Sandy,
We have a pack of about 30 boys in a small town of about 1500. I am the Cubmaster for our Pack and I don't get too picky with the rules. Most of the boys eventually come by my house to have their cars cut out and end up painting them there and I end up putting on the wheels. So I have not only inspected them I also help them build them. This arrangement usually works well except my son's car in not done until the day before the race because I have been busy with everyone's cars. He doesn't mind because I set aside one evening to work on his. Since we are in a small town we make the PWD a community event. We sell hot dogs and such as a fund raiser at the race. I usually have the 4 classes for the cub scouts and an open class for everyone else. I searched the internet and found a chart system that works for us low tech types. Here is the web address http://members.aol.com/standcmr/ppngen.html Overall everyone has a good time and are not that competitive. This year we had a test and tune the night before. We let the boys send their cars down the track all evening. I figured they bought the track they might as well use it. We are fairly informal and just have a good time.