On Tuesday, Mitsubishi Motors announced that it has been using testing methods for fuel economy that did not comply with regulations in Japan for the past 25 years. That was much longer than originally thought. The automaker said it would investigate the matter by using an external committee.

The sixth largest Japanese automaker has lost over half its market value or approximately $3.9 billion since last week when it admitted it had overstated fuel economy of four mini-vehicles, domestic models, that includes two that were manufactured by Nissan Motor Co.

The admission by the automaker that more of its models might not comply with standards set in Japan, has sparked many fears of ballooning fines and compensation costs.

The auto safety regulator in the U.S. is also asking for information, while authorities in Japan raided one of the automaker’s R&D facilities.

Mitsubishi said it would set up a committee of experts unaffiliated with the company that would report their results of an investigation that would take three months.

The automaker said that it had been compiling data for tests on fuel economy using standards in the U.S., where highway driving in more common where higher speeds are maintained, rather that standards from Japan, which are set up to reflect driving in the city, which means more stops and often times means additional fuel is used.

On Tuesday, the company released a statement saying it submitted data that was non-compliant to the transport ministry of Japan since 1991.

Mitsubishi previously had said it only handed over such data that was non-compliant since 2002.

The transport ministry earlier on Tuesday announced that it set up a separate task force in order to examine how fuel economy data was submitted by other automakers.

The ministry last week ordered other automakers that were domestic to submit test data on fuel economy on or before May 18.

The misconduct revived the memories of a huge scandal 15 years ago. In that scandal, Mitsubishi admitted it had systematically covered up customer complaints of over 20 years.

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