[ersin]

Low profile, nondescript, not flashy? Let's see. Get a dark color -- no Melbourne Red or White. Tint the windows, but not too much, say 50%. Get the 18" wheels. Replace the side reflectors with ones painted the same color as the car. Don't leave anything in the car in plain sight; put it the trunk or glove compartment if you have to leave it in the car. This might sound counter intuitive but park it in a well lit place at night and a wide open space in the day. People are less likely to mess with it if they think others can see them.

Lastly, don't sweat it. Most people will know that it's a BMW in any case, but won't know that it's an M3 or even what an M3 is. If you do pull the badges just take off the biggest ///M3 badge (in the back). The dealer will probably do this for you free. And besides, it's just a car. It will get scratched, dented, etc. no matter what you do. Just respect the cars power and be safe.