I have these 3 colour cars. Gunmetal grey, black and polar sliver. I like cleaning these regularly aswell as polishing and waxing them. The problem I have is the black car is too much hassle to keep clean!!. The polar sliver is good as it does not get as dirty or show as much dirty as the black merc. I also have a Gunmetal car is this the best because it get dirty but you cannot see it as much as the others? Which is the best colour?. Thanks.