I think what you need is to promote this show 3 to 4 months ahead, but make sure check out what other event is in the area before you do one. Play different music other than cursing rap, like trance music and so on. This way the older folks and the little kids can appreicate it. Don't have the car show last till 12 midnight, maybe like a 5 till 10 show. Maybe more free giveaways, get the crowd involve while doing it. You need a better food stand with different variety food. Another thing, better weather, but you can't control that. hehe!!