On display at the AMI Leipzig show is an example of the BMW base paint steps for the 1 Series. This color was Mineral White which is an option for X1s made at Leipzig.
Here are the six paint stages of BMW:
1) Steel Panel
2) Cathodic Dipping Paint. Rust Protection.
3) Primer coat. Protection against stone-chipping. Color base for base coat.
4) Water based coat of final color. First layer.
5) Water based coat of final color. Second layer.
6) Clear coat. Brilliance and resistance against environmental influence.
Source: Bimmerpost