The EPA announced, on February 23, 2015, that it will release new guidelines for vehicle fuel economy testing. The new guidelines will apply next year and will address how vehicles should be prepared and broken in before fuel economy testing. The testing for fuel economy has not been updated in ten years, and the guidelines follow 2011 regulations overhauling fuel economy labels.

The EPA has been actively monitoring vehicle fuel economy ratings in recent years. In 2014, the EPA required the 2014 Mini Cooper 3 Door to update its fuel economy values, Mercedes to relabel the 2013 and 2014 C300 4-matic models, and Ford to re-label four versions of the Ford Fiesta, the Hybrid and Energi versions of the Ford Fusion, the C-Max Hybrid and Energi, and the Lincoln MKZ Hybrid. In the fall of 2014, Hyundai Motor Co. and Kia Motors Corporation agreed to a record-setting combined settlement for overstating fuel economy ratings. The settlement included a $100 million civil penalty, forfeiting over $200 million in regulatory credits.

Although the guidelines do not have the force of formal rule-making from the EPA, the EPA hopes these guidelines will fill gaps in the existing regulations and result in more accurate fuel efficiency numbers. The guidelines may also allow the EPA and manufacturers to more quickly adapt to changes in technology and other issues impacting fuel economy and testing.