What ever colour it comes.
I'd never buy a new car, so I'd never have the chance of picking the colour. I think when you are looking for cars, the car finds you, not the other way around.
The right one will jump out at you. But....
TBH if I owned a BMW, I would like it to be black or white. Just so I can play Mafia with myself in my head!
Any other car doesn't really matter to me!!