It really does depend, if it's a classic, then it should be red or yellow. The more modern ones seem to look just as good in monotone colors as vibrant colors.
My personal favorite, the 550 Maranello, looks best in a metallic gray or black imo.
I would prefer having some form of power and weight control, so what the dev's could do is make the slider that controls the power limit go up as well as down,that goes for weight as well. It'd provide more freedom of choice, without the nfs style modification.
Either that, or they could add a tweak like application to the game for off line use in the latest patches.
But realistically, the only add-on I think could be used, and should be implemented is an "official" wheel modifier, like be-spoke. Because imo, the wheels on the Xrt are ghastly.
edit: It was my great great great great grandfather who flew the fist airmail cross country, but crashed after leaving Regina. There is even a monument made out of the wreckage in Saskatchewan.
-I was on the news at 11 wishing a Canucks player good luck with his injury...
-My great grandfather flew airmail over the rockies in the 1930`s and was in a newspaper...
-I was on the news again because I had to be evac`d from my apartment, drug lab found on 9th floor...
Haha, I found two San Pellegrino bottles from the 1910`s in a warehouse my dad and I are restoring, we don`t know how much they are worth either. Best of luck with the chairs though!