We had a player stopped because of a flat tire. While he was attempting to fix the flat for several turns, another player had stopped adjacent to him to attempt roadside repairs for a mechanical problem. While both cars were stopped adjacent to each other, one of the players siphoned gas from the other, which resulted in the car being completely empty. Since the car with no gas can't move, how is he supposed to play a move / road card to forage for gas? Is he just out of the game?
He can forage (6.72). Essentially he pushes his card out on a side road. (Entering a side roads costs no fuel.) This will certainly consume some time, but he is still in the game.
Note that every side road automatically has a rest stop on it.
He could also try to draw a "siphon gas" card, which he could use even with no player adjacent (he is just siphoning gas from a unlucky car nearby.)