I just read the article in the new Motor Trend about how racers used all the advantages possible that the rules didn't quite specify to get an edge. I thought it would be cool to put together a thread with as many loop-holes used in racing we could conjur up. Here's a few from that article that stood out and then some:
(I'm not sure I have all the names right, I left the mag at school)
*Smokey Yunick was the first to test with nitrous after his dentist told him that laughing gas contained more oxygen than regular air
*In the earlier days NASCAR Darrel Waltrip's crew would fill the frame rails with lead shot, then release it during caution laps with a valve on the floor with a wrench from inside the car, because the officals only weighed the cars in before the race
*NASCAR rules specified that cars had 22 gallon fuel tanks, so crew would make extremly long fuel lines, adding up to 6 more gallons of fuel
*To lighten the weight of a car, crew once used wooden rollcages painted like steel
add some more!