I will add that not having a car in Boston seems more realistic day-to-day,) but once you start with your externships you'll kick yourself if you do not have a car...you'll need to find another way to get there- Uber, public transit (could be 2+hrs each way depending), zipcar...which could be way more expensive & time consuming. My advice: no car year 1, defintely have access to a car year 2.
I think it's also important to remember that no placements are guaranteed, so don't go to one program only because you expect a placement at a particular institution. You should go for the whole educational package.