The 2012 Hyundai Elantra is one of the vehicles with inflated fuel economy estimates.

After an investigation by the Environmental Protection Agency about overstated fuel economy ratings, Hyundai and Kia will change the labels on about 900,000 cars and SUVs to reflect the correct estimates and voluntarily reimburse owners for the discrepancy.

The discrepancies range from one to six mpg on Hyundai and Kia vehicles from model years 2011 to 2013. The largest reductions in fuel economy are found on the 2012 and 2013 Kia Soul. The 2.0-liter Soul Automatic goes from 26/34 mpg city/highway to 23/28 mpg, while the 2.0-liter Soul Eco drops from 27/35 mpg to 24/29 mpg.

The investigation began after customers complained to the EPA that Hyundai and Kia vehicles were not returning their advertised gas mileage.

Both Hyundai and Kia have created websites where owners can see if they bought a new vehicle with an incorrect window sticker and see if they are eligible for the reimbursement. Owners can visit or and enter the vehicle identification number (VIN). Forbes reports that the reimbursement “amount will be determined based on the number of miles driven and average local gasoline prices, and will be issued in the form of a personalized debit card.”

The debit card will also include a 15 percent bonus from Hyundai or Kia for the “inconvenience” the overestimated fuel economy ratings have caused shoppers, according to the Chicago Tribune.

In addition to owners who bought the affected vehicles new, consumers who bought used Hyundai or Kia vehicles may also be entitled to a reimbursement. “Hyundai and Kia officials tell us you're still eligible to receive the debit card if you bought it before today's announcement,” Kicking Tires reported Friday. “We assume you'll need the bill of sale to show mileage at the time of purchase.”

For a full list of affected vehicles, click here.

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