BMW never really wanted to apply its highly respected M badge to its SUVs, but the success of high-performance rivals offered by Mercedes-Benz and Porsche has forced the Bavarians to produce not only an X6 M but also an X5 M.
They will be the M division's first SUVs, the first turbocharged models, the first that are not rear-wheel drive and – horror of horrors – the first with automatic transmissions.
Australian enthusiasts will be able to buy the X6 M from the fourth quarter of 2009, but BMW Australia has no plans to introduce the X5 M in this country.
Revealed for the first time at the New York auto show on Sunday, the SUV M twins are powered by a highly-modified version of BMW’s 4.4-litre twin-turbocharged V8 engine that was introduced to the SUV line-up in the form of the X6 xDrive50i in January.
However, while the standard engine produces 300kW of power at 5500rpm and 600Nm of torque from 1750-4500rpm, the M engineers have extracted huge increases in performance, resulting in figures of 408kW at 6000rpm and 680Nm from 1500-5650rpm.
The result is staggering on-road performance, with 0-100km/h arriving in just 4.7 seconds – some 0.7 seconds faster than the xDrive50i – while top speed is speed-limited at 250km/h (or 275km/h with the optional M Driver’s Package fitted).
BMW claims that both of the M SUVs set new dynamic performance standards in their class, which includes the 375kW/630Nm 6.2-litre V8 Mercedes ML63 AMG and the mighty 404kW/750Nm 4.8-litre V8 twin-turbo Porsche Cayenne Turbo S.
Despite having much more torque, the slightly beefier Cayenne performance leader comes up slightly short in acceleration, being 0.1 seconds slower to 100km/h, while the less powerful AMG Benz is 0.3 seconds slower again and is even nudged out by the burly 230kW/750Nm 5.0-litre V10 turbo-diesel VW Touareg R50.
The big X6 M officially matches the 0-100km/h times of 4.7 seconds for both the 309kW/400Nm 4.0-litre V8-engined M3 sedan and the 373kW/520Nm 5.0-litre V10-engined M5 sedan – both fitted with the faster-shifting SMG twin-clutch transmission.
Reports out of the US suggest that the X6 M is faster around the daunting 22km Nurburgring race circuit than the old six-cylinder E46 M3 sedan, so the M boffins have clearly done their homework on the steering, suspension and brakes to produce that sort of performance from a vehicle weighing 2380kg.
Like all M cars, the heart of the new SUVs is the engine, and BMW’s new twin-turbo V8 petrol – called the M TwinPower Turbo – is said to be the first in the world with a single exhaust emission manifold joining both rows of cylinders.
The twin-scroll turbochargers and the catalytic converters are positioned in the V-section between the two rows of cylinders, which BMW claims ensures spontaneous and direct response as well as a linear surge of power for a consistent flow of torque at all times.
It says that, by reversing the flow of gases through the engine from traditional arrangements, the intake and exhaust ducts are shortened and widened, resulting in minimised pressure losses on the exhaust side to virtually eliminate turbo lag while maximising combustion efficiency and power output.
Of course, the patented system introduces another new acronym, being known as Cylinder-bank Comprehensive Manifold (CCM).
BMW says the instant onset of power is accompanied by unique engine sounds that accentuate the quick-revving characteristics and transforms “from relatively calm to extraordinarily intense as the boost and revs build from idle”.
As well as employing two high-capacity water-to-air intercoolers while EU5 emissions standards are reached thanks to direct-injection and energy-saving systems such as regenerative braking, on-demand control of the electric fuel pump, a detachable air-conditioner compressor and a flow-controlled supply of hydraulic fluid to the anti-rollover system.
The BMW X6 M has an overseas average fuel consumption figure of 13.9L/100km – only marginally worse than the local figure for the X6 xDrive50i (13.8L/100km).
The standard six-speed auto transmission has been modified for faster shift times and can be manually operated by aluminium steering wheel paddles (right for upshifts, left for downshifts). A launch control function is available for maximum acceleration.
BMW M has also gone to work on the steering and suspension, both of which can be altered by the driver from the cockpit like other M models. Air suspension and self-levelling on the rear axle as well as electronically adjustable dampers and active anti-roll control are standard.
High-performance brakes with four-piston callipers take care of the stopping department and both models ride on standard 20-inch light-alloy wheels with different-sized run-flat tyres front and rear. Other standard features include bi-Xenon dual headlights, daytime driving lights and adaptive brake lights.
Inside, they come with M seats and other M-specific cockpit features such as leather steering wheel, footrest, door sills and an instrument cluster with a variable pre-warning field in the rev counter, specific vehicle function displays and white illumination of the display units. The 230-Watt audio features 12 speakers.
Externally, the X5 M and X6 M feature almost identical bonnets, headlights and front airdam design with large air intakes for extra cooling, as well as special gills in the front fenders, diffusers at the rear, quad tailpipes and body-colour side skirts.
BMW Australia will announce pricing closer to launch, but the X6 M will obviously far exceed the xDrive50i’s $146,000 and probably the ML63 AMG’s $167,500 as well, but should be well short of the $234,000 Cayenne Turbo.