Aug. 9 (UPI) -- Japanese automakers Mazda and Suzuki and motorcycle company Yamaha have acknowledged running improper fuel economy and emissions tests after the transport ministry ordered an investigation last month.
The Ministry of Land, Infrastructure and Transport said Thursday all three companies reported "inappropriate handling" of vehicle inspections.
The probe comes after a ministry request for all Japanese automakers to investigate compliance procedures after findings earlier this year that Nissan Motor and Subaru falsified data.
Suzuki admitted to conducting the largest number of improper tests, 6,401 units out of 12,819 since 2012. Mazda spotted inapt testing on 72 vehicles out of 1,875 since 2014 and Yamaha found seven cases out of 335 since 2016.
On Thursday, stock prices of all three companies took a dive, and at one point Suzuki and Yamaha shares fell by more than 5 percent.
In lieu of the findings, the transport ministry is changing its ordinance to request automakers save test results and take measures to prevent altering the results.
"It is extremely regrettable that this situation makes users anxious over the quality of vehicles and the quality control operations of carmakers," said Transport Minister Keiichi Ishii.
During a news conference Thursday, Suzuki President Toshihiro Suzuki apologized.
"It is a significant fact that such a large number of our products were improperly processed, and we take it seriously," Toshihiro said. "We failed to educate our staff in an in-depth and extensive manner."
Mazda declined to comment about the findings but said it would issue a statement later Thursday.