The rumors of the BMW 4 Series Coupe to launch at the 2013 Detroit Auto Show are intensifying as a new spy photograp

h is released on  the interwebs with the car almost baring it all near the BMW headquarters in Munich. With almost to camouflage, the side design is revealed which surprisingly features a functional vent. New side mirrors with signal indicators, M Performance brakes, and a small badge indicating that we are looking here at the Sport Line model are also visible in this photograph.

Photo Source: Carscoop