The Department of Transportation (DOT) and the EPA on Thursday, April 1, 2010, jointly established new federal rules that set the first-ever national greenhouse gas emissions standards for passenger cars and light trucks sold in the United States.

Today's final rules, issued by DOT's National Highway Traffic Safety Administration (NHTSA) and EPA, establish increasingly stringent fuel economy standards under NHTSA's Corporate Average Fuel Economy program and greenhouse gas emission standards under the Clean Air Act for 2012 through 2016 model-year vehicles.

Because credits for air-conditioning improvements can be used to meet the EPA standards, but not the NHTSA standards, the EPA standards require that by the 2016 model-year, manufacturers must achieve a combined average vehicle emission level of 250 grams of carbon dioxide per mile. The EPA standard would be equivalent to 35.5 miles per gallon if all reductions came from fuel economy improvements.

Starting with 2012 model year vehicles, the rules together require automakers to improve fleet-wide fuel economy and reduce fleet-wide greenhouse gas emissions by approximately 5 percent every year. NHTSA has established fuel economy standards that strengthen each year reaching an estimated 34.1 mpg for the combined industry-wide fleet for model year 2016.

NHTSA and the EPA expect automobile manufacturers will meet these standards by more widespread adoption of conventional technologies that are already in commercial use, such as more efficient engines, transmissions, tires, aerodynamics and materials, as well as improvements in air conditioning systems, the agencies said in a press release. Some manufacturers may choose to pursue more advanced fuel-saving technologies like hybrid vehicles, clean diesel engines, plug-in hybrid electric vehicles, and electric vehicles.

The EPA received more than 130,000 public comments on the September 2009 proposed rules.

"These historic new standards set ambitious, but achievable, fuel economy requirements for the automotive industry that will also encourage new and emerging technologies," said Transportation Secretary Ray LaHood.