White always wins in sales, due to all the commercial and fleet sales. So it sort of skews the results. Red is always pretty high too. Silver, gray, gold, that awful unflattering "greige" that so many Toyotas and Buicks are, are usually pretty high volume too. Dark green was #2 after white when I bought my dark green '93 F150, and was still pretty high when I bought a dark green '95 Golf, my sister bought a dark green '96 Jetta, and I bought a dark green '98 Jetta. But now it has all but fallen off the sales chart, so much so that hardly any greens are even available any more. Black always sells reasonably well too.
Some people do not care, even if they are buying new, since so many Americans live in a hand-to-mouth world they have the need for instant gratification. So they buy within the confines of whatever cars a dealer has on the lot. Dealers won't want to stock anything that is a little off the wall color wise. This tends to homogenize a lot of what you see on the roads as a result.
I have a Sundown Orange 2005 New Beetle. Think General Lee from the Dukes of Hazzard. It is literally like the third one of these I have EVER seen that color. I love it!
But it fits that car. The same color on a Jetta would be a bit strange.
I like some of the cool retro colors available on the Camaro, Mustang, and especially on the Challenger and 500. Fiat really has that part in the bag when it comes to the pull-me-over colors. That Grabber Green Challenger with matte black stripes and wheels is an awesome looking car to me.