It is a BP rule apparently but has nothing to do classic cars, but where the gas tank is located. The rule says no doors, trunks, etc can be open while filling.
I’m guessing it is a rule to help prevent theft of gas or something.
I would think that ANY residual HEAT would be the reason.
Gasoline has a low flash point.
WHAT KIND OF CAR WAS THIS???
LOVE MY 1976 1 ton Chevy truck & 1979 Buick wagon MORE EACH DAY