Can't fly out while you have a vehicle in Mexico?? True?

I have no real knowledge of the rules but we know people who go down early and then fly back for holidays each year. Sue had to fly back to US doctor last year from Guadalajara with no questions asked - she had to surrender her visa (FMM) and get a new one - I stayed and the vehicles are in my name so maybe no reason to question her about that. I am betting Pete gave the best info on who to check with.