THE fastest production BMW to ever land in Australia has arrived in showrooms, mixing blistering twin-turbo V8 action with cosseting comfort.

A grand tourer in the grand style and spiritual successor to the 1980s 635 CSI, the new M6 Coupe is even faster in the 0-100km/h sprint than the thundering M5 sedan that arrived here earlier this year, even though they share the same 412kW 4.4-litre engine and seven-speed dual clutch transmission.

While the M5 reaches the highway speed limit in 4.3 seconds, the M6 Coupe pips it with a 4.2-second dash – also faster than arch rival Mercedes-Benz’s CLS 63 AMG and CL 63 AMG (both 4.4 seconds in standard form).

Even the two-tonne M6 Convertible can do the dash in 4.3 seconds – half a second faster than the current M3 and twin-turbo six-cylinder Z4.

BMW Group Australia managing director Phil Horton said the M6 opened a new chapter in the history of BMW M division, which this year celebrates its 40th anniversary.

Priced at $292,500 (plus on-road costs), the M6 Coupe carries a $63,000 price premium over the M5, while the M6 Convertible – at $308,500 – is the second most expensive BMW in Australia, sitting only below the $391,500 flagship 760iL sedan.

The M6 models are about $60,000 dearer than the 650i Coupe and Convertible on which they are based, and which made their Australian debut almost a year ago.

BMW Group Australia expects to deliver up to 30 M6s this year, and next year to beat its previous best full-year sales performance of 65 M6s, set in 2006.

However, the company believes its more affordable M5 will outsell the M6 by more than two to one.

The M6 Coupe and Convertible will be joined in Australia late next year by a similarly M-enhanced 6 Series Gran Coupe that will get the same 4.4-litre V8 and auto transmission from BMW’s M Performance hot shop which is celebrating 40 years in business.

Like previous 6 Series generations, the new model range shares most of its underpinnings with the 5 Series, including the mechanicals transplanted from the M5.

The M6 makes extensive use of light-weight body materials to trim kilograms. The roof is of carbon fibre, saving 20kg and lowering the centre of gravity.

The bonnet and doors are fashioned from aluminium, while the front mudguards are plastic.

The boot lids are made of a fibreglass composite, as is the roof cover for the convertible’s folding softtop.

Despite this, the Coupe and Convertible both tip the scales on the high side, with the coupe coming in at 1850kg and the convertible approaching two tonnes.

However, the coupe is about 20kg lighter than the steel-roofed M5, helping to give the M6 an acceleration advantage.

Apart from the contoured carbon fibre roof, which remains unpainted for effect, the M6 is distinguished from other 6 Series variants by quad exhaust pipes and blacked out kidney grille with an M6 badge.

The M6 is also 25mm wider in the wheel arches to accommodate the big 20-inch alloy wheels.

Oddly, the wheelbase is 4mm shorter than the standard 6 Series, attributed to some adjustment of the front chassis.

The heart of the M6 is the big bore S63 V8 that, uniquely in this BMW development, has its twin turbos nestled in the engine’s ‘V’ in a cross-engine arrangement to shorten the plumbing and generate high turbine speed.

BMW says this delivers the best driving response of any turbo vehicle on the market.

The maximum 680Nm of torque comes on tap from 1500rpm and holds to 5750rpm – one of the widest, flattest torque curves of any car.

The engine is not only a sterling performer at low revs but can spin to more than 7000rpm, with the 412kW peak power arriving at 6000rpm.

Despite the 30 per increase in torque and 10 per cent improvement in power over the previous M6 that was discontinued in 2010, the new powertrain delivers a 30 per cent improvement in fuel economy, coming in at 9.9 litres per 100km in coupe form and 10.3/100km in the convertible.

The power is delivered to the rear wheels via the seven-speed dual-clutch transmission, instead of the eight-speed ZF torque converter unit used in the standard 6 Series.

The driver can select from a number of throttle, transmission and steering settings to create two sports driving modes to taste which can be selected from two buttons – Mode 1 and Mode 2 – on the steering wheel.

The selections can include turning off the ESC, traction control and other ‘nanny’ safety technologies for track work.

An ‘active’ differential uses data from yaw sensors and other gadgets from the ESC system to pre-empt changes in rear wheel traction, such as when pitching into a corner, and adjust the drive distribution and traction control braking force to the wheels accordingly.

The rear chassis is fixed directly to body instead of being isolated through bushes – race car style – with an extra metal plate helping to reinforce the rear body work.

BMW says this has the advantage of delivering a more rigid suspension system, and says it has no detrimental effect on noise, vibration and harshness.

Against the trend to electric-assisted power steering, the M6 steering remains hydraulic, which the company says allows better highway feel, more direct steering ratio and fewer turns lock to lock.

Standard equipment includes adaptive LED headlights, dynamic damper control, leather, internet, lane departure warning, blind spot warning, surround-view parking assist, TV tuner voice recognition and heated and ventilated front seats.