BMW’s grandest four-door coupe

BMW has added a third model to its high-end M6 line-up, slotting a more practical four-door in alongside its existing two-door coupe and convertible.

The $299,500 M6 Gran Coupe, as the model is known, will compete at the higher end of the four-door fastback coupe market, up against the likes of Aston Martin’s $341,600 V12-engined Rapide, the soon-to-be-updated $346,100 twin-turbo, V8-engined Porsche Panamera Turbo, $276,400 4.7-litre V8 Maserati Quattroporte Sport GT-S MC Sportline, and even the $263,000 Mercedes-Benz CLS63 AMG sporting a twin-turbo 5.5-litre V8.

According to BMW, buyers will look at the four-door M6 based on a “strong focus on emotion and athleticism”.

“It’s a perfect combination of high-performance sportscar and luxury four-door coupe” Jorg Bartels, Munich-based BMW M’s head of sales operation management said. “You don’t have to have a thoroughbred Ferrari any more.”

At the heart of the M6 Gran Coupe is a high-revving, 4.4-litre V8 with a tricky combination of cross-flow exhausts feeding into a pair of turbochargers nestled in between the wet sumped engine’s banks.

It produces the same 412kW of power high in the rev range, and 680Nm of torque pretty much right across it, as its cheaper coupe and more expensive convertible siblings.

Drive is sent to the rear wheels via a seven-speed dual-clutch transmission, while an active locking differential helps to maximise traction through the rear wheels.

Every element of the M6 Gran Coupe is tuned for performance. The small lip on the boot lid, for instance, increases high-speed braking stability, ensuring the back of the car does not wriggle around while rapidly bleeding off speed.

The M6 Gran Coupe is not a four-door clone of its two-door siblings.

For starters, the four-door version stretches an extra 113mm over the coupe, and despite the carbon fibre roof – the only other car to get one is the M3 – the Gran Coupe weighs in at 1950kg, 100kg more than the two-door car.

At 5011mm, it is almost as long as a range-topping 7 Series, which starts from $205,700. While the wheelbase is longer, the track front and rear remains the same as the other cars in the M6 range.

To compensate for the extra weight, the Gran Coupe has a bespoke suspension tune, including a 15 per cent stiffer front end than the two-door.

The M6 Gran Coupe gets similar M-tuned front and rear axles as its siblings, with no rubber dampers between the suspension mounts to ensure maximum feel for the driver.

The brakes are beefy. Up front, six-piston fixed calipers grab onto 400mm vented floating discs – as big as the alloy wheels on a Mini Cooper -- while down the rear, floating single-pot calipers bite on 396mm vented discs.

Fuel use is officially 9.9 litres per 100 kilometres on 98 RON fuel, which is good considering the high performance of the vehicle. Carbon dioxide emissions are rated at 232 grams per kilometre.

Helping the cause is an idle-stop system that switches the big V8 off while the car is stopped in trafficStandard equipment is generous. There’s a big colour screen mounted in the middle of the dash, and the extremely adjustable front seats include heating and cooling functions.

Owners can even share internet services with other devices via a smartphone paired with the M6 Gran Coupe’s Bluetooth system.

Safety runs to six airbags, active front-seat headrests, cruise control with a braking function, and a speed limiter.

There are also a number of driver assist systems. These include an M Dynamic Mode that allows the driver to set suspension, steering and throttle responses, a dry braking function, launch control, and start-off assistance that quells wheelspin from a standing start.

For the keener pilot, all driver assistance systems will switch completely off.

You even get an advanced driving course thrown in with the car.

The Gran Coupe gains a few more interior appointments over its siblings. That includes dual-zone climate control for the rear seats, roller sunblinds in the rear, a big strip of high-mounted LED stop lights across the top of the rear window, a swathe of real leather in the artificial leather roof trim that accentuates the dipped roofline, cupholders in the rear-seat armrest, and for added load space convenience, a 60:40-split rear seatback.

The M6 Gran Coupe runs the same 9.5 inch-wide 20-inch wheels on the front as the other M6 models, and 10.5 inch-wide rims at the rear.

BMW will offer a $12,000 performance package for the M6 Gran Coupe that, as well as adding 11kW of power to the engine to make 423kW, drops the suspension by 10mm. It also beefs up the springs and dampers, remaps the electronic stability control, retunes the rear differential, and modifies the exhaust system.

Ceramic brakes are also on the options list for $24,500. As well as reducing unsprung weight by 20 per cent, the discs should last the life of the vehicle – as long as you stay off the race track, BMW said.

2013 BMW M6 pricing*

Coupe	$292,500
Gran Coupe	$299,500
Convertible	$308,500

*Excludes on-road costs.