Since you are competing against a clock and not another car, there's some room for interpretation there. You may have to word your claim a certain way. All I know is there are several people that I know of that have made a claim following an autocross incedent and had no problem. I'm sure it also varies from company to company. I suppose you'll need to read the fine print in your policy to know for sure.
92 SE-R from Heck
"What have you DONE to that thing..." - stranger at Rockingham dragway 5/18/01
"Where's the turbo?" - stranger at the 1st autocross of 2000 where my SE-R debuted
"That thing is a goddamn rocket ship. I'm not lifting for you on the straights anymore!" -Karl Shultz, Rockingham 4/27/01
"What in the hell have you done since I drove it last?" -David Stone, Rockingham 4/27/01