BMW Australia has introduced its first twin-turbo V8 under the bonnet of the new X6 all-wheel-drive coupe.

The double-boosted bent-eight gives the X6 xDrive50i a rocket-like launch with 600Nm of torque on tap and peak power of 300kW.

This 4.4-litre unit has direct petrol injection and a low-inertia turbocharger on each cylinder bank, spinning up to 175,500rpm.

All 600Nm of torque is available from just 1750rpm through to 4500rpm, while the engine generates peak power at 5500rpm.

There is enough force to sling the 2190kg AWD from 0-100km/h in just 5.4 seconds, which is up there with far lighter performance sedans and coupes.

Customers will have to a pay a privilege to experience the potent X6, with an asking price of $145,000.

It sits above the $120,530 xDrive35d at the top of the X6 range, which also contains the entry level xDrive35i at $114,705.

The new twin-turbo V8 has even more torque than the diesel six that powers the 35d, which has a respectable tally of 580Nm and a power total of 210kW.

It is also a significant step up from the 35i’s twin-turbo six-cylinder which produces 225kW and 400Nm of torque.

As you might expect, the new twin-turbo V8 X6 has quite a thirst, consuming 19.6L/100km around town and 10.4L/100km for country cruising, translating into a combined figure of 13.8L/100km.

This compares the relatively frugal 35d diesel at 9L/100km and the 12.1L/100km of the 35i petrol six.

As with other X6 models, the twin-turbo V8 runs BMW’s full-time xDrive AWD system that quickly shifts drive from front to rear axles as required.

It also features BMW’s Dynamic Performance Control, which is able to transfer power across the rear axle.

This form of electronically controlled differential is able to direct the amount of power required to each wheel to keep the car as stable as possible in corners.

BMW says the system is especially useful in faster corners, sudden high-speed maneuvers or when the driver lifts off suddenly, giving the driver more control.

The company has also developed more potent brakes for the twin-turbo V8 X6, taking into account its improved performance and increased bulk.

The 385mm discs are grabbed by single-piston aluminium calipers.

The 50i X6 comes standard with self-leveling pneumatic suspension and sits on unique 20-inch light alloy wheels.

The exterior differences between it and other X6 models are subtle, with the main points of difference being chrome window surrounds, a titanium radiator grille surround and dual rectangular chrome exhaust pipes.

On the inside, the range-topping X6 is fitted with premium leather trim, and owners can choose from two wood-grain and two aluminum dash and door trims.

Standard features include keyless entry and ignition, head-up information display, four-zone climate control, 16-speaker hi-fi system, steering-wheel-mounted gear shift paddles and anti-dazzle mirrors.

The X6 is based on the second generation platform of the more practical X5 AWD and, like that vehicle, is also built at the Spartanburg plant in South Carolina.

It shares no body panels with the X5 though, and is 23mm longer, for a total of 4877mm, and is 50mm wider, measuring 1983mm across.

It has 570 litres of boot space with the rear seats in place, which is more than some of its competitors. While this looks adequate on paper, the load space is compromised by the coupe rear and the rear of the boot is quite shallow.

When the rear seats are folded down, the load area opens up to 1450 litres.

There are only four seats and although there is limited headroom in the back, BMW is quick to point out that it has more rear headroom than a Mercedes-Benz mid-sized C-Class.