This was a quick study for a sedan body design on the Traxxas 1/16 Rally chassis. This shell captures the legendary Audi 90 that utterly dominated the GTO class in the 1989 IMSA series.
Updated with massive side vents in an DTM approach to underbody aerodynamics, and then draped around the relatively massive wheels. Perhaps with different rear wings and different graphics the sedan shape might be universal enough to look like a proper DTM or Supercar racer.