I figured I would throw my opinion in here. I've lived in San Diego all my life. Honestly, I think it would be darn near impossible to not have a car in this city. The public transportation is not that great, especially in north county (which is where UCSD is). I would recommend living further from campus and commuting by car. However, if you plan on being a hermit and only doing school all the time (which seems fairly likely for a grad student), then you might get away with living on campus or very near campus and not getting a car. If you are into extracurricular stuff (nightlife, surfing, shopping), I highly recommend living in one of the places ewurgler recommended (North Park and Hillcrest I LOVE), or Clairemont which is cheaper, and getting a car.