Subaru Corp. said in a report to the government Friday that mileage and emissions data for 903 new cars were systematically rigged at one of its plants and that the malpractice may have started around 2002.
The revelation is yet another blow to the carmaker, which admitted late last year that unauthorized staff had conducted inspections on new cars, triggering a massive domestic recall.
Still, Subaru denied it had quality-control problems, claiming the vehicles in question satisfied regulatory standards under the original inspection data.
The report was submitted by Subaru President Yasuyuki Yoshinaga to Tetsuya Okuda, director-general of the transport ministry's Road Transport Bureau.
Since any inspection data manipulation will cause public distrust of automakers, "such wrongdoing should never happen," Okuda said, urging Subaru to comply fully with regulations.
"I apologize from the bottom of my heart for causing so much concern and trouble," Yoshinaga told a news conference after the report was submitted.
Yoshinaga vowed to enforce preventive measures. "This is a serious compliance issue. I deeply regret (what happened.)"
In the report to the ministry, Subaru said the misconduct affected all of its nine models, including the Forester sport utility vehicle, as well as Toyota's 86 sports car, which Subaru manufactures.
Subaru said it has no plans for a recall as no quality issues have been found.
The data-rigging was conducted during final testing of new cars at Subaru's Ota plant in Gunma Prefecture, on the orders of the head of the inspection staff, the carmaker said. The malpractice was continued by later employees.
Subaru continued the data fabrication even after a similar scandal engulfed Mitsubishi Motors Corp. in 2016, although some employees at the plant said they should stop it, according to the report.