I wouldn't let them drive off in my car without being passenger at least. Infact, I would probably offer to drive him, as thats how pedantic I am. I have only been to the pits 4 times, so I'm not full bottle on the whole system, but they never drove my car anywhere those 4 times. What defect do you need to be yellow stickered for to get them to take the car for a spin? I've been to Welshpool once, Warwick once, and East Perth twice and no one there ever took my car anywhere.

Good Luck Tino