You are Lord Humongous: Design Your Death MobileS

Yeah, we'll stick with movie themes, why not? Today's Question comes from none other than... Tocsin? Sure, Tocsin. Here's what he asks:

The year is 2013 and civilization as we know it is dead, you've got a
mild bit of radiation poisoning from wandering the wastelands and
beating off packs of mutant wild dogs with a tyre-iron, your
fingertips are scabbed, you've got lots of imagination, limited
resources and the auto mobile of your post-apocalyptic choice. Now,
how are you going to modify said auto so that you'll have some proper
credibility with all the other wasteland bandits? (And remember,
you're probably going to have to do battle against a road-train tanker
with a bloke in a leather jacket driving it to get yourself some
petrol, so this thing has to be fighting fit too.) Right. Lord Humongous, design thy death-mobile!
For the record, we love this Question. And Vernon Wells is God. Now, go!