6-Series Gran Coupe will debut sometime in 2012 - a late-comer in the four-door premium coupe category dominated by the Mercedes-Benz CLS and the Audi A7 Sportback.

Our colleagues over at Motor Trend have the scoop on the upcoming 6-Series four-door Gran Coupe.

Originally debuted as the Gran Coupe Concept last year, the 6-Series-based model has been slated for production and will debut sometime in 2012.

The 6-Series Gran Coupe will share the same wheelbase as the 5-Series at 116.8 inches/2967 mm, as opposed to the shorter 6-Series wheelbase length. But the car will be about 3.5 inches/ 89 mm shorter than the 5-Series at 54 inches/1372 mm, and wider too, at 74.9 inches/1902 mm. A lower and wider stance like the 6-Series coupe/cabrio models. Total length will outdo its arch-rival, the Mercedes-Benz CLS, by 2 inches/51 mm and come in at 197.1 inches/5006 mm.

The four-door coupe will feature frameless door windows but the car will have a B-pillar.

To save weight, the doors and bonnet are made of aluminum while special plastics are used for the front fenders and boot lid.

The 6-Series Gran Coupe will also be offered with the xDrive all-wheel-drive system. Engines expected include those already available in the 6-Series.

Gallery: Details emerge on BMW 6-Series four-door coupe