Mercedes-Benz will reduce the fuel economy ratings of some MY2013-2014 C-class sedans after the United States Environmental Protection Agency found errors in mpg test procedures. For instance, the MY2013-2014 C300 4Matic with “partial zero emission vehicle” certification will have their city, highway and combined driving mpg ratings will each drop by 1 mpg to 19 mpg city, 28 highway and 22 combined.
A C300 4Matic version fueled by ethanol or gasoline will also have its city rating reduced by 1 mpg to 19 mpg, although its 27 mpg highway and 22 mpg combined will stay as they are. The changes were confirmed by a Mercedes spokeswoman.
The C-class models with revised labels were replaced in August, as Mercedes commenced selling the redesigned 2015 C-class. She added that only around 500 units of the affected units are still on dealer lots.
The mpg rating revision at Mercedes underscores a campaign by EPA in ensuring that carmakers comply with testing protocols and provide accurate mpg information to customers. Other carmakers that EPA has flagged down for errors in testing procedures include Hyundai, Kia and Ford, prompting them to revise mpg ratings on several models.
Christopher Grundler, director of the EPA’s Office of Transportation and Air Quality, said in a statement, that while the mpg adjustments are small, it is important that the agency’s oversight system is producing the correct results since even one mpg matters to consumers.
During its audit, EPA determined that Mercedes underestimated the impact of aerodynamic drag and tire rolling resistance in its fuel economy testing. Its audit showed different mpg results for the C300 than those provided for by Mercedes.