I am guessing what they mean is: one can use a car as a sort of tent to spend the nights in.

If its cold and wet, I would probably just stay inside the car (provided the car has intact windows and is habitable). Why build a shelter when there is a perfectly good one already?
Now if the car was somehow damaged, turned upside down, etc, then I would probably use parts of car to build an expedient shelter and use things like wires for ropes, insulation from car seats for warmth, gasoline for firestarting and perhaps even a battery to provide light.
I have seen Les Stroud do just that with parts of an airplane when he "crashed" in Canadian winter forest.