You will probably have to co-sign a contract with someone who has credit. Had a similar issue. Also, you need to deal with insurance considerations.
With that said, if you're making your own money at 16 and are successful enough to afford an M3 I would expect you to know how to finance something. Lastly, I don't think an M3 is too much car for a responsible 16 year old...but consider where you go from there after the M3....sometimes its more rewarding to wait for the car you want even if you can afford it. Good luck, and if you end up getting the car, be safe.