In 2012, Hyundai decreased the gas mileage estimates on around a quarter of its 2011, 2012 and 2013 model year vehicles, and established a program to reimburse owners for the difference between calculated gas costs for the two mileage estimates. At the time of the readjustment, Hyundai introduced a lifetime reimbursement program, which provided a lump sum reimbursement for miles already driven, and regular future payments for the life of the car, plus an extra 15 percent for the inconvenience.
As an alternative to the lifetime reimbursement program, and after a class action lawsuit, Hyundai also offered customers either a one-time lump sum payment, a dealership credit worth 150 percent of the lump sum payment, or a credit towards the purchase of a new Hyundai worth 200 percent of the lump sum payment. As of September 2015, customers can no longer enroll in Hyundai's reimbursement program.
Hyundai decreased its gas mileage estimates as the result of an investigation by the U.S. Environmental Protection Agency in response to customer complaints about Hyundai gas mileage. Hyundai contests that the gas mileage differences were due to simple procedural errors, and not an intentional attempt to mislead. In addition to customer reimbursement, Hyundai had to pay the United States federal government roughly $300 million, $100 million in cash and about $200 million in foregone greenhouse-gas emission credits.