Have you all seen what DUPLI_COLOR has out now.
Check this THREAD out.
Might be an idea for the weekend racer or ricer.
Kind of reminds me of that Countach in the Cannon Ball Run movie.
Just wash the color off.
Red one day Black the next.

 

This would work great for putting numbers on your car for a track/race/autocross weekend. When your done, just wash them off.

 

I read a post by a guy who did just that. He said it wasn't that easy to get the numbers right (using a stencil) and it used a lot of paint. With the amount of paint you'd need to use after just a couple events, it's simpler and cheaper to just buy magnetic numbers.