EPA to go public with results of vehicle mpg audits

WASHINGTON -- After cracking down on Hyundai, Kia and Ford, the EPA is preparing to shine a more public spotlight on automakers' fuel economy claims.

This fall, the agency plans to release the results of industrywide audits that included tests on more than 20 car and light-truck models this year, said Christopher Grundler, head of the EPA's Office of Transportation and Air Quality, in an interview last week.

The audits, done at tracks in Arizona and Michigan, were meant to double-check automakers' readings on the "coast-down" test -- the test that turned up problems with the mpg numbers on many of Hyundai's and Kia's window stickers last year, and has led the companies to spend millions of dollars compensating vehicle owners.

Grundler, who was recently briefed on the results, said he can't comment on what the EPA found until he talks to his bosses and briefs executives from the car companies. But he said the upcoming report "will be very interesting to some people."

The coast-down test, in which a vehicle is sped up to about 80 mph and then allowed to glide to a stop, measures the aerodynamics of a vehicle, the rolling resistance of its tires and the amount of friction in its drivetrain. The readings are used to program a dynamometer, like a treadmill for vehicles, which is used to run the vehicle through the EPA's test cycles and come up with mpg estimates.

Initial audits

Until about three years ago, the EPA didn't regularly audit the coast-down numbers that car companies submitted. Grundler's predecessor, Margo Oge, ordered an initial round of audits in 2010, hoping to deter cheating as fuel economy started to become a bigger factor in customers' buying decisions.

Last summer, the EPA briefed automakers on audits of their own cars. But this fall's report would be the first time the agency's audit results would be made public. And it would put the numbers in the hands of rival automakers, many of which are running coast-down tests on one another's cars to verify the results.

American Honda -- which had been unseated by Hyundai as the most fuel-efficient automaker in the eyes of the EPA, but regained its title last year after the agency launched its investigation into the Korean brand -- said it will welcome the EPA's report as a step toward more consistent fuel economy testing across makes and models.

The report "should help ensure the integrity of EPA fuel economy ratings that are a valuable resource to consumers," a Honda spokesman wrote in an e-mail. "We are confident that our application of the EPA's fuel economy rating system meets both the letter and the spirit of these regulations."

Major undertaking

The coast-down audits have been a major undertaking for the EPA, which does not own a straight, flat, two-mile-long track needed for the test. Last year the agency used a decommissioned Air Force base in northern Michigan, Grundler said; this year it paid to use the Chrysler proving ground in Chelsea, Mich., 20 miles west of the EPA's vehicle testing laboratory in Ann Arbor, along with two tracks in Arizona.

In their raw form, the test readings would not mean much to the general public. They are coefficients from a mathematical formula, and do not follow a clear pattern, so it is hard to detect cheating without extensive testing.

Grundler said this fall's report will explain the EPA's findings in "plain English."

"That's just consistent with the way I want us to work," he said. "We use public resources to do these tests, and the public deserves access to the work."