The United States Environmental Protection Agency is getting ready to further stiffen its oversight of mpg testing and reporting this year as it bid to make fuel economy ratings much closer to what drivers could experience in real-world driving.
EPA will particularly focus on its "coast-down" test, which has been tagged as the source of mistakes that have prompted carmakers like Hyundai, Kia, Ford and Mercedes-Benz to restate the sticker ratings of a number of models since 2012.
The test entails having vehicles coast to a stop from 80 mph, which generate readings on aerodynamic drag and friction in the drivetrain, as well as other data points. EPA will use the data gathered to program dynamometers to simulate a vehicle's behavior on real roads during laboratory testing.
According to Christopher Grundler, director of the EPA's Office of Transportation and Air Quality, EPA will issue by end of the year revised guidelines on how carmakers should conduct the testing, said. EPA intends to continue stepped-up audits of the carmakers' tests.
Likewise, the agency may compel carmaker to verify their own preproduction testing results using production models.
The revised guidelines are expected to standardize coast-down test procedures, which, according to Grundler, vary by carmakers. EPA has to revise the guidelines after cases of carmakers having to trim mpg ratings due of internal and EPA audits that found errors in coast-down testing.
Grundler told Automotive News in an interview that both the EPA and the auto industry both would want to see label values representing “a good number."