Hyundai, Kia Gas Mileage Lawsuit - Two years after the Korean carmakers claimed overstating vehicles' fuel economy ratings, Hyundai and Kia will need to pay the U.S. government with $350 million in penalties.

Hyundai and Kia's gas mileage lawsuit penalty of $350 million is said to be the highest settlement in the history of Clean Air Act, said officials on Thursday, as reported by Reuters.  

The penalties come on top of the amount agreed by the automakers to pay the owners of the vehicles. Last December, the two automakers agreed to pay $395 million to resolve claims of the vehicle owners bringing the total cost of more than $700 million for Hyundai, Kia gas mileage lawsuit.

Hyundai and its affiliate, Kia Motors Corp., were accused of selling 1.2 million cars and SUVs that didn't meet the emission claims they made to U.S. Environmental Protection Agency (EPA) and of exaggerating the true fuel economy of many of those vehicles by one to six miles per gallon. These vehicles include 2012 and 2013 versions of Hyundai Accent, Elantra, Veloster, Santa Fe and also Kia Rio and Soul.

As a result, the government explains that these vehicles will emit 4.75 million more metric tons of pollution. The greenhouse gas emissions that the lost credits would have permitted are equal to the emissions from powering more than 433,000 homes for a year, the EPA said.

Monday's settlement with EPA, U.S. Department of Justice and the California Air Resources Board resolves the investigation of the 2012 Hyundai and Kia gas mileage lawsuit.

"This will send an important message to automakers around the world that they must comply with the law," said Attorney General Eric Holder.

The Hyundai, Kia gas mileage lawsuit made the companies to send statement that it believes its process for testing vehicle fuel economy meets U.S. standards, and the overstatement was just a result of data processing error.