By Kevin Anderson
BBC News Website, Washington
The United States - land of the brave and home of the SUV, sport utility vehicle.
Hybrid car owners rally for energy independence in Washington
But now the gas-guzzling gargantuans are being challenged by fuel-efficient, environmentally friendly hybrids like the Toyota Prius and hybrid versions of popular models from Honda.
The hybrids could one day help to reduce the United States' output of greenhouse gasses, but despite the buzz surrounding them, they still make up a relatively small percentage of auto sales.
Hybrids use both petrol and electric motors to double their fuel efficiency and halve their emissions.
It's a well-known fact that environmentally-minded celebrities including Cameron Diaz and Leonardo DiCaprio have bought them.
As a matter of fact, Mr DiCaprio has a small fleet of four not only for himself but also for his mother, father and step-mother.
The Washington Post called Toyota's Prius hybrid "Hollywood's latest politically correct status symbol".
But it's not just environmentally minded movie stars that are snapping up hybrids by the thousands.
Hybrid cars are one of the few things that seem to bridge the political divide in the US.
So-called "Prius Patriots" including former CIA director James Woolsey drive the cars because they see it as a strategic necessity for the US to reduce its dependence on foreign oil.
According to the Natural Resources Defense Council, the US spends $200,000 every minute on foreign oil.
John Andersen, who lives outside of Washington DC, drove his Prius in a rally last summer on the 4th of July holiday, which was billed as a declaration of independence from foreign oil.
Mr Andersen describes himself as a pro-life, religious conservative who still has to be convinced of the threat of global warming, but he loves his petrol-sipping Prius.
He loves it so much he says he will never buy another traditional car.
Depending on his driving patterns, he sometimes gets as much as 53 miles to the gallon, compared to an estimated 9.6 miles per gallon for Hummer's H2 heavy-duty SUV (based on listed range and fuel capacity).
Mr Andersen has been disappointed by US hybrid efforts. "It's a darn shame the US manufacturers didn't get on the bandwagon," he said.
A hybrid version of the Ford Escape, an SUV, achieves only 33 miles to the gallon, according to the Ford website.
US automakers say they are working hard to develop hydrogen fuel-cell technology, but Mr Andersen said the widespread use of fuel cells is still years away.
"That's what great about hybrids. They are here now," he said.
Small percentage of market
However, despite the buzz about cars like Toyota's Prius, hybrids still make up a relatively small percentage of overall car sales in the US.
Toyota plans to double the production of the Prius to 100,000 a year for the US to help alleviate severe shortages in some parts of country, where buyers must wait three to six months to take delivery.
Last year, about 80,000 hybrid cars and trucks were sold out of some 17m total sales in the US, according to David Friedman, research director for the Union of Concerned Scientists' Clean Vehicle Program.
"Hybrids are becoming a mainstream product," he said, adding that if anyone would have said five years ago that hybrid sales in the US would be approaching 100,000 per year, it would have been thought "inconceivable".
Mr Friedman said that Americans would have to buy 40m to 60m hybrids over the next 10 years to stall greenhouse gas emissions at 2010 levels.
"If the government continues its vacuum of leadership, nothing will happen" to address greenhouse gas emissions, he said.
The US government sets a minimum standard for fuel economy for auto manufacturers.
But the minimum applies to a weighted average across the entire line of vehicles sold by the manufacturer, and trucks and SUVs are held to lower standards.
Furthermore, SUVs designated as heavy duty vehicles like the Hummer H2 are not held to any standard.
"If for every 40-mile-per-gallon hybrid sold, they sell a 16-mile-per-gallon gas guzzler, then there will be no effect from hybrids," Mr Friedman said.