If you go to UCSD I suggest you request for on-campus housing at least for the first year. It costs higher but you may not have some headache later. You will have more time to study. You cannot count on your friend as a long time roommate. You friend may split in the middle of the school year because of the following: illness, probation, not wanting to live with you anymore. You can bring your car to UCSD but you may not need it during the first year. You can easily go back and forth between UCSD and Irvine by Amtrak instead of having a car on campus.