Roger Bell lines up the off-roaders
"Burn some rubber this weekend. See a different world." The ad's catchline, set against a volcanic backdrop, is for Vauxhall's Frontera. In the land of make-believe that off-roaders inhabit, it might have been for a Discovery, Jeep, Sportrak, Maverick, Shogun or Land Cruiser - names evocative of derring-do in the great outdoors.

Vauxhall stokes the myth. "Volcanic ash is a treacherous surface. Beware." Useful information on the Tesco run. "In extreme cases, it can block escape routes entirely." So can rush-hour traffic in the urban jungle where most eruption-defying 4x4s do their stuff - with four-wheel drive disengaged if possible.

Logic has little to do with the runaway success of go-anywhere 4x4s in Britain. Around 13,000 were bought here in 1986. Last year's tally was around 80,000. Although the boom seems to have peaked, 4x4s look set to retain an impressive 4 per cent of the new-car market, thanks largely to people who buy them for emotional reasons, not practical ones. Just as well. Every bridleway in the land would be an axle-deep quagmire if a tenth of the nation's estimated half-million mud-pluggers regularly took to the hills. Fortunately, they do not.

To run a car designed to dump sheep fodder at altitude is palpably daft if your only forays off-road are through the garden gate. Or is it? Suburbanites who justify their 4x4s on safety grounds do have a point. Most off-roaders are heavier than cars of comparable length - and mass is a protective ally. Good visibility is another safety bonus. Because of their big wheels and lofty suspension, you sit tall, all the better to see. Over-the-roof (and hedge) visibility can give the 4x4 driver advance warning of hazards ahead. It's also good for sightseeing - an appropriate attribute for a leisure-orientated "lifestyle" vehicle.

Four-wheel drive is not on its own the attraction of off-roaders. If it were, sales of all-drive cars would have boomed, too. They haven't, with good reason. This side of Braemar, the benefits - mainly mobility, though Audi points to skid-free cornering, too - hardly justify the hefty price premium, especially as extra weight and friction penalise performance and economy. Besides, there's nothing to distinguish a 4x4 car from a 2x4 one, other than its badge.

The macho off-roader's attraction is that it looks the part of an irresistible force - square-jawed, impregnable, unstoppable. Image is everything. Brawny Chrysler Jeeps and LR Discoverys have it, the original Ford Maverick/Nissan Terrano twins did not. Sales - more than six to one in favour of the Discovery - underline the point.

The trouble with 4x4s of an agricultural bent is that they're so heavily compromised. It shows in cumbersome handling, sway on corners, imprecise steering. Stiff springs mean a bumpy ride, extra weight and wind resistance, less zeal and economy. Off-roaders can be terrific fun on tricky terrain. You need a streak of masochism, though, to enjoy the wallet-bashing thirst and jitterbug ride of the majority on motorway marathons.

So have 4x4s been rumbled? Is the brake on sales down to their truck- like behaviour as road cars? Not really. It has more to do with market forces, not least with the rise and rise of alternative "lifestyle" cars, notably monospace MPVS. Between them, the Ford Galaxy/VW Sharan twins are now outselling the Discovery, Britain's best-selling 4x4 in the early Nineties.

As the opposition has intensified and diversified, so the Discovery's market share has slipped, from more than a third to less than a quarter. Toyota's new Landcruiser Colorado and Ford's American-made Explorer are the latest challengers to chip away at its lead. Others on the way include Mercedes-Benz's AAV (also from the US), Honda's interesting CR-V, due here in June, and a new Frontera from Vauxhall. The existing model is still suffering from the mauling it got in Top Gear's JD Power customer satisfaction survey.

Significantly, the rising star is not a traditional off-roader but Toyota's mould-breaking RAV4, which has come from nowhere to eclipse the Frontera's second place. The RAV4, modest on the rough stuff but hot on Tarmac, is seen as the precursor of 4x4 funsters to come. Land Rover will launch its own SUV - sports utility vehicle - next year, probably under the Highlander name. Others, biased more towards everyday motoring (such as the 2.0- litre Honda CR-V), will precede it. There's a lot more mudslinging to come in a 4x4 sector that's undergoing dramatic change.

Who's who in the off-road jungle

Asia Motors Rocsta, from pounds 9,500 Rock yes, star no. Korea's naff crib of a Jeep is as diminutive as it's dire on Tarmac. Excels as tardy wheels for small gamekeepers.

Daihatsu Sportrak, from pounds 10,635 Cramped, boxy Daihatsu is long in the tooth, of limited ability. Saving grace is price and economy. Slow, coarse and underwhelming on the road. New models soon.

Ford Maverick, from pounds 17,650 Narrow, perpendicular styling blamed for poor sales, not ineptitude. Should do better after recent steroidal workout. Best is 2.7 turbo-diesel. Cloned with Nissan Terraro.

Jeep Cherokee, from pounds 15,550 Wild West to West End. Cherokee looks the part, undercuts Discovery and handles more like a car than a blancmange. New Grand Cherokee is pricy but good.

Lada Niva, from pounds 7,995 From Russia without love. Feels and drives the way it is - old, cheap and crude. Rough-and-ready, utilitarian with little to commend it other than simplicity and price.

LR Discovery, from pounds 19,765 Britain's best-selling off-roader by a long way. For: comfortable, roomy, goes anywhere. Against: slow, clumsy square- rigger.

LR Range Rover 4.6 HSE, pounds 47,765 The mother of all 4x4s, and the least compromised. Desirable prestige tank with fine manners. Huge and thirsty V8 engine, modest Ford Mondeo 1.8 performance.

Mercedes-Benz G-wagen, from pounds 39,000 Proof that the Germans can get it wrong. Forget the frumpy G-wagen. Wait for Merc's trendy US-made AAV - all activity vehicle. Watch out, Discovery.

Mitsubishi Shogun, from pounds 19,965 Cheaper models are still popular as Discovery alternatives; more expensive ones fail to outrank the new Range Rover. Three and five doors, nice V6 engines, civilised.

Ssanyong Musso, from pounds 16,000 Name, styling, tardy performance undermine street cred of Korean diesel. Roomy and well made, new petrol model quicker.

Suzuki Vitara, from pounds 10,920 Fourth in 1996 sales, behind Discovery, RAV4 and Frontera. Style and price are main attractions of pocket scrambler. Doesn't fall over, like previous mini Suzuki.

Toyota RAV4, from pounds 14,269 A GTi once removed. Less the boxy mud-plugger, more the stylish 4x4 fun car, with no more off-road ability than most people need. Corners well.