The U.S. Environmental Protection Agency (EPA) released its latest report on fuel economy trends and carbon dioxide emissions Thursday. The data includes fuel economy ratings through model year 2012 and preliminary data on fuel economy ratings for model year 2013.

Fuel economy increased by 1.2 miles per gallon (mpg) in 2012 compared with 2011, the fourth highest since the EPA began keeping records in the mid-1970s and, at a total fleet average of 23.6 mpg, the highest fuel economy level ever. Carbon dioxide emissions fell by 22 grams per mile to a total of 376 grams per mile, an all-time record low for carbon emissions.

The highest adjusted (as defined by the EPA) fuel economy rating among automakers was achieved by Mazda, with model year 2012 rating on all its cars and trucks of 27.1 miles per gallon. Honda Motor Co. Ltd. (NYSE: HMC) ranked second with an fleetwide rating of 26.6 mpg, followed by Volkswagen at 25.8 mpg, and Toyota Motor Corp. (NYSE: TM) at 25.6 mpg. The best-rated U.S. carmaker’s fleet came from Ford Motor Co. (NYSE: F) with a fuel economy score of 22.8 mpg, followed by General Motors Co. (NYSE: GM) at 21.7 mpg, and Chrysler Group LLC at 20.1 mpg.

Pickup truck and SUV sales at all three U.S. automakers drag down their overall fleet ratings. Ford cars, for example, average 27.2 mpg, while Ford trucks managed just 18.5 mpg. GM’s Chevrolet cars posted a fuel economy rating of 25.7 mpg while Chevy pickups could manage just 18 mpg. Chrysler’s Dodge Ram pickups posted just 16.1 mpg.

Preliminary data for model year 2013 vehicles indicates a gain of 0.4 mpg in overall fuel economy. Ford’s rating for all its cars and trucks is tagged to drop slightly to 22.6 mpg, while GM’s rating is expected to rise to 22 mpg and Chrysler cars and trucks are tabbed to improve to 21.6 mpg.

In carbon dioxide emissions, U.S. automakers performed worse than the 2012 average of 376 grams per mile. Ford vehicles emitted 390 grams per mile while GM vehicles came in at 410 grams per mile and Chrysler was worst of all makers at 442 grams per mile.

Alternative fuel vehicles are also on fuel economy in mile per gallon equivalent (mpge) and carbon dioxide emissions. All electric vehicles like the Nissan Leaf or the Model S from Tesla Motors Inc. (NASDAQ: TSLA) emit no tailpipe carbon dioxide, which a Toyota Prius plug-in hybrid spits out 133 grams per mile and the Ford C-MAX and Fusion models emit 110 grams per mile.

The mileage ratings are based on converting electricity consumption data into an equivalent amount of energy as contained in a gallon of gasoline. For a Tesla Model S with the 85kW-hr battery pack that works out to 89 mpge. The highest rated vehicle is the Scion from Toyota at 121 mpge.

Thank you for reading! Have some feedback for us?
Contact the 24/7 Wall St. editorial team.