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.
2014 F31 Estoril Blue, MSport Line, M Performance, Premium, Executive, and Rear Comfort packages
2011 E90 328 xdrive - Space Grey on Saddle, Executive Package, Premium Package
22 Retired and thoroughly enjoyed Bimmers