Hyundai and Kia overstated mileage on 13 models — a $395M correction

In November 2012, Hyundai and Kia conceded that the fuel-economy ratings on about 900,000 vehicles from the 2011–2013 model years were overstated. The EPA's audit testing had found errors on 13 models: ratings were revised down by one to two miles per gallon on most affected cars, and by as much as six on some. The companies' fleetwide average for 2012 fell from 27 mpg to 26 — a single mile per gallon, printed on every window sticker, that the cars had never earned.

The correction cost up to $395 million: reimbursement to owners and lessees for the extra fuel the overstated ratings had promised to save. The EPA's follow-on settlement in 2014 added a $100 million civil penalty and $250 million in greenhouse-gas credit forfeiture and compliance spending — the regulatory bill on top of the consumer one.

Fuel economy is a number a buyer cannot verify at the dealership; it is trusted from the label. Hyundai and Kia had built their American ascent on exactly that number. Overstating it by a mile per gallon did not just miscalculate a refund — it spent the credibility their whole market position stood on.