That looks pretty small for a real, curvy track. I'd just make it a lane down and a lane back with turn-arounds at the ends(so, a long oval).., and instead focus on the jumps. What would be coolest of all would be to bank the ends..

On a side-note, not that I've ever raced, but I think a BMX track would be the ideal track, with banks and BIG jumps, and not all these little snaky, bumpy, flat things I see in the vids.. That's why the whole world is going to truggies I guess..