“the cars and trucks may still work, but the electric gas pumps (on grid power) won’t.”
That is absolutely true, and we will be stuck in place when our gasoline tank is empty (got water/food) but when the grid is finally fixed, the cars and trucks won’t be dead pieces of junk and that is a big advantage.
Also, if it’s an EMP attack, hopefully, part of the US will still work and maybe there will be a refining plant in that section.
You are missing the point that it takes a heck of a lot more than restoring the grid to restoring the gasoline supply.