There’s no saying what will create zombies or by what rules. in I am Legend the zombies weren’t re-animated dead, they were humans infected by a faulty medication that cause mutations, in the Walking Dead the mobility of the dead depends on how far along the decomposing process is. Thats what makes zombies the last horrific threat. We can only guess but we’ll only know for sure in time. The only tip I’d make to everyone is to not be so attached to things requiring gasoline.
Thanks for the zombie tip.