Smokey Yunick once went to Daytona with a Chevelle, with the fenders covering the rear wheels. It gave him quite an aerodynamic advantage, but was going to make tire changing during the race a real problem.
Other owners complained, but Smokey pointed out that the rulebook said he could cut out the fenders if he wanted to, and he said that he didn't want to.
He ran with it, and the car qualified very high. As soon as the car qualified, he rolled it into the paddock, and started cutting metal from around the wheels.
Other owners complained.
Smokey pointed out that the rule books said he could cut them out, but didn't say when he had to.......
I belive it was the 67 or 68 Daytona 500 when Smokey Yunick entered a perfect 7/8ths scale Chevelle.
The car was lowered to the point that the tires were tucked up inside the wheel wells almost rubbing the sheet metal. The other teams ran with large cut-outs to clear the tires.
The teams all protested and NASCAR said there was nothing in the rule books saying the tires couldn't be tucked inside the fenders.
Smokeys car went out and easily won poll position. No other team could beat it during qualifying.
Prior to start of the race Smokey took a sawzall and cut the wheel openings to clear all the tires.
Again the other teams protested.
NASCAR said there's nothing in the rules that say he can't do that.
It was because of Smokeys 7/8ths Chevelle that NASCAR now uses templates to check body size and shape and wheel openings.