U.S. Issues Limits on Greenhouse Gas Emissions from Cars

This past week the federal government took its first formal step to regulate global warming pollution, by issuing final rules for greenhouse gas emissions for automobiles and light trucks. This includes new tailpipe rules, jointly written by the Transportation Department and the EPA, setting emissions and mileage standards that would translate to a combined fuel economy average for new vehicles of 35.5 miles per gallon by 2016. These rules are expected to cut emissions of carbon dioxide and other heat trapping gases about 30% from 2012 to 2016. This is the first time the federal clean air act has been applied to carbon dioxide and other global warming pollutants.

http://www.nytimes.com/2010/04/02/science/earth/02emit.html?ref=science