My E39 wagon was Sterling Grey. Pretty easy to keep clean.
Current car is Saphire Black. I know the local touchless car wash operator on a first name baisis.
Saw a carbon black E61 a few weeks ago. Looked sweet in the showroom. My bet would be that it would be a bugger to keep looking sharp.
2015 F30 M Performance Edition, Grey Black Individual, 6 Speed
25 Retired and thoroughly enjoyed Bimmers