( CNN ) -- The federal government may require automakers to road test cars to ensure the accuracy of gas mileage claims , the Environmental Protection Agency confirmed Tuesday . Currently , the EPA road tests 10 to 15 percent of new vehicles every year , but the other 85 % are tested by the car companies themselves , typically through use of computer modeling , wind tunnels and treadmill-like tests . But those methods have come under scrutiny . Korea 's Hyundai and Kia lowered fuel economy estimates for some 2012 and 2013 models after the EPA found discrepancies between agency results and data submitted by the company . Mileage claims were lowered by 1 or 2 miles per gallon on most cars , but the Kia Soul was adjusted by 6 miles per gallon . And Ford last month agreed to make a `` goodwill payment '' to owners of 2013- and 2014-model year hybrid vehicles and most 2014 Fiestas after the EPA challenged its mileage claims . The answer , the EPA says , is to require car makers to conduct road tests . `` Some automakers already do this , but we are establishing a regulatory requirement for all auto makers , '' Chris Grundler , director of the EPA 's Office of Transportation and Air Quality , told the Wall Street Journal . The proposal has not been formalized , and would have to go through a lengthy public comment and review period . `` At this early stage , it is premature for us to speculate on what form a proposal may take , '' the agency said in a statement Tuesday . `` EPA will engage interested stakeholders proactively before making any proposal . '' The EPA said the wind tunnel and other tests are important to get repeatable , reliable data . But it said it is considering requiring road tests . The Obama administration has pushed through significant changes in auto mileage requirements for passenger cars and light trucks , including SUVs , pickups and minivans , as a way to reduce U.S. oil consumption . Related policies and consumer demand with gas prices going up have led to design changes , lighter vehicles , cleaner-burning engines and more gas-electric hybrid vehicles . Cars that go further on a gallon of gas are also a big selling point with consumers looking to save money at the pump .
The EPA has challenged some car companies on their gas mileage claims . EPA road tests only a fraction of vehicles , while car companies basically use other methods . Comment: Consumers have responded , driven by saving money at the pump .