A nice shot. I would have chosen a different angle to photo the car, to get better lighting - with all the light falling on the far side of the car, the image looks quite flat. I think I'd have cropped it a little tighter as well - still kep the strong horizontal line elements, but tightened it up just a little.
It's a nice shot. Composed well, exposed correctly, etc... Bit of a clich'e perhaps when one thinks of a motion blur shot. Hope you had fun at the event. Best of luck in the challenge.
Crop right down there - all that blur isn't really adding to the photo IMO - maybe an angled crop to break up all those horizontal lines? Having tried to shoot these cars I appreciate how difficult this actually is - it's really nice work.