achievement rewards, aka race rewards for those who can't race

Simple idea (that I'm sure someone else must have already had, but I'll mention it just in case):

It would be nice if there was a way to acquire some of the alternate art items for those of us who don't have the right schedule to race.

The new Achievement system seems ready-made to be PERFECT for this. Some of them take forever to complete, but you can at least complete them at your own pace. Sticking some of the current/old race rewards (the low->mid tier ones) in there as rewards for casual/erratic players would be a great perk and a nice way to encourage players to attain achievements.

Thoughts?

Or, if the race rewards *must* remain unique - maybe a separate set of achievement rewards?