Following admission of more than two decades of misreported mpg data to Japanese authorities, the U.S. EPA says the company’s cars sold stateside are being scrutinized.

“EPA has instructed Mitsubishi to provide additional information regarding their U.S. vehicles,” said the agency today in response to a query by “The agency will also be directing the company to conduct additional coast down testing for vehicles sold in the U.S. We are coordinating with the California Air Resources Board.”

To date what Mitsubishi has confessed to Japanese authorities pertains to several hundred thousand “kei” cars with 660cc engines sold in Japan.

What specifically the additional information is that EPA is asking of Mitsubishi’s U.S. cars was not disclosed. Coast down testing makes vehicles traveling 80 mph coast to a stop during which time data collected includes aerodynamic drag, powertrain friction, and more. It is used as part of the EPA’s protocols to ensure compliance with U.S. law and has been used by the EPA to enforce changes to mpg ratings by other manufacturers.

Not said by the EPA, is what others including the Consumer Federation of America did effectively say yesterday, and that’s that since Mitsubishi lied in its home market, it could be lying elsewhere, so it is better to check.

Mitsubishi Japanese market M-K Wagon. About three-quarters of the 625,000 estimated cars affected were supplied by Nissan.

Mitsubishi Japanese market M-K Wagon. About three-quarters of the 625,000 estimated cars affected were supplied by Nissan.

The EPA’s statement was given in response to the question, “In light of the unfolding scandal in Japan, can you say if the EPA is investigating Mitsubishi or if it is suspected at all in the U.S. for potential falsification of mpg data?”

The explicit answer was not yes, but the implicit answer is the EPA suspects Mitsubishi enough to respond as stated above.

SEE ALSO: Mitsubishi Admits To Cheating On Japanese Fuel Economy Results For 25 Years

And in any case, the scandal in Japan has made good fodder for headlines given the magnitude of the cover-up.

An estimated 625,000 of Mitsubishi’s Japanese market mini-cars have been implicated. Making matters worse, today Mitsubishi disclosed it had been falsifying data for 25 years, 11 years longer than previously confessed when the scandal broke last week.

Since last week the company’s stock value has been cut in half.

As for the California Air Resources Board, which EPA said it is keeping apprised, an ARB official today said no action at the moment is being taken.

“ARB has no jurisdiction over MPG issues. However, in general, if this information applies to vehicles certified to California emissions standards, ARB will investigate and take appropriate action should there be an impact on compliance with our GHG requirements,” said John Swanton, Office of the Chairman, Communications. “Since its our understanding is that this information only applies to a class of ‘mini’ trucks and vans not sold here, any further comment by ARB at this time would be premature.”

Virtual MPG

In Japan, as in the U.S., the government relies upon automakers on an honor system to accurately report data from dynamometer testing.

Betrayal of trust is never something to make anyone popular, as Volkswagen has also found out since last September when it admitted to cheating devices that tricked global regulators into believing its diesels were clean.

The Mitsubishi cars in question are not being accused of gross violations as has been the case of VW’s diesel cheating, but improprieties that may or may not have led to inaccuracies has been admitted by Mitsubishi.

The Mitsubishi i-MiEV is a converted kei car.

The Mitsubishi i-MiEV is a converted kei car.

Mitsubishi said it broke protocol by fudging some data and by using a method not approved by Japanese regulators, but which is used by carmakers in the U.S.

Data collected factored in variables including wind resistance and tire friction to estimate fuel economy.

It was a matter of convenience and better data collection, Mitsubishi said in giving its reason for foregoing more-involved Japanese testing methods.

This has been going in since 1991, the company said, and in cases fuel economy data for certain vehicles looked better – one report said as much as 10 percent better – in other cases, the company said it did not not improve results.

Mitsubishi President Tetsuro Aikawa offered an apology today, while conceding the automaker which survived an unrelated scandal 15 years ago is again on shaky ground.

“This is a problem that threatens the existence of our company,” said Aikawa.

What its full implications will be for U.S. operations remains an open question.