Since Miata isn't the answer to "Car to use during a Zombie Apocalypse" Which car, to you, is?
I think I'd take the Zombieland approach and find myself a nice GM SUV. Probably a 2500 Suburban with the 8.1L Vortec.
Who give a shit about fuel efficiency when you've got the world's supply of gas at your hand? Just have someone watch your back while pumping.
Room for 7 or 8 of your closest friends who survived and weapons.
High enough to actually get somewhere off road if needed, and to drive over piles of the dead undead.
Slap a snow plow on front Tallahassee style and move anything out of the way with all that torque from that 8.1L V8.
Reliable enough to go miles and miles without issue, which is good when all the mechanics and everyone around you wants to make you a human happy meal.
And the inside is nice enough to give you a little bit of comfort in the ruined outside world.
So, what's your idea zombie apocalypse vehicle?