Originally Posted by Asbjørn
I personally do not regard any regular AMGs/Audi RS/Z4 as much as racecars as an M3.
Grattan Raceway | 2.2 miles
Audi RS5 1:28.48
Porsche Boxster S 1:29.10
BMW M3 1:30.05
Mercedes-Benz C63 AMG 1:30.06
I hate to magazine race but here's an interesting data point from automobile mag. Audi RS5 got better lap times than boxster s, m3 and c63
Interesting aside is their comment that Boxster S was the only one that could go all day.