Believe it or not white is one of the easiest colours to keep looking good. Yes it shows dirt but it is easy to wash, doesn't show stonechips and also hides swirl marks from polishing and everday day scratches that you pick up. I last had a white car in 1989 when it was at the peak of its popularity here in the UK and remember well how much easier it was to look after.

I don't think I'd fancy a white Porsche though.