Ahead of its web debut, the BMW M6 Gran Coupe leaks on the interwebs. The photo comes courtesy of a Dutch dealership (via Autogespot) and showcases the M6 Gran Coupe prototype inside a BMW factory.

The test mule sports M6-like side skirts, M ceramic brakes and M mirrors. Design wise, the M6 Gran Coupe builds atop the recently launched M6 and 6 Series Gran Coupe, and if our sources are correct, this will be the best looking M in the current fleet.

The power will come from the same engine as the new M5 and M6, a high revving 560 hp M TwinPower Turbo V8 mated to a high torque 7-speed M-Double Clutch transmission (M-DCT). It remains unknown if BMW will offer a manual transmission for U.S. customers as we have seen in the F10 M5.

The car will incorporate the typical M cues, flared fenders, larger air intakes and wheels, and the signature quad exhaust tips. Since the 6 Series Gran Coupe shares its underpinnings with the 5 Series Sedan, the M6 Gran Coupe model will most likely have more mechanical similarities to the M5 than the M6 Coupe.

When it comes to market in 2013, we anticipate the base price of the M6 Gran Coupe to be around $120,000.