The Japanese government says Mitsubishi Motors Corp. overstated mileage on its vehicles by up to 16 percent.

The transport ministry said Tuesday it did its own mileage tests to look into the cheating by the Japanese automaker on its minicar models, tiny cars eligible for tax breaks in Japan.

Tokyo-based Mitsubishi Motors acknowledged recently it had systematically inflated mileage for eK minicar models, as well as some other models. But it has said it did not lie on mileage on models sold abroad.

Last month, Nissan Motor Co. took a 34 percent stake in Mitsubishi, promising to help a turnaround. Under a special agreement, Mitsubishi had supplied the models to Nissan, which does not make its own minicars. Nissan's own tests had uncovered the mileage cheating.