WASHINGTON -- The EPA directed Mitsubishi Motors Corp. to provide the agency with additional information on its U.S. vehicles after the automaker admitted to using improper fuel economy tests in Japan for the last 25 years.
An EPA spokeswoman said Tuesday that the agency, coordinating with the California Air Resources Board, also directed the automaker to conduct additional coast down tests on vehicles sold in the U.S. going forward.
A California Air Resources Board spokesman said the agency has also instructed Mitsubishi to provide it with additional information on vehicles sold in the state.
Irregular coast down tests have prompted Hyundai, Kia, Ford and Mercedes-Benz to relabel the fuel economy ratings on several models since 2012.
During the test, vehicles are made to coast to a stop from 80 mph, generating readings on aerodynamic drag and friction in the drivetrain, among other data points.
The data is then used to program dynamometers to simulate a vehicle’s behavior on real roads during laboratory testing.
Mitsubishi said Tuesday that it had deviated from official “coasting test” procedures since at least 1991. The company’s market value has dropped by half since it admitted last week to manipulating fuel economy figures for four minicar models sold in Japan.
The automaker said Tuesday that driving resistance data measured via the improper tests were taken for a “fuel-economy grade” version of the 2014 model year eK Wagon minicar sold in Japan. The model is also supplied to Nissan, which sells it under the Dayz nameplate.
The driving resistance data were then applied to three other versions of the eK Wagon and Dayz models, including four-wheel-drive and turbo versions, instead of data taken from tests of other versions.
Fuel economy calculations for two other models were also based on data measured from the eK Wagon using the improper tests, Mitsubishi said.
It’s unclear how widely Mitsubishi employed such practices. The automaker said it plans to look into models beyond the four minicars already identified this week and will issue a separate report on its findings.
In November 2014, Hyundai and Kia agreed to settle a two-year EPA investigation and pay a $350 million fine after fuel economy ratings on several models were inflated due to inaccurate coast down test data.
Last year, the EPA updated its coast down procedures to ensure greater accuracy in testing, partly in response to the recent errors.