A landmark energy bill requiring greater fuel efficiency in US cars and trucks for the first time in 30 years has been passed by the Senate.
General Motors is one US carmaker to show off its green credentials
The bill was approved after Democrats dropped efforts to impose $13bn (£6.38bn) in taxes on big oil firms.
It will now be passed to the House of Representatives, and if approved will be sent to President George W. Bush, who is expected to sign it.
If passed, vehicles would consume up to 40% less fuel per mile by 2020.
This would save 1.1 million barrels of oil per day, equivalent to half the oil imports from the Gulf, according to Democrat Senator Daniel Inouye, chairman of the Senate Commerce Committee, which introduced the bill.
He also pointed out that the measure would save consumers $22bn at the pump and reduce annual greenhouse gas emissions by 200 million tons.
Senate Majority Leader Harry Reid of Nevada added that the bill was a "step to fight global warming".
The White House had been strongly opposed to a tax package in the original bill that would have seen oil companies paying higher taxes to allow the government to provide tax breaks for renewable electricity firms.
But with these measures abandoned, it is now expected that President Bush will allow the bill to be passed into law.
The energy legislation requires car firms to achieve 35 miles per gallon (15 km per litre) in fuel efficiency, up from 27.5 miles a gallon for passenger cars and 22.2 miles a gallon for minivans, SUVs and other light trucks.
A massive boost in the use of greener fuel sources, including ethanol, as motor fuel, to 36 billion gallons a year by 2022 would also be on the agenda.
This is more than a five-fold increase from the 6.5 billion gallons of ethanol expected to be produced as car fuel this year.
But the Democrats still came under fire from some environmentalist groups for not standing firm on the controversial tax measures.
"The Senate Democrats should show some backbone," said
Brent Blackwelder, president of Friends of the Earth.