This is where a hybrid powertrain / PHEV is superior to EV. In an ideal system you want redundancies, especially redundancies that cover for each other's weaknesses.
I think GP was referring more to aspects of a zombie apocalypse like servers being shutdown or power grid not working. Things that can happen for relatively short periods today.
I can't see a situation in an apocalypse where gasoline isn't consumed immediately, and then rationed to only government authorities. My bet would be 100% EV, and if you want redundancy, buy a generator capable of outputting to an inverter that charges the EV (then stockpile a reasonable amount of fuel for the generator).