The Mitsubishi Motors Corporation has withdrawn several mini-cars from sale in Japan after admitting it "conducted testing improperly to present better fuel consumption rates than the actual rates".
The affected models are Mitsubishi's own eK Wagon and eK Space, and the Dayz and Dayz Roox vehicles that Mitsubishi makes for Nissan. Launched in 2013, one of the Dayz's selling points is its low fuel consumption, which qualified it for tax breaks under the Japanese "tax system to promote the diffusion of environmentally friendly vehicles." The testing methods used did not comply with Japanese law, the company explained.
The revelations follow the emissions scandal at Volkswagen, where up to 11 million vehicles around the world were said to have been rigged with emissions cheating software.
The improper testing methods were revealed, Mitsubishi said, when Nissan "examined the fuel consumption rates of the applicable cars for [its] reference and found deviations in the figures".
Nissan asked Mitsubishi to review the cars' running resistance figures – a combined measurement of resistance caused by both tyres and air when a vehicle is in motion – which led to an internal investigation. This revealed "improper conduct" inside Mitsubishi's testing facilities.
Specifically, Mitsubishi said that its test "used the running resistance value for testing which provided more advantageous fuel consumption rates than the actual rates."
The company has stopped production and sales of all affected cars and said it would "sincerely respond" to customers, while also announcing an investigation into cars sold overseas. Nissan has also withdrawn the cars involved.