I don't know if the touch functions would work that well on a Nano, thinking about device size vs finger size, might not be an ideal setup. Though if they go for an almost full screen on the front it would be more practical, but then you need to consider if the dimensions are ok for video playback.
As to the colors, in PGR4 for XBOX they offered a way to paint the cars where you took a pattern and then laid it over the car in any way you wanted so you could get more or less of certain parts of the pattern. Something like this could be offered for online ordering and would certainly give you a more custom/individual look as even though you share the same pattern you won't necessarily have the pattern showing in the exact same way.
Also, for a more full screen Nano, you can leave the front edges a solid color and allow freedom on the back.