A good number of the guys who got the M5 can't drive very well, or haven't driven manuals in YEARS, as far as I've seen. But I'd lean towards the M3 in any road race...but some of those drivers have done some dumb sh-- too. One the street, M5. At the track M3. The M5 will do better on long straights, but the M3 will outbrake it, outhandle it, and get on the power sooner. But, it will still be up to the driver to make that happen.