Onsted Show Nationals at MIS. You can drive on the track for a $5 donation, or free if you're with certain clubs who are recognized by the show committee. I went last year, it was a blast. If there were less than 700 cars I'd be surprised. Pancake breakfast w/sausage and other stuff, too.
That's a cool happening. Live music, cars, vendors, food, etc. That on top of all the other businesses down there, you can really make a day out of it without being restricted to one field.