It's been a while since our spy photographers caught the BMW M3 Sedan in action. A black prototype was previously spied lapping the Nurburgring and now a test mule has been spotted in white undergoing an essential winter examination. The change of color indicates the fifth-gen M3 is further into development and a reveal in concept form at March's Geneva Motor Show is a distinct possibility. A small rear spoiler is now evident as are carbon ceramic brakes complete with six-piston calipers at the front axle.

The F80 M3 will be powered by a turbocharged straight-six mated to a dual-clutch transmission. Previous reports suggest it will eclipse the current generation M3's 414 horsepower naturally aspirated V8 by at least 40 horses, with an output likely to be in the 450-500 range. Revised styling for the 2014 BMW M3 should arrive in the form of bigger wheel arches, even more aggressive looking front and rear bumpers, and a unique aerodynamics kit to differentiate the M3 from the F30 3-Series sedan. A reveal of the production model is expected at the 2013 Frankfurt Motor Show in September.