TOKYO • Suzuki Motor used the wrong methods to test the fuel economy of its cars in Japan, it said yesterday, widening a testing scandal that has already rocked smaller rival Mitsubishi Motors.
Japan's Transport Ministry ordered widespread checks of industry methods after Mitsubishi Motors admitted last month that it manipulated fuel economy data for at least four mini-vehicle models, overstating their efficiency.
Mitsubishi Motors president Tetsuro Aikawa said yesterday he would step down over the scandal, becoming the first senior departure since it broke, battering the company's reputation and wiping billions off its market value.
Worries over similar damage for Suzuki sent shares in Japan's fourth-largest carmaker down as much as 15 per cent during the day.
Suzuki said it would continue selling its mini-cars and saw no impact on its earnings. The correct readings, it said, were not significantly different from those it submitted.
The Japanese authorities, however, asked for more details from Suzuki before May 31, calling its use of non-compliant tests "outrageous".
"The company apologises for the fact that we did not follow rules set by the country," Suzuki chairman Osamu Suzuki told reporters, saying 2.1 million vehicles were affected.
The company blamed the decision to cobble together readings from individual car parts - rather than a single reading - on its windy testing location on a coastal hill that made readings erratic. The individual parts were tested indoors, it said.
Suzuki specialises in mini-vehicles that have engines of up to 660cc and get preferential tax treatment under Japanese law. It has roughly a third of the country's mini-vehicle market.
Mitsubishi Motors' admission that it cheated on fuel economy tests is its third major scandal in under two decades, and has prompted it to agree to sell a one-third controlling stake to Nissan Motor.
Emissions and fuel economy have come under increasing scrutiny from regulators globally after Volkswagen admitted last year that it used "defeat devices" on 11 million diesel vehicles to lower emissions during tests.