Subaru Corp. revealed fresh cases of improper final vehicle inspections on Friday in a final report on its series of data falsifications that blamed excessive workloads on inspectors for causing the practice.

The Japanese automaker has newly found that its inspectors failed to take proper steps in checking brakes and speed meters. The number of affected vehicles is difficult to know as the conduct came to light based on hearings with employees, it said.

Subaru has already been grilled over the earlier finding that its inspectors fabricated fuel and emissions data, which prompted the company to launch an in-house investigation.

The improper inspections, believed to date back to the early 1990s and which first surfaced in March this year, has affected 1,869 vehicles, up from 1,551 announced in June, the automaker said.

Employees who lacked "awareness of norms," as well as "insufficient supervision" by management cased the series of scandals, according to the report, submitted to the transport ministry earlier in the day.

"I sincerely offer apologies for causing great concern and worry," Subaru President Tomomi Nakamura said at the ministry.

(Subaru President Tomomi Nakamura)

In doctoring fuel and emissions data, some inspectors had copied measurements taken from a separate vehicle to meet prescribed testing standards, the report said.

A Subaru plant in Gunma Prefecture, where inspection data were fabricated, was built in the 1960s and lacked proper air conditioning, making it difficult for inspectors to conduct tests in a controlled environment, it also said.

Several inspectors at the plant said that in winter they had to boil water using an electric pot so that humidity levels in the testing room would be maintained within the standards, according to the report.

A group of lawyers who conducted the in-house investigation said that as Subaru had cut investment at the plant, workloads on inspectors there increased.

To prevent a recurrence, Subaru said it will review workloads in the inspection process and also enhance commitment by its executives in ensuring product quality.

Subaru is among several major Japanese companies found to have fabricated product data, including Kobe Steel Ltd. and Mitsubishi Materials Corp.