I spent 10 months at an American university 2 years ago. I was told that whilst it would be relatively easy to buy a car (couple of hundred dollars) I would need to get a New York State drivers licence as I would be using the vehicle for an extended period. Furthermore, I was told that it would be very difficult for me to get insurance and that it would cost a fortune. In the end I ended up renting a car whenever I needed one (which was not that often because I was working like a dog). What I discovered was that if you are polite and courteous and build up a relationship with a local branch, you can get some really good deals from the rental companies. This will then give you 1) insurance, 2) a new low mileage vehicle and 3) backup (if the ashtray is full etc)