UNIQUE styling, SUV proportions, twin-turbo engines, technology-enhanced sports car handling and ultra-niche positioning are the hallmarks of the BMW X6 ‘Sports Activity Coupe’.

On sale on August 11 from $114,705, the E71 series X6 is a four-door, four-seater wagon-cum-coupe luxury SUV, with the Range Rover Sport being its nearest conceptual competitor.

BMW describes it as ‘a blend of the strengths of the BMW X5 and the BMW 6 Series Coupe’.

In fact, the X6 is derived from the second-generation E70 series X5 SUV – itself loosely based on the current E60 5 Series – and is similarly built at BMW’s Spartanburg, South Carolina production line.

However, while X6 and X5 share much of their mechanicals, understructure and interior, they have no body panels in common, while there are also specific differences in areas such as the rear track.

Dimensional differences include the X6’s 4877mm length (23mm more than the X5) and 1983mm width (up 50mm).

Two well-specified all-wheel drive models will be available from launch, with more to follow later: the twin-turbo in-line six-cylinder petrol known as the xDrive35i, and the xDrive35d – employing a variation of the twin-turbo in-line six-cylinder diesel that debuted in the X5 3.0sd in the beginning of the year.

January 2009 will see the debut of the twin-turbo V8-powered xDrive50i.

In BMW parlance, ‘xDrive’ refers to its four-wheel drive system while the ‘35’ denotes the current most powerful versions of each 3.0-litre engine on offer – which, for the X6, means twin-turbocharged. This new nomenclature is expected to spread to future X5, X3 and (as yet unconfirmed) X1 models.

The petrol engine is the twin-turbo 3.0-litre already seen in the 135i Sport and 335i models. BMW says it delivers the performance of a V8 with the efficiency of a naturally aspirated ‘six.’

It includes second-generation high-precision direct injection and Bi-VANOS variable valve technology (but not Valvetronic as the turbo application eliminates intake vacuum issues), as part of BMW’s Efficient Dynamics package.

With the aid of two same-size turbochargers working on three cylinders each, outputs are 225kW of power at 5800rpm and 400Nm of torque at 1300 to 5000rpm, resulting in the 2070kg xDrive35i taking 6.7 seconds to reach 100km/h, using 12.1L/100km of premium unleaded petrol on the combined cycle and emitting 286g/km of carbon dioxide.

The all-aluminium 3.0-litre twin-turbo diesel X6 xDrive35d boasts the world’s most powerful six-cylinder engine of its type, as well as one of the lightest at 210kg. Peak power is 210kW at 4400rpm and torque tops out at 580Nm between 1750 and 2250rpm.

However, in contrast to the petrol, the diesel’s two variable turbos are of different sizes. The smaller one works in reducing low-rev turbo lag thanks to its low inertia, while the larger turbine gradually takes over as revs rise for a stronger power delivery right up to the rev limit.

The result is a 0-100km/h time of 6.9s for the 2110kg xDrive35d, while the official combined average and CO2 ratings are 9.0L/100km and 237g/km respectively.

Both X6 engines are mated to the ZF six-speed automatic transmission common to most BMWs, recalibrated and retuned for ‘sporty’ response. Steering wheel paddle shifters also make their first appearance in this level of BMW. No manual gearbox will be offered, despite the car’s sporty aspirations.

BMW’s xDrive 4WD system uses a centrally mounted, electronically activated, multi-plate clutch to distribute drive between the front and rear axles as needed, determined by the predictive stability and traction control, and advanced anti-lock and brake technology systems, collectively known as DSC+.

The X6 also introduces BMW’s new ‘Dynamic Performance Control’ (DPC) rear differential, which, according to the Germans, pushes out the dynamic envelope for all-wheel drive vehicles by counteracting the inherent mild understeer for a more RHD-like neutral attitude.

This is done by switching power between the left and right rear wheels, for improved traction and lateral acceleration, leading to lighter and more precise handling.

The system links the standard rear differential with a mechanical planetary gear set and an electronically-controlled multi-plate clutch for each wheel, and processes data such as the yaw rate, wheel speeds, steering angle and engine torque in order to react immediately.

Torque distribution is therefore freely dished out in varied amounts as required, to quell understeer and oversteer, as well as increase directional stability when accelerating in a wide variety of adverse conditions.

DPC also improves traction by supplying more power to the wheel with the greater amount of grip – even when the vehicle is coasting. BMW says that torque differences hitting 1800Nm can be actively created between the left and right wheels.

As a result of DPC, the X6’s track is 56mm wider than the X5, precluding the fitment of the latter’s alloy wheel range.

The rest of the running gear is pure X5, with double wishbones in the front and BMW’s multi-link arrangement at the rear.

An optional Sport Package with Adaptive Drive employs active hydraulic anti-roll bars to mitigate roll during cornering and features electronically adjustable dampers for more athletic dynamics.

To recap, xDrive is BMW’s 4WD system that uses a centrally mounted, electronically activated, multi-plate clutch to distribute drive between the front and rear axles as needed, determined by the predictive stability and traction control, and advanced anti-lock and brake technology systems, collectively known as DSC+.

Steering is via a hydraulically activated rack and pinion design, with BMW’s variable ratio Active Steering feature available at extra cost.

Despite the plunging roofline, BMW points out that the rear seat can comfortably accommodate the ‘6-foot 4-inch’ frame of design head Adrian van Hooydonk. At 946mm, headroom exceeds the 6 Series and Mercedes-Benz C-Class by 44mm and 4mm respectively.

Luggage space extends from 570 litres (X5: 620L) to 1450L (X5: 1750L) with the split-fold rear seats in the down position.

The X6 is closely aligned to the X5’s up-spec Executive level and therefore includes adaptive bi-Xenon headlights, a USB audio/media interface, a higher-range sound system, heads-up digital instrumentation and – of course – run-flat tyres, as well as a full range of active and passive safety items.

BMW expects to sell the X6 to buyers who want the physiology and consequent commanding seating position of an SUV, but want sleeker styling and sports-car dynamics.

Although snatching some people from the X5 customer base is inevitable, the company believes that most customers are likely to come from rival luxury SUVs such as the Range Rover Sport, Porsche 911 and Cayenne and Mercedes-Benz ML, as well as the Mercedes CLK, CLS and E-Class, Audi A5, Jaguar XF and Maserati.

Only 300 X6s are slated for import this year, owing to production capacity restrictions.