The Evacuation idea can explain a lot, assuming it went roughly like this:
People left in panic, vaguely organised by the military, so that although vast portions of the population were already zombified, many others left the cities in cars, packing them full to the brim with food and supplies which were deliberately handed out to civilians in the hopes that they’d show up at refugee camps and be redistributed there. Because the cars were packed so full, it was often one civilian per car, which meant that a lot of vehicles were used by relatively few people. Special personnel stayed behind for as long as possible before being evacuated (e.g. scientists and military).
This explains:
Lack of parked vehicles
Lack of food
Lack of other supplies
Lack of survivors
The random groups of dead soldiers and scientists where there are no dead civilians
I don’t think I like gtaguy’s idea of unreliable equipment. That takes control out of the player’s hand. Instead can’t we make it so that there are plenty of vehicle parts and vehicles lying around, but the limiting factors are:
Technical ability (i.e. A new character can’t just make a deathmobile. It takes a month or two to reach that skill, and significant dedication to training!)
Fuel (Seriously. This needs to be a limiting factor asap, otherwise vehicles will remain OP!)
