BMW has in recent years developed many cross-over "niche" vehicles namely the X6, the 5 Series GT and X1M. BMW’s latest model is a crossover sedan-coupe in the form of its 6 Series Gran Coupe.The new model is an interesting take on the F13 6Series coupe and sports frameless windows. Our spies spotted the new model undergoing testing.3 SERIES GRAN COUPE?The Gran Coupe version is a bit longer than the 6 Series coupe. When unveiled in 2010 the car was more than five metres long; reality has now shrunk it to 4.9m.The German automaker is so fond of the Gran Coupe idea that it’s looking to develop a Gran Coupe version of its next 3 Series. According to our sources the new model could have the designation 4 Series Gran Coupe with an M4 Gran Coupe in the works.The 6 Series Gran Coupe is expected to be released globally in 2012.