General Motors Corp. is promising to cut carbon dioxide emissions from its North American manufacturing plants 40% by 2010, as compared with 2000 levels.

GM is setting the target as part of a voluntary partnership in the U.S. Environmental Protection Agency’s Climate Leaders program.

The auto maker says the reduction amounts to 5 million tons (4.5 million t), equivalent to the emissions generated in powering 432,692 U.S. households.

GM was a founding member of the Climate Leaders program in 2002, when it pledged to cut CO2 10% by 2005, based on 2000 levels. It surpassed that goal, cutting emissions 11.7% in 2003. Today, emissions are 25% below 2000 levels, equivalent to a CO2 reduction of 3.3 million tons (3 million t), GM says.