yip yellow is the only colour for me, taking delivery tomorrow of my yellow and black cooper, i think the yellow and white looks cool too. The main reason i like the black is cos it is a better contrast with the yellow and i like the way it almost makes the roof disappear... from the distance, in a dark area, with your eyes squinting, and a little imagination, it looks like a convertible cooper!
personally I think if you go for a car which is distinctive you should go one step farther and make it yellow to really get noticed.
go for yellow.