They say, White is the easiest to resell.
With that said, the smart IS as much as a Niche market as one could find, there has been throughout this forum discussion on how difficult it is to pick a color, with one specific posting stating, 'it probably doesnt matter, I would be happy driving any of them.' This is so true, look at the Swatch Towers, they all look good. Then look at any other manufacturers cars, blah blah blah well that one isnt that bad of a color.
Last point, look at the colors that PAG has used for marketing the last couple months ... Blue against the tile mosaic wall..... at LA Car Show Blue,Red, and... The Brabus Racer at the smart house is Yellow. I have noted that Silver is the marketers choice for the Tridion cell.