5 15.8

Longer Term (2012)a 143,855 131,483 to 138,388 26.5 43.9 to 46.2 17.4 to 19.7

Source: Congressional Budget Office.

a. The first and second numbers in the ranges are based on long-term price elasticities of -0.86 and -0.38, respectively. For more details, see Box 3 on page 17.

effect of the tax increase on that growth (using the elasticities described in Box 3 on page 17), CBO estimated that

a 15-cent-per-gallon rise in the gasoline tax today would

add nearly $16 billion to federal gasoline-tax revenue in

2003, an amount that would grow to between $17 billion

and $20 billion in 2012 (see Table 3).13 Unless states and

localities also raised their gasoline taxes, their tax receipts

would fall because of the decline in gasoline consumption.

If lawmakers removed the restriction that all gasoline-tax

receipts go to the Highway Trust Fund, the government

could use the additional revenue from a higher gasoline

tax in many ways—such as paying down the national debt,

spending more on federal programs, offsetting the distributional effects associated with a gasoline-tax increase, or

decreasing certain taxes that discourage overall economic

activity. The total cost that the gasoline-tax increase would

impose on the economy would depend, in part, on the

way the government chose to use the revenue. For example, using gasoline-tax receipts to offset existing taxes on

capital and labor—such as payroll taxes and the corporate

income tax—could benefit the economy by reducing those

taxes’ adverse incentives. (Taxes on labor and capital discourage households from working and saving and businesses from hiring additional employees and investing

more.) In contrast, using gasoline-tax receipts to offset

some of the distributional effects of the tax increase would

not benefit the economy, but it might cause the policy

change to be seen as more equitable. 

The effects of a cap-and-trade program on federal revenue

would depend on whether the government sold emission

allowances or distributed them for free. If the government

auctioned off the allowances, the effects would be similar

to those of a gasoline tax, and government revenue (including auction receipts and gasoline-tax receipts) would

rise. If the government gave the allowances away, gasolinetax receipts would fall (because of the decline in gasoline

consumption), and the government would not collect any

money for the allowances. 

An increase in CAFE standards would have an indirect

effect on revenue collected for the Highway Trust Fund.

Improvements in the fuel economy of new vehicles would

reduce their gasoline consumption per mile traveled and

thus bring in fewer gasoline-tax receipts. That decline in

receipts would be partly offset as lower driving costs led

to more vehicle miles traveled. (Research indicates that

increases in VMTs due to lower driving costs could offset

the gasoline savings from CAFE-induced changes in fuel

economy by roughly 20 percent.) The decline in gasolinetax revenue because of higher CAFE standards would

increase over time as older vehicles were replaced by new

vehicles that met the more-stringent standards.

13. Those estimates assume that the full amount of the tax increase

is passed on to consumers in the form of higher gasoline prices.

The discouraging effect on driving would be lessened to the

extent that producers absorbed the tax increase without passing

it on.
36 REDUCING GASOLINE CONSUMPTION: THREE POLICY OPTIONS

Raising the gasoline tax, tightening CAFE standards, or

enacting a cap-and-trade program would also affect federal

revenue in other, less direct ways. By imposing costs on

producers and consumers, all of those policies would tend

to discourage economic activity. That decrease in economic activity would lead to lower tax receipts in multiple

ways—for example, collections of corporate income taxes

would decline if the profits of automakers or gasoline

companies fell.

The size of those indirect effects on tax collections would

vary with the economic cost of the policy adopted. That

cost in turn would depend on the targeted reduction in

gasoline consumption (bigger reductions would be more

costly than smaller ones) and the comprehensiveness of

the policy. As discussed in Chapter 2, policies that encourage all gasoline-saving activities will produce a given

gasoline reduction at a lower cost than policies that focus

on a limited number of activities. 

Further, for a gasoline tax or a cap-and-trade program,

the total cost imposed on the economy would depend on

how lawmakers opted to use the revenue from the gasoline

tax or from an allowance auction. For example, using those

receipts to encourage economic activity (perhaps by reducing taxes on capital or labor) would lead to lower total

costs than using those receipts to offset the distributional

effects of the policy.