In high summer, deep in the Swedish countryside, you could easily believe Rebel Without a Cause or The Wild One are being remade. The quiffs, classic cars and 1950s clothes aren't for show, however. These people aren't costumed extras, they are raggare, members of the largest pop-culture tribe in Sweden, and one of the most influential in Scandinavia.

Rock'n'roll never died for the raggare: they are still devoted to the music, the fashion, the aesthetics. For 50 years they have kept its spirit alive, but where rock'n'rollers in other countries have dwindled into small groups, in Sweden they have gone from strength to strength – there are now estimated to be half a million of them.

The first raggare would travel in convoy from one hick town to the next to beat lumps out of each other and ogle the women. There are still organised raggare brawls, but the movement is part of the mainstream now, its most visible manifestation the cheap 50s and 60s US cars the raggare still drive and the vintage clothes they wear. You can have three generations of raggare within the same family, and there was no more eloquent statement of raggare respectability than the 12 kronor commemorative raggare stamp issued by the Swedish post office a few years back.

Arboga is a town of 10,000 people, 80 miles or so west of Stockholm. It's a dullish place, with late-night entertainment limited to a few service stations dishing out food. There's nothing to do here, which means it's a perfect place for raggare culture to thrive. The Burning Wheels are the smallest of three chapters of raggare from Arboga. They meet every Sunday at Georg's Garage to rev their engines, play rock'n'roll records and talk about the 1950s, while their children run around getting ice cream handprints all over the car seats.

It wasn't always like this, according to Georg. "We used to meet up on Sundays to have fights. We were honest fighters. No weapons, no martial arts, no kicking – and if you fell on the ground it was all over and you'd buy the guy a drink."

The raggare didn't confine the fighting to themselves. They singled out punks and hippies for beatings, and did it so often that the Rude Kids, a Swedish punk band, released a single called Raggare Is a Bunch of Motherfuckers. "Those were the drinking days," Georg says. "The crazy drinking days." If you drink too much nowadays, you'll be kicked out of the Burning Wheels, they say.

The raggare have always tended to be drawn from country folk: farmers, petrol station owners, low-skilled workers. The growth in their numbers is the result of the differing fortunes of the US and Swedish economies over the decades: successive oil crises and a poor exchange rate saw Americans trading in gas-guzzlers for more economical models; the Swedes, relatively rich in comparison, bought their cars for a song.

For young Swedes, these giant American cars, which contrasted with the safe, boxy Volvos their parents drove, were the ultimate symbols of rebellion. And they were dirt-cheap. "They were stupid," Georg says about the Americans. "Some of the cars were limited edition. They built maybe 70 of them and they were selling them to us for a few thousand when they were collector pieces."

Georg picked up his first US muscle car, a black 1965 Pontiac, for $2,000 in Los Angeles in 1980. He found it in a lot, rusted and part-inhabited by a eucalyptus tree. By the time he'd shipped it home, sourced original parts, resprayed and kitted out the whole body, it was worth 20 times as much, with an engine that purred and a stereo that roared. The latter is the only concession to modernity acceptable in a raggare's restored car; music is a huge part of the culture. "You don't exactly want to have hip-hop playing from your car when you're cruising," says Martin, a farmer who drives a lime green Chevy. He listens mostly to Creedence Clearwater Revival. "That music came from a period when America was really great. You can hear it in the lyrics."

Martin's top-of-the-range sound system is hidden inside the glove compartment. Every weekend, in car parks and petrol station forecourts up and down Sweden, the rest of Scandinavia, and even in some parts of western Russia, raggare gangs play out their classic rock'n'roll albums until their car batteries pack in.

When the raggare have parties, they tend to have them in their garages: comfortable enough spaces, filled with pots of grease, car jacks and stacks of fenders. The more capable raggare jitterbug and twist; others shuffle from foot to foot, stopping occasionally to pull out the kink in a poodle skirt or run a comb through a greasy quiff.

Maud is the longest-standing female member of the Burning Wheels. She's short of cash at the moment, and has to cruise around in a 20-year-old Volvo – and Volvos are to raggare what dirty overalls are to mods. "I fell in love with the scene thanks to my grandparents," she says. "The music they listened to and the cars they drove are so attractive." Maud is also involved with a girls-only raggare group who visit schools as part of a raggare awareness group, teaching pupils about the raggare lifestyle and the notion of respect.

When the first raggare appeared, they caused moral panic across Sweden, where they were seen as an oversexed bunch of hard partiers. As the original raggare have grown older, they've been trying to heal their reputation. "It's important to be a gentleman," says Georg. "If you want to join the Burning Wheels, you have a one-year probation period. It's not easy to join. You have kids driving round in their parents' Volvos calling themselves raggare when they're not."

That free use of the word has caused problems. Raggare get blamed when far-right gangs attack Gypsy camps and smuggle drugs. To outsiders, gangs in cars out drinking are all raggare. Not to the Burning Wheels. "We're like craftsmen. The lifestyle is an art," says Martin. "It's not just drinking and driving fast. There's responsibility with what we do."

It's funny how often the words respect and responsibility are used by a group who take their cues from music and films whose very purpose was to express rebellion. That's partly the result of the Swedish government realising there was more to be gained from embracing the raggare than alienating them. In the 60s, the government made the decision to consult the raggare about decisions that might affect them – so now they pay no car or import tax on their vehicles, and Sweden has the largest collection of classic cars outside the US. Another 6,000 were imported last year alone.

When winter comes around, the majority of raggare go into hibernation. They tuck their Buicks under blankets, slip off their blue suede shoes and pull on their snowboots. And the next time they pull out of their driveway with Chuck Berry on the stereo, it'll probably be in a nice warm Volvo.