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The 54.5 mpg standard came from the Obama administration’s quest to cut carbon dioxide emissions nearly in half by 2025. The gas mileage is what’s needed to make that cut. Then there were negotiations between the Obama administration, automakers, environmentalists, California and union autoworkers to come up with the final rules.

The rules are tough, but General Motors, the largest U.S. car company, will roll out features to comply, spokesman Greg Martin said.

“Consumers want higher fuel efficiency in their cars and trucks, and GM is going to give it to them,” he said.