I tried this once, but the course was so rough that I just couldn't stand to put my baby through it.  After two of my six runs, I packed it in and went home.  But when I say the course was rough, I really mean it!  Several cars blew the bead on tires, one flipped and rolled, numerous mechanical failures, etc.  Might have well been doing a crash derby.
I'd like to try it again sometime, but only on a good course, and maybe with a "disposable" car. 
 
Glad you had a good time with it...
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