Hyundai Motors has confirmed it will pay South Korean owners of its Santa Fe SUVs up to 400,000 won per car after the transport ministry determined the fuel economy of the SUV had been overstated.

The news is expected to affect around 140,000 vehicles, meaning the payout could reach a total of 56 billion won ($54.41 million), a Hyundai Motor spokesman said to Reuters.

Kim Woong, a lawyer at the firm Yeyul, which is representing some of the Santa Fe owners, said Hyundai's compensation proposal doesn't meet his clients' demands.

"The proposed amount [from Hyundai] is way too low. We won't drop our lawsuit. We're preparing another group action for about 4,300 customers and will file it with a Seoul court later today," said Kim, according to The Wall Street Journal.

The plaintiffs are seeking damages between 900,000 won and 3 million won ($890 to $2,967) each.

South Korea's transport ministry announced back in June that it will fine Hyundai Motors approximately 1 billion won ($1 million) after its tests confirmed the fuel economy of the  2.0-liter Santa Fe (DM) was 8.3 percent lower than the vehicle's stated figure.

That exceeds the standard margin of error of 5 percent.

Hyundai and sister company Kia Motors said in 2012 that they overstated the fuel economy of about 900,000 vehicles in the United States.

The confession caused the transport ministry to test 14 vehicles sold in South Korea, including the Santa Fe.

The Santa Fe has been in production since May 2012.

Hyundai is planning on changing the official mileage of the model from 14.4 kilometers per liter to 13.8 kilometers per liter, according to a company statement.

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