What works well these days with modern cars? The need would be to access the gasoline in the cars to feed a generator during a prolonged emergency when the other storage is empty.

I bought a low cost 12v electric fuel transfer pump from harbor freight and use it to transfer diesel fuel from my Motorhome to my Kubota tractor, works great and has, for several years now.

Forget about sticking a hose down the fill tube and thinking it will make it to the tank.

The current method is to disconnect the fuel line, attach a fuel line the disconnected one, run that line into a gas can, and bypass the vehicle's fuel pump relay to use the vehicle's pump to transfer gas from the tank to the can.