Turbocharged trucks that are faster than a Porsche

"Quite all right," I lie. Steve slams the gearstick into first and off we go again, chasing his team-mate Max Dawson, who is now scorching around Brands like a man possessed.

These are supposed to be demonstration laps but when you put two racers on a circuit together there's really no such thing.

In the noisy, diesel-choked minutes preceding our off-track excursion, the battling wagons go at it with a ferocity that calls to mind the movie Duel. Sliding sideways in a tail-out, four-wheel drift, while another six-tonne monster tries to muscle up the inside gets the blood pumping nicely.

A runaway heavy goods vehicle takes some stopping but, when Steve's six smoking race tyres relinquish their grip, the gravel does its job. In front of 10,000 spectators at Thruxton circuit earlier this season, Steve wasn't so lucky. Max Dawson picks up the story: "I saw all these yellow flags, I could see two truck lines and so I followed them on to the grass and I could see a red cab in the trees. And on his roof was ERF. Steve must have gone a quarter of a mile across a field, through the banking and up into these trees. If you're doing 100mph and you hit grass you just gain speed, you can't stop."

Born in the Eighties, truck racing is a phenomenon on the continent. Some 200,000 fans descend on Germany's Nurburgring each July for the biggest event of the year

The first British race, at Donington in 1984, was won by a visiting Italian trucker who cleaned up on the track, then reattached his trailer, made his delivery and headed home.

Racing trucks have come on since then. With 12-litre turbocharged diesel engines producing around 1,000bhp, race trucks are twice as powerful as their road-going counterparts. From a rolling start, some will reach 100mph faster than an entry-level Porsche 911.

Built around a production truck chassis reinforced with a heavy roll cage, from the outside a racing truck looks very much like a standard HGV. It's similar to drive, too.

"It's the same dash as a standard truck and all the pedals are the same," says Max. "You've just got rid of the fancy leather seats."

But most are modified to varying degrees. Water-cooled brakes, race shocks and sticky-slick tyres help keep all that monstrous momentum in check. And moving the engine block backwards, to redistribute weight and improve grip, is a popular trick.

"It's like a big go-kart really, because the engine's in the middle," says Max. A go-kart with the driver's seat suspended more than a metre from the ground...

Less extensively modified than Steve Horne's sophisticated ERF Class A truck, Max's is a Class B. "My engine's got high-lift cam, injectors, turbo. Then you've what they call a 'Ted Rogers' diff, a 3-2-1, which gives you 100mph at 2,000 revs," says the former British Class B champion.

"To build one like mine from scratch you're talking maybe £20,000. But money's coming into the sport now and people are racing £100,000 trucks against £10,000 trucks. And you can't compete on a small budget."

Truck racing is cheaper than most forms of car racing. Teams tend to be connected with the haulage trade and, with modest sponsorship, can race for less than £1,500 a season. "It's not a poor man's sport but you don't need to be mega-rich," explains Max, an HGV fitter from Skipton.

A typical truck race lasts around 20 minutes or eight to 12 laps depending on the circuit. Up to 23 trucks from both classes race together and although it's not meant to be a contact motorsport, "it gets a bit hairy out there".

"They'll be two or three abreast," says Max, "and your wheels are usually rubbing their side panels as you're going through. One little nudge sounds so loud you think you've ripped your wagon in half. But when you get out it's only a scuff."

Race regulations limit top speeds to 100mph. "The windscreens are so big they'll blow in," explains Max. And barriers are more likely to withstand a 100mph impact than a 130mph one.

Next time Steve and Max drive at Brands Hatch will be at the championship finals. It's 11 years since trucks raced at Brands and it promises to be a spectacle.

The Truck Superprix, with the final rounds of the 2005 British Truck Racing Championship, is at Brands Hatch, Kent, on 5 and 6 November