S. and I were discussing why most cars are such boring colors. She pointed out that most people buy cars off the lot, and thus most cars will be a muted color that offends few.
My theory was that buyers worry about resale - a car with a distinctive color will be hard to sell on. This is not a very good explanation at face value; I doubt that most people think about resale when they're buying a vehicle. On the other hand, since most cars are leased, the lessors - the dealers - do worry about this. This brings us back to S.'s explanation, since they (and the manufacturers) determine the specs for the cars on the lot.
One implication of S.'s theory is that we'll see more diverse colors as more people buy cars online, or otherwise specify precisely what they want rather than buy on impulse. The color of one's car is a great way to express individuality. One can already see that cars sold in this way, like the new Bug and Mini, have much more interesting colors than the muted livery of most other marques.