The Environmental Protection Agency (EPA) orders Daimler AG to revise its fuel economy ratings for its Mercedes Benz C300 4-Matic.

The luxury sedan from model years 2013 and 2014 is the next car to receive an order for revision after the EPA tested Daimler's estimates for both the Flexible Fuel Vehicle and Partial Zero Emissions Vehicle versions of the C300. Unlike downgrades implemented by other car makers, changes for the C300's fuel efficiency rating are minimal.

For the FFV version, the EPA's estimates peg the C300 at 19 miles per gallon, or only one mile less than Daimler's previous ratings. The highway driving rating, however, remains unchanged at 27 miles per gallon and the average rating is at 22 miles per gallon, the same rating Daimler assigned the C300 before EPA testing.

The PZEV model, on the other hand, received a one-point decrease for its fuel economy rating for city driving, highway driving and the average rating. Previously, the PZEV version had a rating of 20 miles per gallon for city driving and 29 miles per gallon for highway driving. The new ratings are pegged at 19 miles per gallon and 28 miles per gallon for city and highway driving respectively. Overall, the rating for the PZEV C300 took a slight dip from 23 to 22 miles per gallon.

"Even though the adjustments are small, it is important that our oversight system is producing the correct results because even one mpg matters to consumers," says [subscription required] Christopher Grundler, EPA's director of the Office of Transportation and Air Quality, in a statement provided to the Wall Street Journal. "EPA will continue strong oversight of fuel economy values to ensure that consumers have the best information available to make important purchasing decisions, to ensure fair competition among auto makers, and to protect investments in new fuel-efficient technologies."

The EPA independently tests 15 percent of cars and trucks released each year and conducts testing on pre-production models provided by car makers to confirm the fuel efficiency labels used in post-production vehicles. If results of the testing show that the manufacturers overestimated their cars' ratings, the EPA will order them to update their labels with the latest figures.

Earlier in June, the EPA also conducted re-testing on Ford vehicles after the Dearborn, Michigan-based auto maker approached the agency saying that it failed to put into consideration aerodynamics, tire friction and other real-world factors in estimating the fuel economy of its cars. As a result, Ford downgraded the labels for six of its vehicles, including 2013 and 2014 models of the Fiesta, Fusion Hybrid, C-Max Hybrid, Lincoln MKZ, Fusion Energi and C-Max Energi.