WASHINGTON (AP) -- Cars and trucks averaging 62 miles per gallon? Seems extraordinary now, but the government suggested Friday that automakers could be required to build new lineups by 2025 that make today's high-mileage hybrids seem conventional and turn gas guzzlers into relics of the past.
It's all included in potential efficiency ranges the government is considering for new cars and trucks starting in 2017. By a decade and a half from now, in 2015, a carmaker's fleet of new vehicles may need to meet a standard somewhere from 47 mpg to 62 mpg, the Transportation Department and Environmental Protection Agency said.
Those mileage gains that would be the equivalent of an annual decrease in carbon dioxide emissions per mile of 3 to 6 percent.
The new standards, while several years away, are closely watched by the auto industry as it develops future vehicles and environmental groups trying to curb oil dependence and reduce greenhouse gas emissions. President Barack Obama has pushed for tougher fuel efficiency standards, and new rules could take on added significance if Congress is unable to pass energy legislation capping greenhouse gases blamed for global warming.
The government envisions gas-electric hybrids making up about half the lineup of new vehicles under the most aggressive standards, while electrics and plug-ins would comprise about 10 percent of the fleet.
After little progress during the past three decades, rules adopted earlier this year will lift the new vehicle fleet average to 35.5 mpg by 2016, an increase of more than 40 percent over current standards.
The administration's release on Friday of a technical analysis started the work on mileage standards for the 2017-2025 model years. The government intends to issue a proposal in September 2011 and a final rule by late July 2012.
The administration wants to "keep the momentum going to make sure that all motor vehicles sold in America are realizing the best fuel economy and greenhouse gas reductions possible," said Transportation Secretary Ray LaHood.
EPA Administrator Lisa P. Jackson said the next round of mileage standards "will accelerate the environmental benefits, health protections and clean technology advances over the long term."
Fuel efficiency standards are designed to improve gas mileage across each automaker's lineup and across the nation's entire fleet of new vehicles. Vehicles must meet differing standards based on their dimensions. Compact cars must get better mileage than sport utility vehicles, for example, but requirements for all types of vehicles will go up.
Friday's "notice of intent" provides an overview of the possible standards, describes the technologies that would be needed to achieve the goals and seeks feedback from the public. The two federal agencies plan to issue a second notice by Nov. 30 with an updated analysis of potential efficiency targets.
Environmentalists have sought requirements of at least 60 miles per gallon by 2025, arguing that more gas-electric hybrids, electric vehicles and cars and trucks with improved internal combustion engines and reduced weight could dramatically alter the cars and trucks Americans drive.
"The auto industry has 15 years to meet these new standards — that's plenty of time to use innovation and technology to reach 60 miles per gallon," said Brendan Bell of the Union of Concerned Scientists' clean vehicles program.
Several states sided with the environmental groups. Governors from eight states — New York, New Mexico, Maine, Oregon, Maryland, Pennsylvania, Massachusetts and Washington — urged Obama in a letter Friday to set standards of 60 mpg by 2025.
Automakers, who plan their vehicle offerings years in advance, cautioned that pushing gas mileage standards up too quickly could force them to raise prices beyond the reach of many consumers.
Dave McCurdy, head of the Alliance of Automobile Manufacturers, which represents General Motors, Ford, Toyota and others, said many of the assumptions "are based on very preliminary and incomplete data at this point and inevitably will change as more information is brought to the process."
The Association of International Automobile Manufacturers, whose members include Toyota, Nissan, Honda and others, said the regulations need to balance issues such as environmental objectives, costs and meeting the needs of customers.
The documents estimate that the toughest efficiency standards under consideration would add up to $3,500 to the price of each vehicle. But under that scenario, owners would recoup their investment in three to four years and save up to $7,400 over the vehicle's lifetime.
If met, the targets would bring strong fuel efficiency to a larger number of vehicles. For example, a new Toyota Prius gets 50 mpg in city-highway driving combined and a Honda Civic hybrid gets 42 mpg in combined driving — figures that would become much more common in 15 years.
Later this year, General Motors and Nissan will begin releasing mass-market plug-in electric hybrids and electric cars that get even better gas mileage, opening a new wave of options.
Parts suppliers who make the batteries, engines and other components are already planning for the changes. "Weight is the enemy of efficiency and that's why vehicle weight — not vehicle size — must be reduced significantly," said Randall Scheps, chairman of the Aluminum Association's transportation group.
U.S. Environmental Protection Agency: http://www.epa.gov/
National Highway Traffic Safety Administration: http://www.nhtsa.gov/