Japanese automaker Mitsubishi has admitted manipulating fuel economy data related to some 625,000 vehicles. The company announced the news at a press conference this morning, apologizing for the deception and saying it is investigating the employees involved. The manipulated data covers four vehicle models that fall under the Japanese category of kei car. This is a classification that covers minivans, trucks, and passenger cars, but is reserved for vehicles that meet economical fuel consumption standards and are consequently taxed at a lower rate.

The models affected include the eK Wagon and eK Space, manufactured and sold by Mitsubishi, and the Dayz and Dayz Roox, manufactured by Mitsubishi and supplied to Nissan for sale. According to Mitsubishi, it was Nissan's in-house testers that discovered the discrepancy between the cars' published fuel efficiency data, and their real-life results.

Bloomberg notes that local reports say the tests were cheated by varying the load placed above the vehicles' wheels. Mitsubishi's own statements seem to confirm this, noting that the data was skewed by manipulating air resistance and "rolling resistance" of the cars' tires. Mitsubishi says the data affects some 157,000 eK Wagon and eK Space vehicles, and 468,000 units of the Dayz and Dayz Roox.

Shares in Mitsubishi fell more than 15 percent following the news, removing $1.2 billion from the company's market value. Although the manipulation does not appear to have been on the scale of Volkswagen's emission scandal (which affected some 11 million cars), the news contributes to the atmosphere of distrust over regulations enveloping the automaker industry.

"This may be different from Volkswagen’s issue, but the market has become very sensitive to such kind of news," Tokyo-based analyst Seiji Sugiura told Bloomberg. "It may have a similar impact in terms of sales and the company’s reputation."

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