Hino Motors, a truck maker that is part of the Toyota group, systematically falsified emissions data dating back as far back as 2003, according to the results of an investigation.

President Satoshi Ogiso bowed deeply at a hastily called news conference and apologised to customers and other stakeholders.

“I am so deeply sorry,” he said. “Unfortunately, misconduct had been carried out for a widespread variety of models.”

Teams that were developing engines knew they could not meet targets and felt so pressured they falsified test results, Mr Ogiso said.

That led to more deception, as workers covered up their wrongdoing, he added.

Hino acknowledged in March that it had faked data on government required tests on emissions and mileage. A group of outside experts was set up to investigate.

In a 17-page report, it blamed an “inward-looking and conservative culture” at the company that led to a lack of involvement and solidarity among the employees.

The experts told reporters the company’s leadership failed to engage with frontline workers, putting numerical goals and deadlines first and sacrificing operating procedures.

Hino said it takes the findings seriously and will come up with measures to prevent a recurrence, including setting up a proper checking system, revising rules and beefing up corporate culture.

Mr Ogiso promised to educate Hino’s workforce and nurture a more open corporate culture and proper work ethic, stressing the problem was company-wide, not just with the teams in question.

“I am determined to see that we are reborn, and we carry that out in clear action,” said Mr Ogiso, who formerly worked at Toyota, Japan’s top car maker.

The unearthed misconduct included altering durability tests related to emissions on a wide range of models and tampering with fuel efficiency information in heavy-duty engines.

Hino has recalled 67,000 vehicles in Japan related to the wrongful data. How Hino’s financial results will be affected by the latest disclosure is still unclear, Mr Ogiso said.

Whether he, as well as past executives, will resign to take responsibility will be decided later after a full review of the scandal, he said.

Regarding models sold abroad, Hino said it was cooperating with investigations by authorities in the US and Europe.

Hino produces vehicles sold under the Toyota brand, including the Land Cruiser Prado sport utility vehicle, in addition to Hino trucks. Hino has notified the Japanese government about the findings.

The scandal at Hino, 50.1% owned by Toyota, is the latest among many that have proved an embarrassment for a country that prides itself on a reputation for discipline, craftsmanship and attention to detail.

In 2018, Suzuki, Mazda and Yamaha Motor Co admitted to falsifying emissions data, shortly after Nissan and Subaru acknowledged similar misconduct in their fuel-economy data.

In 2015, an investigation into Mitsubishi found extensive cheating on mileage data over 25 years.

The car maker had admitted to a cover-up in the early 2000s of vehicle defects such as failing brakes, faulty clutches and insecurely installed fuel tanks. That misconduct had begun in the 1970s.