Ford Motor said it would lower the fuel economy ratings for six vehicles and make goodwill payments to owners of about 200,000 cars.
The action covers all of the automaker's 2013 and 2014 hybrids and plug-in hybrids, as well as the 2014 Ford Fiesta.
In some cases the changes lower cars' combined fuel economy rating by as much as 7 miles per gallon.
Ford said it identified the discrepancies in internal testing and notified the EPA, which then retested the cars to compute the new ratings.
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