This would have been my entry if I had the time to finish it, but by the end I got too pressed for time..
Basically,
Enlarged S4 wheels
Lowered (with coilovers if it were real)
Coupe conversion and drop top
Partial debadging on grille
Cobra Clubsports racing seats
if I had the time I might have done Audi R8 (Le Mans race car) wheels and experimented with an all wheel drive burnout... I still want to finish this at some point