On a recent trip from Detroit to Chicago in a Kia Soul 2.0, I couldn’t quite get 30 miles to the gallon, despite an EPA highway rating of 34. It turns out I wasn’t alone. Hyundai and Kia have now admitted to a “procedural error” in their testing, and will be compensating owners.

How might this happen? Well, the EPA actually tests few vehicles. Instead, it relies on manufacturers to perform most of the testing themselves. If enough owners complain, the EPA will test the car. Owners of the Hyundai Elantra complained, the EPA tested the Elantra, and their results didn’t match Hyundai’s.

All of those models Hyundai and Kia have been claiming get 40 mpg highway? They don’t anymore. In most cases, the new numbers are only one or two mpg lower. (Full list in the press release.) But that Soul 2.0 I drove? Its EPA highway rating has dropped from 34 to 28, now matching what I observed.

Hyundai and Kia will be compensating owners based on the number of miles they drive for as long as they own their cars, adding 15 percent for the inconvenience. They deserve some credit for promptly admitting the errors and offering fair compensation. But it would have been better if they hadn’t cheated the numbers in the first place.