I got both black n white cars..
1 black car is 11 yr old, glossy. The white one is just 1 month old. all i can say is, white is harder to maintain altho i send for washing every 4-5 days.. after raining, there is some water droplets pattern on the paint and its very hard to hide that.
But my black car, just send for wash once every month but still looks wet and glossy even after raining.. black paint can hide water marks better than other paint, as long as u dont drive it thru muddy puddle of water la..