To help realise its potential for speed, the X5 has the 4.4-litre, variably- valve-timed V8 already seen in grander BMW Fives and Sevens. It also has four-wheel drive, and is made in South Carolina alongside the Z3 sports car. Sounds good and sporty so far, then. However, that lofty body does not quite fit the deal, somehow. It's a sort of 5-series Touring on stilts, and those wheels are unfeasibly big.
There's a reason for this. The X5 is an off-roader.
To describe the X5 simply as an off-roader, though, is to miss the point. Americans describe cars such as the Jeep Grand Cherokee or Land Rover Discovery as "Sport Utility Vehicles" (SUVs). The sport part relates more to the activities that the car facilitates, than to the car itself. After all, few would describe a Discovery as "sporty".
The X5, however, is more than a mere SUV - BMW describe it is a SAV, or "Sports Activity Vehicle". This subtle distinction suggests that the X5 is itself an integral part of this sportiness thing. Hence the racetrack interlude above.
In a sense, though, the X5 has been designed back-to-front. You would expect an engineering-led company like BMW to think about function first, then devise a form to suit. Not here: the company's California-based Design Works studio began by deciding what a BMW-flavoured SUV/SAV should look like - a tricky task, given the apparent mutual exclusivity of sporty BMWs and muddy tracks - and only then did BMW work out how to make the form function.
It could have been a massive visual joke, but the designers got away with it. The same goes for the interior, in which you sit SUV-high but surrounded by familiar furnishings - a cosy BMW bungalow which has cleverly morphed into an open-plan house.
Among the house's mod cons are an electric reclining mechanism for the rear seat-backs, which you can operate while standing at the boot door so you can alter the load space to suit the shape of your load, and an automatic garage door-opener with three separate codes. X5 owners are expected to have at least one country retreat as well as their main abode.
And the driving? The X5 blows its rivals right away. At least it does so on metalled roads, with cornering so flat and fuss-free that it defies the normal expectations one holds about the physical laws' limits of jurisdiction.
Most big 4x4s feel woolly in their steering compared with a normal car, and hint that they might trip over their outside front wheels if cornering gets too enthusiastic. The X5 does nothing of this kind, helped by a bank of electronic minders which apply the brakes individually and modulate engine power to keep you pointing in the right direction.
It feels, broadly, like a bigger 5-series with a better view. Rigid, car-like unitary construction helps, partly because it makes dynamic forces easier to control accurately than they are with the truck-like, separate- chassis designs of most 4x4s (which, conversely, are tougher for yanking and towing).
That said, the standard suspension is a touch soft and queasiness-inducing, and it makes the steering unimpressive at straightening itself up after a tight corner. You have to feed the steering wheel back yourself, or else you might drive round in an unintended circle.
Neither criticism applies to the firmer Sport suspension and the attendant bigger wheels, which still give a good ride. It makes the X5 go faster - the standard version is electronically limited to 129mph instead of 143mph, simply because its tyres aren't up to higher speeds.
The V8 is a fine, lusty, but rather thirsty, engine. It emits a great sound from its four tail pipes - a sort of American V8 muscle car sound filtered through ear plugs - and channels its huge thrust via a smooth- shifting automatic transmission with an amusing, but ultimately unnecessary, Steptronic manual override.
There's no secondary set of ultra-low, off-road gear ratios, so owners of Jeeps and larger Land Rover products can retain a little smugness regarding their off-road greater potential, but the X5 copes pretty well off-road anyway. The X5 uses those electronic brake controls to calm spinning wheels, and - in the guise of the Hill Descent Control, first seen in the Freelander - to tip-toe gently down those slippery slopes.
It's no Land Rover Discovery, but it will do for most people's adventures. We'll get the X5 in Britain next autumn - with the less-dipsomaniac 3.0- litre, six-cylinder versions, both petrol and diesel, following the year after.
Prices will be just above those for same-engined, SE-specification 5- series Tourings. For the world's best-driving big 4x4, that's probably not too high a price to pay - even if it is a heck of a lot cheaper in its native America.
Model: BMW X5
Price: pounds 45,000 approx
Engine: 4,398cc V8, 32 valves, 286bhp at 5,400rpm
Transmission: 5-speed automatic gearbox, four-wheel drive
Performance: 143mph, 0-60 in 7.3sec, 17-21mpg
Jeep Grand Cherokee V8: pounds 34,995. Less agile and sophisticated than the X5 but ultimately less stoppable off-road. The V8 Cherokee is brash, fast, very capable.
Land Rover Discovery V8 ES: pounds 35,075. Like the Jeep, the top range Discovery makes the X5 seem expensive. But even its clever flat-cornering suspension can't make it match the BMW's on-road prowess.
Mercedes-Benz ML430: pounds 43,390: BMW money but, like the X5, the M-class is built in the US where cars are cheap. Pleasing drive and adept off- road. The interior is plasticky.