Funniest story I heard about that "rogue of the rules", Tom Walkinshaw. One of the team drivers brought his Group C Jaguar XJR into the pits at the end of pre race qualifying at Le mans in 1987. Rival teams had been monitoring how many laps the car seemed to be able to do on a (rules controlled) tank of fuel. Before the qualifying session, Tom had told his drivers that when they finished their sessions, that they must press THE button that had appeared, unlabelled, behind the race seat. He didn't tell them what THE button was for.

Tom: "Did you press THE button?"
Driver, getting out of the car: "You mean 'THE' button that you told me about?"
Tom: "Yes, I do mean THAT f****** button, did you press it or not?"
Driver (knowing exactly what Tom meant, and having no idea what THE button did, but winding Tom up anyway: "Yes, Tom, I did press the button, twice to make sure."
Tom: "Twice? Why bloody twice? I said once." Tom presses his head into the car and fiddles about behind the race seat.

What we were told (but we were all slightly worse for wear at the time) was that Tom had fitted a small electric pump and ram that squashed into the bag tank and reduced its apparent volume in case there was a formal objection to the scrutineers about the possible size of the tanks.

All rumour of course....