Fuel economy is measured using a complex standardized test procedure created by the Society of Automotive Engineers and specified by federal regulations. For the U.S. market, each auto manufacturer is required to test its vehicles and report the results to U.S. Environmental Protection Agency (EPA).

Our fuel economy rating adjustments are the result of procedural errors during a process called “coastdown” technique at the joint Hyundai/Kia testing operations in Korea.

Coastdown technique testing measures aerodynamic, tire rolling resistance and drivetrain frictional losses and other factors to generate data used on a dynamometer to calculate EPA’s MPG ratings.  Our internal evaluation revealed that our testing operation implemented changes to our coastdown techniques with the intent of increasing the reliability and repeatability of the underlying data.

Some of these procedures created problems that led to overstated fuel economy ratings for select Kia vehicles. Following discussions with EPA we have taken immediate actions upon determining those errors to make the necessary rating changes and process corrections, including relabeling of affected vehicles currently in dealers’ inventory.

For more information on coastdown testing, please click here.