8/28/2012 DETROIT

Corporate Average Fuel Economy, or CAFE, gradual increases to 35.5 m.p.g. by 2016 and then 54.5 miles per gallon for the 2025 model year

reduce their oil consumption by 12 billion barrels over the course of the program. “

save Americans $1.7 trillion in fuel costs, resulting in an average savings of more than $8,000 a vehicle by 2025.

The fuel savings, he said, would easily exceed the estimated $2,000 to $3,000 that the more efficient vehicles would cost consumers to buy.

The administration also said the rules would cut greenhouse gas emissions in half by 2025, eliminating six billion tons over the course of the program.

Thirteen major automakers, including General Motors, Ford and Chrysler, endorsed the new standards during lengthy negotiations last year.

Auto companies are expected to take different approaches to meeting the more stringent guidelines.

Some, like the Japanese automaker Nissan, are counting on consumers gravitating to all-electric models like its Leaf. Others, like Chrysler, will focus their efforts on improving engines and transmissions on traditional gasoline-powered cars.

Even if the 54.5 m.p.g. goal is reached, most cars and trucks will get lower mileage in real-life driving. Credits for air-conditioning units in vehicles will reduce the average mileage to about 49 m.p.g., and actual driving conditions could reduce it further.