Poseurs who cruise the cities in 4x4s are missing a vital accessory ­ spray-on mud

This is the weekend on which the Army has announced that the age of the heavy battle tank is over.

They're everywhere. And they're not only on the move, they're where they were never meant to be: on the roads. They can't go anywhere else at the moment; venture off the black top and that would be that: masked men from Maff, captive-bolt stun gun through the radiator, and on to the blazing pyre.

If only. But it won't happen. Despite their high-traction tyres, the winches, the inclinometers and GPS systems and all the other paraphernalia of post-industrial symbolic masculinity, most 4WD owners are merely making a style statement: just a pack of etiolated city folk, buying into yet another brand. Off-road is for the ads. In reality, darling, one has to think about one's Pradas.

And just look at the ads. "Not just a kerb-climber," trumpets one. (And if not, what? A kerb-crawler? A crusher-flat of other, lesser breeds occupying road space?) In another, controversial and hastily withdrawn ad, showing all the sensitivity we have come to expect from South Africa, what they doubtless think of as a "native woman" stands in the slipstream of a Land Rover, her pendulous breasts blown diagonal by the rush of air. Freedom, power, oppression: what more could a 4WD driver yearn for. And how about the new Lexus 4WD. "Leave the road behind, not the luxury," whines the tagline, over a picture showing what appears to be a recently sacked executive up a barren mountainside, surrounded by the stock of Alessi accessories on which he has clearly spent his redundo.

The fool. He's in the wrong business. The answer is mud.

Would we lie? Mud. There are farmers everywhere, willing to do business. Guaranteed, sterilised, foot-and-mouth-and-everything-else-free mud. Appelation controlée mud: Cotswold mud, Highland mud, black foetid Lincolnshire potato mud. Spray-on mud. In a can. No need to get your hands dirty.

And never mind the mountainside. Try Fulham, South Kensington, Chiswick, the naffer parts of Cheshire, the posher 'burbs of anywhere, any morning in term time. There they are, the mothers, coiffed to the rooftop, disgorging tiny Joes and Clytemnestras into their £2,000-a-term forcing-houses... and disgorging them from what? Four-wheel drives. Big, up-yours, Geoffrey-has-the-Merc-and-this-is-our-runabout four-wheel-drives. Range Rovers and Discoveries, Land Cruisers and Suzukis, Shoguns and Foresters, and every one of them clean as a whistle.

Now's the time for mud. Or else the environmentalists will get you. They're already on the march. In America they're demanding massive tax hikes for 4WD guzzlers; in Britain, a sliding tax scale was supposed to be in place this year but was "held over". But it's only a matter of time. "It's a sad reflection of people who think it is impressive to drive around in over-sized armoured personnel carriers when it does great harm to the environment," says Tim Brown of the National Society for Clean Air. "There are two types of people who buy them: those who are ignorant, and those who don't care." And there's the real reason we should all righteously despise 4WDs and campaign for their removal from every road, for ever: the people who drive them are awful.

Did Latil of France see this coming 103 years ago when they started making 4 x 4 drive units? Did Felix and Normal Caldwell, holed up in their South Australia fastness, have an inkling of the school-run bandettes, the Essex-boys-done-good, the soft, porky Wirral status hounds when they went into business building Caldwell Vale 4x4 trucks in 1907? Was the (Australian, again) Big Lizzie road train of 1915 heralded as the Thin End of the Flaming Wedge? But it was. Technology designed for rough terrain and harsh conditions has now become as stylised a statement of urban aspiration as the military-inspired "cargo pant", the ludicrously tough commando shoe, as the whole Urban Warrior schtick which seeks to neutralise the ludicrous comfort and safety of our every-day lives with pointless capacity to face danger which will never, ever happen.

There are, of course, righteous 4WDs. Tom Barnard, motoring editor of Auto Express, contrasts the "proper working vehicles such as the Land Rover Defender, used by farmers who fling sheep in the back" with "fashion accessories... it's like wearing a pair of Timberland boots". For the Righteous Ones, it's all about the vehicle. Cranking up the dirt trails of central Australia in 125F heat, the Toyota Land Cruiser ­ preferably air-conditioned ­ is a sensible choice. Men who do Men's Stuff, whether as safety inspectors, pipeline engineers, builders or farmers, are making no statement with their Land Rover other than "this is a tool of my trade". But for the rest, it's simply risible.

And the risibility falls into two categories: the Deceivers, and the Self-Deceivers.

Joe and Clytemnestra's Mummy is, of course, the Deceiver par excellence. Her deception can fall into two sub-sets. The first is the Deception of Property. Like the horrid Barbour jacket, the 4WD is designed to give, in an urban setting, the impression that its owner has another life, deep in the countryside. It's a curiously British phenomenon; while the rest of Europe longs to appear at home in the city, here it's essential to appear as though one is only in London by accident, and at any moment will return to the Godly shires, there to sink into a frightfully English rural lunacy. And if you don't actually possess the "little place" in Gloucestershire, the 4WD will give ­ at least to the peer-group idiots you're trying to impress ­ the impression that you do.

The other sub-deception in this class is the Deception of Insouciance. Confined to those who actually do have houses in the country, it aims to give the impression that they have inadvertently forgotten they are in a city now, and are ingenuously continuing in their doghair-and-horse-shit rural ways. But it is a pose entirely calculated. Its practitioners can spot the difference between a Shogun LWB and a bottom-of-the-range Land Rover at 500 yards, and the difference is £16,515; because what it's really about is not successfully carrying off the deception, but demonstrating that you can afford to attempt the deception.

The second super-class of deception is the Self-Deception of Intrepidity. This is almost invariably practised by men; equally invariably by men who construct their masculinity on the old, militaristic, pre-post-industrial model, where a Real Man shot snakes, ate sand, fended off volcanoes and nasty wogs, and, in general, wrestled with his environment. The irony is that, in our post-industrial, post-anything-actually-working-properly age, the meekest City data clerk spends more time (courtesy of Railtrack, London Underground, local government, the NHS, the licensing laws and the Inland Revenue) wrestling with his environment than our ancestors ever did.

But that doesn't concern the group of Self-Deceivers. Witness, for example, Peter Bradley, writing in an online 4WD magazine (4wd.sofcom.com): "The weekend saw a small selection of northern 'eventers' descend upon the otherwise relatively peaceful town of Duns... the modified Ninety had a hell of a job climbing the bank ... Neil brought his impressive two-piece bridging ladders out... this was pioneering stuff ... Maddi reached the top and disconnected, peeling off to the right ready for a very slippery descent... standing over the winch I watched in horror as the drum screamed, like we had just hooked up a Black Marlin, the cable paying out at the alarming rate of 4 or 5 feet a second..." And so on. Perhaps a touch less icky than the Deceivers. But all the same, there are around 100,000 4WDs being sold in Britain every year. And not to people who need them, either.

Hence the mud. Crank up the deception. Someone should get on to it before the Japanese do. A Land Rover Deceiver 2.8 in warrior grey, with optional loam: actually, it sounds quite appealing. Zip up the camouflage flak jacket! Strap Joe and Clytemnestra in the back, and to hell with the air quality. The Fourdies are coming!