Some industry observers thought BMW had lost its marbles when it decided (a) to build a factory in South Carolina and (b) to get involved with off-roaders in an area of the market it had never tackled before. Well, both projects have turned out to be notable successes.BMW Spartanburg is a major element in livening up the South Carolina economy, with a quality audit much tougher than many established US car plants operate. And the X5 is a top seller in its particular niche of the market.And what niche would that be? Essentially, it's the one which accommodates luxury 4x4s intended for buyers who don't have the remotest interest in driving off the edge of mountains.I've always wondered about the value of those super-tough off-road exercises involving vehicles priced at £30,000 and more. Great fun, agreed. But how many real-life owners in their right mind will ever take even a year-old 4x4 of that kind into potentially car-wrecking - even somersault-possible - terrain?The companies which build executive or luxury class 4x4s have identified a potential ownership among people with a fair amount of spare cash, who like the idea of a strongly built high-set vehicle, mechanically and from an equipment point of view a lot more refined than, say, a Defender, able to double as a town car and as leisure transport, whose toughest off-road task may be to go to a beach or a riverside, or across a gravelled golf course car park.Off-road purists may curl a lip at this kind of thing, but it has given us some excellent cars, and the X5 is one of the leaders in the sector. It also has plenty of off-road capability in reserve.Launched as the 4.4i, the X5 has very robust unitary construction, a wide track, a long wheelbase and lightweight suspension similar to the system used on the 7-series saloon. One of its great selling points in North America is that it recorded the best score ever seen in the equivalent of the Euro NCAP crash tests, and that's not a bad recommendation here, either.Now the X5 is easing down into a lower price category with the arrival of the 3.0i and the 3.0i Sport. But the smaller engine doesn't mean that power is slumping in the power to weight ratio calculations. This is the excellent and recently up-rated straight-six as seen in the 3-series and 5-series ranges, and in the Z3 roadster. Upwards of 230bhp means that there's still plenty of performance available.And, unlike some other bulky 4x4s, the X5 can use it. The great thing about this car is that it's not an off-roader tamed for road use, rather a fine road car with an off-tarmac capability. It sweeps imperiously along motorways, but it also has fine poise on fast country roads, partly because the centre of gravity is some way below roof level, and it soaks up lumpy tarmac. BMW has also fitted a much more responsive rack and pinion steering system than is available in some of the X5's rivals.The interior is roomy, and far more sophisticated than you find in some 4x4s at much higher prices. Driver and passengers have the elevated view of the road, and of other people's properties, which is one of the charms of 4x4 motoring.A five-speed manual transmission is standard, but there's the extra-cost option of a five-speed Steptronic which offers such lovely, slurred changes as a full automatic that I wouldn't bother much about the sequential mode.The horizontally split tailgate may obstruct the view through the rear-view mirror, at least as far as showing up the lights of a car immediately behind is concerned, but it's a practical design with a proper load-bearing lower half. A pull-out floor, as on the BMW Touring, is another option.For off-roading, the X5 has a high ground clearance, an aluminium sump guard, dynamic stability control, an automatic, electronically operated differential brake and so on, but no transfer box. BMW skipped that and fitted hill descent control, as pioneered by its one-time subsidiary Land Rover.There's a Sport specification at a premium of £1900. It includes 19" alloy wheels, revised suspension settings, a multi-function steering wheel, electrically operated sports seats with memory, and various trim enhancements. But the standard car is stylish, well-equipped and well turned out, and it's better value than several bloated-price rivals. Engine 2979cc, 6cylinders Power 231bhp @5900rpm Torque ib/ft @3500rpm Transmission 5 speed manual Fuel/CO2 22.2mpg / 305g/km Acceleration 0-62mph: 8.5sec Top speed 128mph Price From £33301.00 approx Release date 01/01/2001