First, there was the Mercedes-Benz CLS. And it was good. Then, the Audi A7. That was also good. Now, Internet, meet the third contender for the crown of ultimate luxo-four-door-coupe-thingy: the BMW 6 Series Gran Coupe. It\'s the first four-door coupe BMW has ever built, and its launch next year will kick off a Teutonic three-way tussle so explicit it\'d make the Internet\'s most liberal adult film purveyors blush.As you can see, the Gran Coupe is a stretched Six, some 22cm longer than the Coupe, 4cm longer than the A7 and a whopping 7cm longer than the CLS, and features a 4+1 seating system as in the Audi A7. The wheelbase is 11cm longer to allow for a \"noticeable increase in legroom\" for the rear passengers, which will come as a relief to anyone who\'s travelled in the back of a 6-Series on a long journey.That long, low and wide stance with short overhangs - and driver-focused cockpit - shows us it has BMW\'s driving DNA etched into its flanks, though whether it can offer up any more joy than the capable-but-anodyne coupe and convertible versions remains to be seen.The 6 GC features electronically controlled dampers, anti-roll stabilisation and electronically controlled anti-roll bars to reduce roll during what BMW euphemistically refers to as \"fast cornering\".Engine wise, you\'re looking at two six-cylinders - the 320bhp 640i and the torquey-yet-frugal 313bhp 640d - along with the range-topping 4.4-litre twin-turbo V8 of the 650i. Essentially a detuned version of the M5\'s powerplant, this puts out a very, very respectable 450bhp and 479lb ft of torque, and together with optional ‘xDrive\' all wheel drive, will do the 0-62mph sprint in 4.5 seconds. That\'s 0.1 slower than the 518bhp Mercedes CLS 63 AMG. That\'s scary-quick. BMW will only offer an eight-speed auto with the new Gran Coupe, along with standard equipment including electrically adjustable leather seats, two-zone climate control, 18in alloys, and a natty HiFi system. As usual, you can demonstrate your individuality - and burgeoning wallet - on the options list, including the M Sport pack. That adds aero body parts, a sports exhaust, 19in wheels (with optional 20s), sports seats and lots of M badging.