TOKYO (Reuters) - Mitsubishi Motors Corp <7211.T> used improper fuel economy data for additional models that are no longer being sold and plans to report on the matter soon to Japan's transport ministry, local media reported on Wednesday.

Mitsubishi Motors in April admitted to overstating the fuel economy on four of its mini-vehicles, including two produced for Nissan Motor Co <7201.T>, and has said its own investigations suggest that improper mileage calculations were used for nine other models.

The Asahi newspaper said Mitsubishi Motors falsified data for three additional models. The Yomiuri newspaper said the automaker made theoretical calculations for the mileage of more than 10 additional models no longer on the market.

Mitsubishi Motors declined to comment on the reports, saying that the investigation into the issue was ongoing.

The mileage scandal prompted the automaker to restate past earnings, shake up management and sell a controlling stake to Nissan Motor Co Ltd <7201.T>.

(Reporting by Naomi Tajitsu; Editing by Michael Perry)