To anyone that is trying to side the M3 as just some luxury car, don't forget BMW's advertisement:
BMW makes this out to be some class-leader track car. It sorta is, but it definitely ISN'T just some luxury car with a V8. BMW relies on image and prestige more than anything, which I can see half of you fanbois fell for. If you want that look of class and styling, BMW makes beautiful-looking cars all over their lineup. Just don't come in here pretending that you know the Mustang GT will just fall miles short in performance. I guarantee you it won't, and you will be in for a rude awakening when you go up against one (especially if it has some drivetrain mods).
I ordered my 2011 M3 before the current Mustang GT was out. I don't regret it, in hindsight, but for this new generation I think BMW isn't giving me what I want (a NA high-powered V8 I can take to the track in a sports car package). Sure the new M3/M4 will be fast and styled nice, but it's not the same sort of drivetrain. I've raced in Formula Renault 1600 and other great track cars, and having a NA engine is a thing of beauty.
Further, I plan to mod my car, and starting with such a great base platform with gobs of cheap performance parts to boot, the Mustang GT will win hands down, AND FOR HALF THE PRICE!
I love BMW. The heritage, the styling, the attention to detail, I'm still sold; just not on spending so much on their sports cars anymore. I think at this point I'm looking at a 2 year lease on an M235i or a 550i w/ some stiffer springs while I wait for a good deal on my new S550 Mustang GT.