It should come as as no surprise that since the series version of the Gran Coupe has been revealed, the M version is now out winter testing. The spies over at CarScoop have snagged some photos of the four door coupe in the white stuff. Rumored to be BMW M ‘s most powerful and luxurious offering the M6 Gran Coupe will future the S63tü engine as found in the M5 and M6 but with a slight up tune in the neighborhood of 25 hp totaling 585hp. The Gran Coupe M version will have a carbon fiber roof with similar contours as the recently unveiled M6 Coupe as well as being only offered with the 7 speed Getrag DCT. Sources point to a fall preview and possible Spring 2013 launch. More photos at CarScoop.