On Friday, South Korea-based automakers Hyundai and Kia - both owned by the Hyundai Motor Group - acknowledged having overstated the gas mileage of their vehicles soled in the US during the last two years.

With both carmakers having sold nearly 900,000 vehicles - approximately one-third of their total sales - in the US over the last couple of years, the one main factor they have been harping on is the `fuel economy' of their vehicles, which they claimed, in a number of ads, to be better than that of their rivals' cars.

However, with an Environmental Protection Agency (EPA) probe into consumer complaints related to gas mileage of Hyundai and Kia cars clearly revealing the underperformance of the vehicles with regard to the official mileage estimates, both automakers have now admitted to their overstatement of better-than-rivals fuel efficiency of their cars.

Extending an apology to the customers for what they termed as "procedural errors" in testing, Hyundai and Kia said they will compensate the consumers who purchased cars with the inaccurate official-mileage stickers, as well as re-state mileage estimates for the affected models, which include the likes of Hyundai Elantra and Kia Rio.

With the compensation for the affected customers to include debit cards to be offered by Hyundai and Kia to refund the difference between the `officially stated' and the `actual' gas mileage of their vehicles, John Krafcik CEO of Hyundai's American operations - said: "Given the importance of fuel efficiency to all of us, we're extremely sorry about these errors."