Mitsubishi Motors has been told to stop selling eight of its models while it submitted correct fuel economy readings.
The investigation was launched by the transport ministry after the firm admitted to falsifying the fuel efficiency of two of its models, along with two more cars produced for Nissan.
The latest models affected by the scandal include variants of the Pajero, Outlander and RVR.
In a statement, the transport ministry said: “Our investigation confirmed that the fuel economy on eight models were as much as 8.8 per cent and on average 4.2 per cent lower than advertised.”
Some $3bn was wiped off the firm’s market value in April when it first admitted to rigging tests.
Mitsubishi Motors now forecasts further losses, marking the first fall in profit since the 2008 financial crisis.