Originally Posted by kyleb350
Well, an M3 is a track car out of the box. I think if you're into actually building a track car, I'd go with the 135i and mod it with the money you'll save by skipping on the M3.
OK, A M3 not really is a track car in my book but it handles rather well when using on a track. A 135i has a great engine and can be nice on a track as well but the electronic LSD in the 135i is not my cup of tea compared to the M limited slip diff and if you are going to mod the 135i be aware of overheating issues.
I'd choose the M3 but the 135i is a bargain and 'new'.