this is something i got a long time ago from this board, kept it on file, shows no ///M3
There will be a 1-7 series indeed...
The Even number series will be the Coupes, the Odd numbered series will be the 4 doors, or wagon/hatch models.
1 Series - 2 door hatch, 4 door wagon (not to be sold in the US reportedly.)
2 series - 2 door cabrio, 2 door coupe, M2
3 series - 4 door sedan
4 series - 2 door coupe, 2 door cabrio, M4
5 series - 4 door sedan, M5
6 series - 2 door coupe (2+2), M6
7 series - 4 door sedan (or iL for limo if you prefer)