I agree, more cars sounds good, I would prefer gathering the parts of the car you need like wheels or parts from other cars too instead from factories, same for the fuel, you should be able to take gasoline out from a car fuel tank using some kind of plastic tube and refill your empty cans until the car gasoline depletes; that would add random spots for fuel also, some cars will have more fuel than others or none at all. When one car fuel tank is depleted, it could spawn randomly in another car, same if someone take a motor part from a car it could respawn in another random car around the world.