It is known as the Inland Empire: a vast stretch of land tucked in the high desert valleys east of Los Angeles. Once home to fruit trees and Indians, it is now a concrete sprawl of jammed freeways, endless suburbs and shopping malls.

But here, in the heartland of the four-wheel drive, a revolution is under way. What was once unthinkable is becoming a shocking reality: America's all-consuming love affair with the car is fading.

Surging petrol prices have worked where environmental arguments have failed. Many Americans have long been told to cut back on car use. Now, facing $4-a-gallon fuel, they have no choice.

Take Adam Garcia, a security guard who works near the railway station in Riverside. Like many Inland Empire residents, he commutes a huge distance: 100 miles a day. He used to think nothing of it. But now, faced with petrol costs that have tripled, he is taking action. He has even altered the engine of his car to boost its mileage. 'I have to. Everyone does. I can't afford to drive as much as I did,' he said.

Recent figures showed the steepest monthly drop in miles driven by Americans since 1942. At the same time car sales are collapsing, led by huge SUVs.

General Motors, once the very image of American industrial might, is in deep trouble. Cities are now investing in mass transit, hoping to tempt people back into town centres from far-flung commuter belts where they are now stranded by high petrol prices.

Jonathan Baty used to be a pioneer. The lighting designer has cycled to work every day since 1993. It's a nine-mile round trip through the heartland of a car-based culture once famously termed 'Autopia'. But now Baty has company on his daily rides as others choose two wheels rather than four to navigate southern California's streets. 'We have seen a whole emergence of a bike culture in this area. There is a crescendo of interest,' said Baty, who does volunteer work for a cycling group, Bicycle Commuter Coalition of the Inland Empire.

In Riverside, bus travel is up 12 per cent on a year ago, rising to 40 per cent on commuter routes. Use of the town's railway link is up eight per cent. A local car pooling system is up 40 per cent. It is the same in the rest of the US. In South Florida a light rail system has reported a 28 per cent jump in passengers. In Philadelphia one has shown an 11 per cent rise. Even nationwide scooter sales have shot up. At the same time car sales are hitting 15-year record lows. Last week major American car-makers reported a devastating 18 per cent drop in car sales.

The numbers point to a more fundamental shift. In America car sales carry a symbolic value that transcends the wheeler-dealering of the showroom. This is a nation of fabled road trips and Route 66. 'There is an American dream of mobility and freedom and wealth. The car is part of all that,' said Professor Michael Dear, an urban studies expert at the University of Southern California.

In the 1950s the confident nation that helped win the Second World War was expressed in classic car designs of huge fins and open tops. By the 1990s it had become the Hummer, a huge bulking car born from the military. Now there is to be another shift. For, hidden within the car sales figures, is a more complex story than a simple fall. Sales of big cars are plummeting while smaller vehicles, especially fuel-efficient hybrids, are replacing them.

GM has now closed SUV production at four plants. Its Hummer brand is up for sale, or might even be closed. GM is ploughing huge resources into its 2010 launch of the Chevy Volt, a hybrid car that may get up to 150 miles a gallon. It needs to. GM's share price recently hit a 54-year low, prompting one top investment bank to warn that the firm could go bankrupt.

The Volt, and cars like it, could become symbols of a new more conservation-minded car age. As Americans enjoyed the 4 July holiday weekend, increasing numbers of them were staying at home rather than hitting the road. Newspapers were full of tips for 'stay-cations', not weekend breaks away. Customs once scorned, such as car pooling and cutting out trips to the mall, are now commonplace. The fact is, the vast majority of Americans cannot give up their cars altogether. Too many cities lack any reliable public transport.

Adam Garcia is one of those caught. He does two jobs and his daily road trip by car is a necessity. 'We don't have much of a choice. I have to drive,' he said. Sacrifices come elsewhere, in giving up trips to the cinema and to see friends.

But America's changing relationship with the car is just part of the story of how the most powerful nation is changing in the face of the oil price rise. America has been built on an oil-based economy, from its office workers in the suburbs to its farmers in the fields.

Since the 1950s and the building of the pioneering car-orientated suburb of Levittown in Long Island, the American city has been designed for the convenience of the car as much as its human inhabitants. People live miles away from jobs, shops or entertainment. If you take away cars, the entire suburban way of life collapses. To some, that development is long overdue.

'Suburbia has been unsustainable since its creation,' said Chris Fauchere, a Denver-based film-maker who is producing a new documentary on the issue called The Great Squeeze. 'It was created around cheap oil. People thought it would flow easily from the earth forever.'

