Engineering news
Mitsubishi Motors has admitted to using fuel consumption tests that have broken Japanese rules since 1991.
The further admission follows an internal investigation of the manufacturer after it was discovered it had falsified fuel economy data for more than 60,000 vehicles in Japan.
As a result of the admission of manipulating test data for four mini-vehicle models, the manufacturer has lost half its market value – some £2.7 billion.
Mitsubishi has also admitted that more models may have used tests that did not comply with Japanese standards, prompting concern about ballooning potential compensation costs and fines.
Mitsubishi's fuel economy tests deviated from Japanese standards from 1991 onwards. Specifically, the company neglected to update how it conducted coasting tests, in which a car slows to a standstill to measure its air resistance and drag.
Ryugo Nakao, executive vice president, said Japanese regulations changed in 1991 to require testing methods to better reflect stop-and-go urban driving, but Mitsubishi did not follow that rule change. “We should have switched, but it turns out we didn’t,” he said.
The manufacturer has said it compiled data for fuel-economy tests using US standards, where higher-speed highway driving is common, rather than Japanese standards, where more prevalent city driving routinely consumes more fuel.
While some progress has been made in investigating the events, Mistubishi said in a statement that it will continue to work to discover the causes of the improper conduct and who is responsible.
The statement says: “Sufficient investigation has not been made into MMC vehicles other than the mini-cars described above; we plan to submit a separate report after looking into those models.”
Last week, Mitsubishi said it had manipulated data for four models of cars: the eK Wagon and eK Space, (manufactured and sold by Mitsubishi), and the Dayz and Dayz Roox, (manufactured by Mitsubishi and supplied to Nissan). Production and sales of all four models have now stopped.
Nakao said: “We found that with respect to the fuel consumption testing data submitted to the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), Mitsubishi Motor Company (MMC) conducted testing improperly to present better fuel consumption rates than the actual rates; and that the testing method was also different from the one required by Japanese law. We express deep apologies to all of our customers and stakeholders for this issue.”
The company says it will be looking to see what other vehicles were affected by improper testing, and has established a committee staffed by external experts to investigate the matter.