Instead of restricting vehicles to carry particular items, they should give bonuses instead. F.e. Nuka Cola Van could generate Nuka Colas if you supply it with mats (small energy cells...).Maybe this will sound too off, but military vehicles (hummer?) could give bonuses on the battlefield, if present. Like those military trucks could give +5% dmg to everyone from the same faction in a certain radius around them.So all in all, vehicles should have their purpose, different vehicle for different job. Most of all, there is no need to add more vehicles, just to diversify existing ones.