I suspect that with cars pretty much all of the fuel in the tank is technically usable, while most AC have a fair amount of unusable fuel in them due to the shape constraints. What that means is that to drain a car tank dry, you will also suck any dirt from the bottom of the tank through the system, with an aircraft there is space for the dirt to settle where it wont be sucked in.
No experience with this - so take this guess with a pinch of salt!