If you want it to stay small then cap the year. Otherwise open it up to anything with wheels with a 80s onwards must be modified. Get a burnout pad if you can and charge a fiver or ten bucks to go on it. Crowd pleaser that will be solid booked if you yanks are anything like us kiwis. Judging depends on how many prizes you want. Some ideas maybe... Peoples choice set at a $1 a vote, participants choice, best car in show, best bike, best 1900-1949, best 50s, best muscle car, best truck, best import, best paint, best engine bay, best burnout, best sound system, best interior, then spot prizes through out the day (great way to drop your sponsors names) If you do a best dressed/fashion show dont forget to add a wearable parts show. if you want to draw younger kids then try to get a drift team or some such to come and show the cars, answer questions and scribble there name. Even better if your burn out pad is large enough for them to do donuts or something. Really draws the younger guys all wanting to be the next drift king fast n furious style.