I've lived in the Northeast practically my whole life. Still, the whole concept of driving a car into the house just seems downright WRONG. But if you must (and you shouldn't, but if you must) there's no reason you can't just use a standard roll of vapor barrier to seal it off. Use duct tape to make it air tight. Done, and cheap. You'll poke holes in it. Big deal. Seal it with a piece of duct tape. Eventually it'll get ugly. Big deal. Tear it down and put up another sheet (you buy it by the roll. It will last you a while ).
That's where I'd start because it's cheap and simple. In the meantime, you can reconsider the whole "garage" concept before spending any money on a "real" solution.
Just my opinion.