The M-enhanced version of BMW’s svelte 6-Series Gran Coupe has been one of the worst kept secrets of the year, with barely disguised prototypes, teasers and official comments all making it obvious a new M car was in the works.
Now, BMW has finally revealed its new 2014 M6 Gran Coupe, ahead of a sales launch early next summer. Like the latest versions of the M5 and M6 coupe and convertible duo, with which it shares a platform, the M6 Gran Coupe follows a familiar path of performance tuning.
Up front is a twin-turbocharged 4.4-litre V-8 engine rated at 412 kilowatts and 678 newton-meters of torque. Power is sent rearward, first to a seven-speed dual-clutch transmission and then to a unique limited-slip differential before reaching the rear wheels.
The special differential, dubbed the Active M Differential, is an electronically controlled multi-plate limited-slip differential programmed to optimise traction, stability and sporting character. The locking force within the differential is varied continuously between 0 and 100 per cent.
In addition to the data provided by the car’s electronic stability control system, the Active M Differential’s control unit also takes into account the position of the accelerator pedal, the rotational speed of the wheels and the car’s yaw rate. Every driving situation is therefore analysed so that any loss of traction on one side of the car is identified early and the degree of axle lock adjusted as required.
The engine, too, is a marvel of engineering. It produces about 10 per cent more output than the old M V-10, but the real story is torque, which is up 30 per cent and delivers its peak rating from 1,500 all the way up to 5,750 rpm. The rev-limiter is set at 7,200.
The key to the engine’s prowess is a pair of turbochargers nestled in the V between the two cylinder banks in a reverse-flow layout. This layout results in an unusually compact engine where the intake is moved outboard and the exhaust inboard. The lengths of intake and exhaust tracts are also shorter, helping to reduce pressure losses.
The engine is also aided by direct fuel injection, a relatively high fuel to air compression ratio of 10:1 and BMW’s Valvetronic valve timing technology. Other performance specs of the latest M car include aluminium-intensive suspension, reinforced chassis mountings, electronically-controlled shock absorbers, speed-sensitive hydraulic power steering and M-specific stability, anti-lock braking and transmission programming.
At its peak, the M6 Gran Coupe will rocket to 97 km/h from rest in just 4.1 seconds and easily reach its electronically-limited top speed of 250 km/h. To bring it back to rest, the car gets massive 15.7-inch brake discs up front and 15.6-inch discs at the rear. These are composed of steel and aluminium and are gripped by six-piston fixed callipers painted blue metallic and featuring the M logo. They’re housed within a unique set of 20-inch forged wheels.