I think the hardest part of not having a car in LA would be that its is so counter-cultural. The assumption is that everyone drives, so of course your friends will make plans 45 minutes away without thinking about public transportation options. Public transport in LA is better than it once was and depending on the university, for day to day life and where you live, you can probably get away with it. Part of LA's over-dependence on cars is that most people live really far from where they work because of housing costs or being wealthy enough to live in the beach cities and work downtown/Hollywood. I would say if your housing works out go for it, but expect everyone in LA to think you are crazy.