Considering all I have read on this great thread I too believe there is very little chance of ignition at the pumps. Consider that the fumes are heavier than air and will lay at the bottom of a chamber, a boat bilge, for instance. If left with no room to escape, or a bilge blower, to blow them out into the atmosphere, they pose a significant threat and will easily combust if ignited. That's why inboard marine gas engines are required to have blowers to reduce this significant hazard. The nature of cars obviously does not require a blower so unless our line leaks fumes into the trunk we are probably pretty safe. I also leave the engine running frequently at the pump, especially if I started the engine only a few minutes earlier on a cold morning.