So I have a theory that the carrying capacity of a car has nothing to do with the size of the car and everything to do with how much the owner cares about the car and the comfort tolerance of the passengers. Out of all the loads I've observed carried with a car(pickups count as cars but not vans or trailers) the biggest are always in a small beat-up old car full of tolerant and poor young people. I can't think of a time when I've tried loading a car and stopped because the car is too small, it's always because the owner objects.