President Barack Obama unveiled a government push on Friday to boost auto fuel economy for model-year 2017 passenger vehicles and beyond, and introduce a truck efficiency target for the first time.
Obama's policy initiative was characterized by leading environmental groups as an especially welcome step in the wake of the BP Gulf Coast oil spill.
"I believe it's possible in the next 20 years for vehicles to use half the fuel and produce half the pollution that they do today," Obama said at a White House ceremony.
Separately, Canada announced similar steps for heavy trucks and hopes to propose a draft regulation within several months.
Cars and trucks account for more than 60 percent of U.S. oil consumption and more than 25 percent of domestic carbon pollution, environmental statistics show.
David Doniger, policy director for the Climate Center at the Natural Resources Defense Council, said tougher standards for cars and the first-ever efficiency goals for trucks will save consumers billions of dollars in fuel costs.
"These are important steps to cut our oil dependence and carbon pollution," Doniger said in a statement.
The new rules for passenger cars, sport utilities, pickups, and vans will be carried out by transportation and environmental regulators.
California, a leader in the effort to curb vehicle emissions, will play an important role in developing an efficiency framework for the rule that will run from 2017-25.
The Obama administration in April completed regulations for passenger vehicles that will require a 30 percent decrease in carbon emissions and a 42 percent increase in auto fuel efficiency to 35.5 miles per gallon by 2016.
Automakers sought assurances in recent weeks that the Obama administration would seek to extend federal oversight of those standards beyond the 2016 time frame.
Industry believes anything less than a firm government commitment on the subject would open the door to competing state standards that could vary from region to region, complicate product planning and add heavy costs.
But trying to gauge long-term fuel efficiency targets for 2017-25 could be trickier than past efforts that were strictly tied to gasoline use.
Industry has embraced cleaner burning fuels, more efficient engines and advanced battery technologies for gasoline-electric hybrids and full-electric cars that produce few to no emissions.
Automakers are moving fast to boost efficiency, and many cars on the road already meet or exceed the 2016 targets. General Motors and Japan's Nissan are racing to roll out the first mass-produced electric cars later this year and other manufacturers have designs in the pipeline.
The administration has provided important incentives to jumpstart production of vehicles that are powered by advanced technologies.
On trucks, the administration hopes to finalize a regulation by July 2011 covering truck fuel standards for the 2014-18 period, according to an executive order signed by Obama.
Preliminary estimates show that large tractor trailers, which represent half of all carbon emissions from the sector, can reduce that output by up to 20 percent with existing technologies, the administration said.
Trucks mainly run on diesel fuel, while cars use refined gasoline.
Trucking companies say they support new standards as long as they are technically feasible and do not affect the performance of their vehicles.
New diesel engines emit 90 percent fewer environmental pollutants, including those that contribute to smog, than engines made 20 years ago, industry said. Trucking companies also recommend that trucks not exceed 65 miles per hour and reduce idling time to save fuel.
Trucking company executives from manufacturers such as Volvo AB and Navistar International were on hand for the Obama announcement. Auto company officials from GM, Ford Motor, and Toyota Motor also attended.