THE BMW X6 is where SUV meets luxury sports coupe and now it has been given a performance boost with a triple turbo engine.

Pumping out an amazing 381bhp the three-litre diesel in the new X6 M50d is good enough for near supercar acceleration yet its miserly fuel consumption would not disgrace a family hatchback.

Such is the power from this stylish 4x4 that 0 to 60 takes just 5.3 seconds yet this X6 can return an average of 36.7mpg with CO2 emissions of just 204g/km.

At £62,280 the new M50d fits into the X6 line up behind only the 4.4-litre V8 M version and it's a model that designed to bridge the gap between BMW's M Sport variants and the brand's outright high performance derivatives.

Although a large car the X6 is styled as a four seater and it is luxuriously appointed.

Carbon fibre trim across the facia, door cappings and in the centre armrest accentuate the sports credentials.

With independent ventilation all round, leather upholstery and a 6.5-inch widescreen colour display the cabin is as posh as it is technologically sophisticated.

On the road the M50d has an exceptional turn of speed now aided by that third turbocharger which kicks in at 2,600rpm giving seemingly endless power throughout the rev range.

BMW was one of the pioneers of twin turbo diesel engines which combine high and low pressure boosters. The new set up adds a second high pressure system to give even more output under acceleration.

The straight six cylinder engine, also fitted to an M50d version of the X5 priced from £60,325, is the most powerful diesel BMW has produced and its triple turbo technology is a world first on production cars.

For such a large vehicle the X6 is surprisingly nimble and the steering is nicely weighted at all speeds.

An eight speed auto box is standard with rapid fire paddle shifters flanking the steering wheel and with 5,400 revs to go at there is plenty of scope for the car to perform. Sport mode extends the gear shifts and gives it even longer legs.

The surge of power as the third turbo arrives on stream is little short of amazing yet even driven enthusiastically we saw an average of 28mpg on the trip computer.

Take it more sedately and overall the M50d returned 32 to the gallon which makes it an impressive all rounder.

For off road conditions its capabilities are enhanced by hill descent control which adds another string to its bow.

It is more than a match for the likes of the Range Rover Sport and with its overtly bold styling the X6 has a commanding presence.

Air suspension produces an accomplished ride and the growl from the twin exhaust clusters is quite unique giving the M50d its own special feel.

It sits on 20-inch alloys and comes with plenty of BMW M badging including special logos on the door sills while a power bulge in the bonnet leaves little doubt that this is a big car with a big punch.

Options include a full colour head up display at £1,015 and BMW's full media system which incorporates Internet connectivity at £2,365.

In the super coupe cum SUV market the X6 is already in a niche of its own and now with this advanced diesel it has climbed to the top of the technological tree.