Mitsubishi Motors
A Mitsubishi Motors dealership is shown in Poway, California July 27, 2015Reuters

Japan has imposed a fine of 480 million yen (about USD 4.2 million) on automaker Mitsubishi Motors Corp (MMC) for conducting improper fuel efficiency tests to show better fuel consumption rates in over 600,000 vehicles.

Also read: Nissan acquires 34% stake in Mitsubishi Motors for $2.2 billion

Japan's Consumer Affairs Agency said in a statement that the fine has been imposed on evidence that the company marketed the cars under inflated fuel economy claims. The product catalogues and websites for vehicles sold by Japan's sixth-largest automaker carried misrepresentations of their fuel economies, in accordance with a goods and services labelling law, reports Reuters.

The fine covers models sold since the law was revised in April, including the eK wagon minicar, the similar Dayz model produced for Nissan Motor Company and the Outlander SUV. "Mitsubishi Motors claimed that ... its products offered a performance which was markedly better than in reality to attract customers, inhibiting their ability to make purchasing decisions based on fact," the agency said in a statement accompanying its investigation.

In a statement, Mitsubishi said it had received the charges order, and would respond appropriately after examination. In April 2016, MMC admitted that it had conducted improper fuel efficiency tests. MMC's reputation came under the scanner after the revelation and the company is still struggling to recover from the cheating scandal. The market value of MMC tumbled since the scandal broke in April.

In May 2016, fellow Japanese car maker Nissan Motor Co Ltd acquired 34 percent equity stake in Mitsubishi for 237 billion yen (USD 2.2 billion). Both the companies announced that it will cooperate in areas such as purchasing, common vehicle platforms, technology-sharing, joint plant utilisation and growth markets, in a statement.