environmental facts
FEDERAL RATINGS OF FUEL ECONOMY FOR 1975 CARS
To meet the requirements of the Clean Air Act, the U.S.
Environmental Protection Agency must test new cars to cer-
tify that they meet air pollution requirements. In mak-
ing these tests, EPA obtains data which can be used to
calculate the fuel economy of cars under representative
driving conditions.
For the 1975 model year, EPA has compiled fuel
economy figures for all automobiles that were certified by
EPA as of September 15, 1974. These figures are being
published jointly by EPA and the Federal Energy Administra-
tion in a booklet, "1975 Gas Mileage Guide for New Car
Buyers," free on request from the General Services Adminis-
tration's Consumer Information Center, Pueblo, Colorado
81009. A second edition early in 1975 will include fuel
economy data on cars and light-duty trucks yet to be cer-
tified.
Moreover, automakers are voluntarily putting EPA-FEA
labels on all their 1975 models to show prospective buyers
the results of the EPA tests.
The fuel economy rating and labeling program of the
two agencies is designed to encourage energy conservation
in the use of automobiles by:
* Helping the public understand what aspects of
car design and equipment tend to reduce fuel
consumption,
* Influencing manufacturers to make vehicles that
have better fuel economy, and
* Influencing the public to buy vehicles that have
better fuel economy.
The Gas Mileage Guide;
The principal mileage guide covers passenger cars
offered for sale in the United States. Cars intended for
sale in California are listed in a separate guide, because
California's exhaust emission standards are different from
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY • WASHINGTON, B.C. 20460
-------
-2-
the Federal standards that apply elsewhere. California
cars are certified separately.
The 1975 guide has several features that are designed
to make the information more useful and meaningful
to the car buyer:
* 1975 models are rated for two types of use: city
driving and highway driving. Cars normally get
more miles per gallon of fuel at steady-speed
highway driving than in slower, stop-and-go city
driving. This distinction can be useful to the
buyer who knows how much of each type of driv-
ing he does.
* Each model is listed only once—miles-per-gallon
data are sales weighted.
* The ratings are arranged alphabetically by manu-
facturer, and by "car line"—the maker's name
for cars with common characteristics of chassis
and body construction. (For example, Nova, Torino,
and Gremlin are car lines for Chevrolet, Ford, and
American Motors cars.)
When more than one engine size and fuel system are
available in a car line, separate fuel economy figures are
given for each. If the car is equipped with a catalytic
converter, that fact is noted. Station wagons are listed
separately, but no distinctions are made for other body
styles, number of doors, trim options, etc.
The Labeling Program
Most automakers have agreed to label each new car
with the miles-per-gallon information supplied by EPA for
that model. The label will be attached to a rear window,
like the price sticker. The maker has a choice of label
types: one giving an average rating for that car line and
engine; one giving a range as well as the estimated average;
one listing all figures for a car line, with that model under-
lined or circled; and one specifying the fuel economy results
of the cars tested with the same transmission, axle ratio,
and weight, as well as the same engine and fuel system.
Because of these options the data presented on the label
will not always be identical with the data in the mileage
guide which gives only an average rating for each car line
and engine series.
How the Tests are Conducted
EPA tests cars for exhaust emissions and fuel economy
at its laboratory in Ann Arbor, Michigan. Each car is driven
on a dynamometer, a machine that permits a typical driving
cycle in the laboratory. Vehicle loads, starts and stops,
speeds and distances can be simulated accurately, while
data on fuel burned and emissions produced are recorded.
-------
-3-
Each vehicle is tested under exactly the same conditions, some-
thing impossible to achieve with road testing.
The city-driving test cycle simulates the conditions
encountered when a typical driver commutes from home to work
and back. Average speed is 20 miles per hour, with many starts
and stops. The test takes 28 minutes.
The highway driving test, performed only for fuel economy
measurement, simulates driving on interstate highways and rural
roads. Average speed is 49 miles per hour. The test takes 12
minutes.
Fuel economy figures for city and highway driving are
computed from the dynamometer tests. To determine compliance
with anti-pollution requirements, it is not necessary to test
every possible engine-fuel system-weight combination. Therefore,
to calculate the sales weighted fuel economy, by weight, of
each engine-fuel system combination in each car line, EPA
has used some additional data supplied by the automakers on
different weight vehicles in some engine-fuel system combi-
nations that were missing from its own measurements of emission-
test vehicles. In addition, manufacturers have supplied
fuel economy data applicable to vehicles of a certain engine,
fuel system, catalyst, axle ratio, and transmission.
When such maker-supplied data have been used, the Agency
requires that Federal testing procedures be followed and
detailed engineering reports made. Some have been accepted
and used to expand the fuel economy information to more
varieties of car lines, engines, and equipment. Some have
been rejected. And in some cases EPA has performed its own
tests to confirm the manufacturers' results.
What the Tests Mean to_the New Car Buyer
An EPA fuel economy figure is not a guarantee of fuel
economy on a given car. They are estimates, the best estimates
that can be made from careful laboratory testing and stat-
istical analysis.
The mileage guide figures tell the new car buyer the
relative fuel economy for most of the choices available to
him as the make, model, engine, and fuel system.
But the actual fuel economy an individual car owner
will experience will depend on the type of driving he does,
and, of course, the mileage guide figures cannot indicate the
fuel-economy costs of bad driving habits and lax maintenance.
A heavy foot on the gas and the brake, frequent starts and
stops, long periods of idling, and driving at uneven speeds
all mean fewer miles to the gallon. And no car will achieve
its best gas mileage unless it is well maintained and kept
in good condition.
September 1974
-------
OFFICE OF PUBLIC AFFAIRS (A-107)
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
POSTAGE AND FEES PAID
ENVIRONMENTAL PROTECTION AGENCY
EPA-335
THIRD CLASS BULK RATE
------- |