Fauchere's film, due out later this year, aims to tackle the profound changes caused by a world where oil is becoming scarcer. He does not think that it is going to be easy for America to make the adjustment. 'It is going to be tough. It is like a chain reaction through the economy. But if you look at history, it is only crisis that starts change,' he said.

The suburbs are already being hit. As cars become more expensive, the justification for suburbs seems to disappear. Some commentators have even suggested that suburbs - once the archetype of an ideal American life - will become the new slums.

In the face of expensive fuel and crashing property prices, the one-time embodiment of a certain American dream will become crime-ridden, dotted by empty lots and home to the poor and unemployed. That is already happening as crime and gang violence has risen in many suburban areas and tens of thousands of homes have been reposessed because of the mortgage crisis.

In effect, suburbs will become the new inner cities, even as once-abandoned American downtowns are undergoing a remarkable renaissance. Even malls, the ultimate symbol of American life since the war, are undergoing a crisis as consumers start to stay away.

But there are even deeper changes going on. The car, the freeway system and cheap air travel made America smaller. Everywhere was easily accessible. That, too, is ending. Higher fuel prices have dealt a terrible blow to America's airlines. They are slashing flights, raising costs and abandoning routes. Some small cities are now losing their air connections.

In effect, America is becoming larger again. That will lead to a more localised economy. To many environmentalists that is a blessing, not a curse. They point out that cheap fuel for industrial transport has meant the average packaged salad has travelled 1,500 miles before it gets to a supermarket shelf.

'Distance is now an enemy,' said Professor Bill McKibben, author of the 1989 climate-change classic The End of Nature. 'There's no question that the days of thoughtless driving are done.'

The worst hit parts of the US are not yet the suburbs or the freeways of southern California, but the small towns that dot the Great Plains, Appalachia and the rural Deep South. Even more than the Inland Empire, people in these isolated and poor areas are reliant on cheap petrol and much less able to afford the new prices at the pump. Stories abound of agricultural workers unable to afford to get to the fields and of rural businesses going bust.

Even farmers are not immune. They might not need a car to get to their fields but their fertilisers use oil-based products whose prices have gone through the roof. A handful have started using horses again for some tasks, saving petrol on farm vehicles.

The American dream of the last half century is thus changing. The car and its culture is now under a pressure unimaginable even a few years ago. 'The frontier of endless mobility that we've known our entire lives is closing,' said McKibben.

America's excess has had many imitators. Recently a delegation of Chinese government officials and architects visited an Arizona suburb near Phoenix. Approving notes were taken as they surveyed the luxurious car-driven suburban lifestyle on display. This was just one of the many delegations that regularly come from the Far East or South America.

Even as America is sobering up from its excess of cheap oil, other parts of the world are seeking to join the party. They, too, want homes far from dirty city centres, huge open roads and fast cars. It is still a beguiling vision of freedom, mobility and bountiful riches.

McKibben spent last week on a visit to Beijing. He was worried about what he saw. Even as America's obsession with the car lifestyle is ending, others are embracing it. 'The Chinese have spent the Bush years starting to build their own version of America. A key question for the planet is whether they still have time to build a version of Europe instead - global warming will probably hinge on the answer to that question,' he said.



Car culture

The Grapes of Wrath

John Steinbeck's classic novel follows 14 passengers and a dog as they set out from the Oklahoma dust bowl for California in a decrepit sedan. 'The ancient Hudson, with bent and scarred radiator screen ... with hub caps gone and caps of red dust in their places - this was the new hearth, the living centre of the family; half passenger car and half truck, high-sided and clumsy.'

On The Road

Written in April 1951, Jack Kerouac's autobiographical account of a road trip across the US and Mexico with Neal Cassady is the definitive account of American wanderlust.

Rebel Without a Cause

James Dean's fate is sealed when he accepts the challenge to a Chickie Race from the high-school gang of Buzz Gunderson. The game ends in tragedy for Buzz, when his car goes over the cliff. Dean was later to die when he crashed his Porsche Spyder.

Bullitt

The 1967 Dodge Charger was the most elegant car of Detroit's muscle era. The car, with its sinister occupants, is destroyed by Steve McQueen, left, in a Ford Mustang GT Fastback, and consumed in a ball of flame. The scene provides the climax to nine minutes and 42 seconds of cinematic car intensity in the hills of San Francisco.