I used to live in Boston, and you don't really need a car to get around - the public transportation is pretty convenient. Parking can be a pain too. On the other hand, there were a few times I thought a car would be nice to have - ie: going away for the weekend, dragging arond groceries, etc.
One thing I have heard about B.U. is that there are a significant number of students from the special Seven-Year Med program and the MMEDIC program, which I think lets you in after your sophomore year. My brother went to B.U. grad school and heard from some of his friends who were at the medical school that they just could not stand those students - immature, petty and cutthroat. But he loved the school otherwise. I think B.U. has a good program, and if you can distance yourself away from the obsessed teeny-boppers, you'd love Boston - it is a great city. I hope to live there again sometime.