The pre-reg levels are on the low side now, but I'm expecting it to be at least 40 cars (many people don't prereg). They cap the event off at 60 cars. Last two events I went to were full, despite low pre-regs.I couldn't get into the BMW event ... So I think I'm going to come watch whats the turnout look like? JW...
Anyways, I spoke to the organizer of the event and turns out that if you just want to try an autocross event, the first time around you can run w/o a club membership, just show up and pay the $40 "other club member" price.
So you're welcome to come watch, but I strongly suggest you give it a shot and actually participate. They have loaner helmets, so just show up, bring $40 (and make sure you can be there for the day).