Beleagured automaker Mitsubishi Motors Corporation (MMC), which is struggling in the wake of a deepening fuel economy scandal, has issued a summary of its report submitted to the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), pursuant to instructions received from the ministry on April 20 to investigate and report on the matter.

The automaker said that investigations reveal that its improper manipulation of running resistance to present better fuel consumption rates began with the development of the fuel-economy grade for the model year 2014 Mitsubishi eK Wagon and Nissan Dayz, when running resistance for other grades (standard grade, turbo grade, 4WD grade) as well as for the eK Space and Dayz Roox and each model year change were simulated using testing data only from fuel-economy grade variants.

During the development of the fuel-economy grade variant, the fuel consumption target was raised a total of five times, from 26.4km/L to 29.2km/L. This revision in numbers progressed – in response to keeping up with competitors’ fuel economy levels – even though realistic attainment of the targets was, as it put it, “problematic.”

Mitsubishi said the testing coordinators at the time were well aware that fuel consumption meant “the factor that would give the most product marketing appeal,” and thus felt that the fuel consumption improvement targets requested by managers and executives were absolute.

It added that administrative managers in development-related departments didn’t communicate these reservations and so didn’t confirm the real situation, even though they understood that the problematically high fuel consumption targets were difficult to achieve.

Internal hearings suggest that running resistance was improperly calculated in nine other models currently sold in Japan as well as in other models no longer sold in the country. The use of desktop calculations is also suspected, and investigations into the background and details are ongoing and will be announced separately.

Last month, MMC announced the establishment of a special investigation committee – consisting entirely of external experts – to investigate the matter over the next three months. A report will be disclosed once the committee has obtained its findings.

Earlier today, it was reported that Nissan was in talks with Mitsubishi to purchase a one-third stake in the latter. If the deal does goes through, Nissan – Japan’s second largest carmaker – would become the largest single shareholder in MMC.