More efficient vehicle technologies -- like lighter, more aerodynamic designs -- could be combined with alternative power sources to reduce petroleum use.
Greener cars that use alternative fuels could help the United States slash its greenhouse gas emissions from everyday driving a full 80 percent by 2050, according to a scientific study out Monday.
That could lead to a more than 13 percent cut in overall US pollution into the atmosphere, with consumer-driven cars and small trucks currently responsible for 17 percent of the nation's greenhouse gas emissions, said the study.
However, sticker shock could turn off many consumers, with alternative fuel vehicles costing several thousand dollars more than today's prices.
Still, the long-term benefits would outweigh the early costs, said the report by the National Academy of Sciences, which called for subsidies and tax incentives to ease the burden on consumers who want to drive green.
"These are things that will not happen in the market naturally," committee chair Doug Chapin told reporters. "There has to be real teeth in these policies."
The study envisions cars and small trucks of the future that drive a stunning 100 miles per gallon (42.5 kilometers per liter), way over the 25 miles per gallon that they did on average in 2005.
More efficient vehicle technologies -- like lighter, more aerodynamic designs -- could be combined with alternative power sources such as biofuel, electricity or hydrogen, reducing petroleum use in 2050 by 80 percent as well, it said.
"There is no silver bullet that is adequate by itself," said Chapin.
Fuels under consideration include corn-grain ethanol and biodiesel, which are already being produced in commercial quantities. Natural gas was ruled out because its greenhouse gas emissions were too high.
The study also pointed to "much greater potential" in fuel from wood waste, wheat straw and switchgrass, known as biofuel from lignocellulosic biomass.
"This 'drop-in' fuel is designed to be a direct replacement for gasoline and could lead to large reductions in both petroleum use and greenhouse gas emissions," it said.
The study examined hybrid electric, plug-in electric and battery electric vehicles already on the market including the Toyota Prius and Chevrolet Volt, as well as hydrogen fuel cell electric vehicles like the Mercedes F-Cell, scheduled for market release in 2014.
High up-front vehicle prices would be expected to endure for at least a decade, even though it would cost less to fuel up and drive greener cars, it said.
The study said the benefit to society in terms of energy cost savings, better vehicles, reduced petroleum use and lower greenhouse gas emissions would be "many times larger than the projected costs."
The goals set out by the study, which took two years to produce, will be "difficult but not impossible to meet," Chapin said, as long as they are guided by strong national policies.
He acknowledged that projecting until 2050 created significant uncertainty in the study, but urged many policies and approaches to be pursued at the same time.
"If the goals are not completely met, the effort itself and partial success is expected to yield valuable benefit," Chapin said.
According to committee member David Greene of the Howard H. Baker Center for Public Policy, incentives such as subsidies or mandates would be needed to "overcome the initial cost barriers for the advanced technologies."
"In the long run, we remove all of those special subsidies or mandates and let the market decide which vehicles it prefers," he said.
The study was sponsored by the US Department of Energy's Office of Efficiency and Renewable Energy.
President Barack Obama last week sought to preserve green energy research after an impasse with Congress sparked an 85 billion dollar austerity drive and widespread budgets cuts.
Obama, who has also urged Congress to do more to fight climate change, plans to introduce further efficiency standards for cars and make a fresh push for cleaner energy, but those policies face an uphill battle among Republican lawmakers who say the costs are too high.