Mitsubishi Falls On The Sword And Admits Rigging Fuel Economy Tests With Falsified Data

Mitsubishi Motors has fessed up to "improper conduct in fuel consumption testing" for hundreds of thousands of vehicles spanning four minicar models sold in Japan over the past several of years. The motor company intentionally manipulated the testing method that's required for certification by Japanese law so that it could advertise higher fuel efficiency for certain model vehicles.

Affected minicar models include the eK Wagon and eK Space, both manufactured and sold direct by Mitsubishi, and the Dayz and Dayz Roox, which Mitsubishi built and supplied to Nissan Motors Corporation. Over 600,000 vehicles were affected by Mitsubishi's impropriety, including 157,000 it sold direct to consumers and another 468,000 it supplied to Nissan from June 2013 to March 2016.

Mitsubishi eK Wagon

The inaccurate fuel efficiency numbers were discovered by Nissan when it examined the figures of Mitsubishi's next-generation minicars against its reference data. Nissan reported the deviations it found to Mitsubishi, which in turn launched an internal investigation that uncovered foul play in its testing process.

Mitsubishi found that it had been using a running resistance value based on tire and air resistance during testing to arrive at a more favorable gas mileage rating, and that the improper testing was intentional. The testing method it used is different than the one that's required in Japan.

"We have decided to stop production and sales of the applicable cars. Nissan Motors also has stopped sales of the applicable cars, and Mitsubishi Motors Corporation and Nissan Motors will discuss compensation regarding this issue," Mitsubishi said.

This isn't the sort of thing that instills confidence in buyers, and unfortunately Mitsubishi isn't the only one to have gamed the system. Volkswagen AG is perhaps the biggest example of an automaker caught cheating on emissions tests, but others have been accused of overstating fuel efficiency as well. In 2014, Hyundai and Kia agreed to pay $350 million to settle a suit alleging fudged fuel efficiency numbers.

As for Mitsubishi, it's expanding its investigation to see if vehicles manufactured for overseas markets might also be affected.