EPA Evaluation of Aftermarket
Gas-Saving Products
The U.S. Environmental Protection Agency (EPA) conducts a
program to evaluate aftermarket retrofit devices that are intended
to improve vehicle fuel economy and/or reduce exhaust emissions.
Through engineering, scientific, and statistical analysis of data ob-
tained from independent and EPA laboratory testing, the evaluation
program objectively determines the effects a device may have on fuel
economy and exhaust emissions; when necessary, durability and
drivability testing may be evaluated as well.
Purpose of the Program
The purpose of the program is to generate, analyze and disseminate technical data
in a public document. Participation in the program is voluntary unless ordered by
the EPA Administrator or the Federal Trade Commission. All voluntary testing is
paid for by the applicant. The program is restricted to four-wheeled highway vehicles
weighing 6,000 pounds or less.
Fuel additives are included in this program; however, oil additives and lubricants
are not. A complete report is issued for any product evaluated by EPA. There is no
approval, certification, endorsement, nor registration of any product tested in this
program. Furthermore, EPA does not certify, approve, register, or endorse any inde-
pendent laboratory or the results of any independent laboratory testing. Any claims
of EPA certification in this program are false.
Overview of Testing
The EPA device evaluation program employs the same scientific laboratory test
methods used to certify vehicles in the United States. The specific tests are the
Federal Test Procedure (FTP) and the Highway Fuel Economy Test (HFET). Each of
these involve placing the test vehicle on a dynamometer (a laboratory test apparatus
which simulates road conditions) and driving through a specified trace simulating
Office of Transportation and Air Quality
United States
Environmental Protection EPA420-F-01-035
A9encv September 2001
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city and highway driving in consecutive test sequences. Exhaust gases are captured, analyzed,
and used to determine the rate of each criteria pollutant emission in grams per mile (gms/mi)
and to calculate fuel economy in miles per gallon (mpg).
The controlled laboratory conditions and use of a standard test fuel in this evaluation program
minimizes variables one would have to address when using actual outdoor driving on roadways.
Laboratory testing assures that the test results' comparisons, with and without the device, are
not influenced by outside, uncontrollable factors.
EPA conducts tests on at least two different vehicles which are representative of the fleet. Each
vehicle is thoroughly inspected and maintained as it was originally certified by EPA before
testing. A minimum of three tests using each test vehicle without the device are conducted to
establish a base line. The device is then installed on the vehicle as instructed by the manufac-
turer and the same three test series are conducted once again. When completed, the device is re-
moved and the initial series of tests are conducted once again to determine whether the vehicle
has been affected by using the device.
The data obtained from testing are analyzed for statistically significant differences, either posi-
tive or negative. Emission results for each of the criteria pollutants, carbon monoxide, hydro-
carbons, and nitrogen oxides are compared for these differences. If use of a device results in a
statistically significant increase of any of the criteria pollutants, EPA would consider installa-
tion of the device as tampering with the emission control system even though fuel economy
might be improved.
Applicants for this voluntary program are invited to be present during installation and testing of
the device at EPA's test laboratory located in Ann Arbor, Michigan.
For More Information
For further details on the evaluation program, go to:
www.epa.gov/otaq/consumer/b00003.pdf
Available reports may be viewed from this Web site by selecting the link associated with the
alphabetical listing of evaluated product names.
EPA Evaluation of Aftermarket Gas-saving Products
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