The BMW X6’s twin-turbocharged six-cylinder diesel is an excellent device in all its other applications, and so it proves in the X6. The 301bhp of the more powerful diesel makes it quick enough, as a claimed 0-62mph time of 6.5sec proves. But it’s the torque – some 443lb ft – that helps to make this engine, and a car as heavy as the X6, so driveable. The rev range is broad and smooth, while the six-speed automatic gearbox makes its shifts cleanly and intelligently.

The 30d is no slouch, either; its single turbo helps to produce 241bhp and the same amount of torque as its larger brethren, with a 0-62mph time of 7.5sec. If you are buying the BMW X6 while wearing your sensible head, then this is the powerplant that is most likely to tick the boxes of performance versus economy and emissions figures.

We didn’t like the electronic gearbox controller at first, but it grows on you; it takes up less room on the console and is intuitive enough

Both engines are sufficiently flexible that they rarely a need to ask the six-speed auto to kick down, but when it does the X6 is fast through itincrements. They are relatively quiet engines, too, and those noises they do make sound cultured and powerful.

Power for the M car comes from a 4395cc V8 motor that puts out 547bhp and 501lb ft of torque, providing the 2380kg X6 with the ability to pass 62mph from standstill in just 4.7sec. That makes this 4x4 faster than the manual BMW M3 coupe.

The engine is a masterpiece, delivering power instantly and in a constant surge. Much of that smooth delivery is due to the six-speed automatic gearbox (there is no other transmission option), but the engine has an impressive level of flexibility through the rev range, never feeling out of its depth.

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Its new diesel equivalent, the X6 M50d, offers equally devastating performance. With 376bhp, it lags behind the petrol car for outright power but counters with a huge 546lb ft, a 45lb ft advantage. This is the figure that enable the M50d to accrue astonishing speed from almost any revs, although some lag is noticeable. Being equipped with an eight-speed auto helps to negate some of this effect by providing closely stacked ratios. For now, BMW's three-litre triple-turbo diesel is unrivalled for power and performance.

The lower powered petrols don't lack for performance, either, but they will remain niche choices at least in the UK, thanks to the workload they have to go through to haul the X6 along, and the subsequently poor economy figures they deliver.

In the dry, the X6 stops well. It is less impressive in the wet, adding 15 metres to the distance in the dry in our tests, though this remains fair for a car of the X6’s bulk.