The gas thing we may just have to handwave and ignore until/unless it's specifically addressed in the show that viable fuel is becoming more and more scarce. One advantage with diesel engines is that they can run on vegetable oil. Granted, doing it on straight oil has a number of problems and cars that do it today need some modifications to do it efficiently and to not clog or damage the engine but when you can just go grab another car in the ZA this wouldn't be *too* much of a problem.
I was envisioning that they could make bio-diesel from the vegetable oil and the turpentine that forms from old gasoline. Apparently those are the ingredients. But I read around and it appears that old gas doesn't literally turn to turpentine. I guess that's a misunderstanding. I'm not clear what it does turn into and whether it could still be used as fuel in some way.
Still, if we just envisioned that scouting parties made a point of either carrying or scavenging a gallon of vegetable oil, that would explain how a car could reliably run with supposedly old fuel when picked up off the street. Just make sure it's a diesel, dump your oil in the tank, and go. (Maybe drain the old stuff out of the tank first.
