For ideas, try looking at webshots racecars and see what is going on around the country in the different divisions and use some of the layout styles that fit the colors you will be dealing with. I wouldn't rip off the whole layout exactly, just take a little from a few.
For clipart, I guess anything checkered flags and flames would be a good start. And some "swoopy" stripe kits would also be good.
Most all of the racers I have dealt with are more interested in the colors I will use than the stripes.