As an undergraduate, I did not feel I needed a car for most of my time in Berkeley. However, in my last year I did think that having a car would have broadened my experiences a bit. There are lots of interesting things to do and places to visit in the Bay Area, and having a car makes it that much easier for you to experience those things. For example, if you're an outdoorsy kind of person, it would be difficult to reach the great hiking areas in NorCal without a car. If you enjoy exploring different restaurants, having a car will reduce the headache of constantly planning for the pitfalls of public transit (frequency and transfers, mostly) when going to a new place. You may also feel safer if you drive and can avoid longer walks to/from BART stations and bus stops at night.
Though it is *much* more feasible to get around with just public transit in Berkeley than in other places, the convenience of a car is still something to consider. However, you should keep in mind that:
-it will cost you extra (can go up to ~$100/mo for covered spaces, though it can also be as low as ~$60; another option is to get a parking permit for your neighborhood and park on the streets...I want to say it's $30/yr, but don't hold me on that)
-parking will be difficult and/or expensive at times
-bridges = fees
-gas is expensive-ish there
-there is a risk your car will get broken into (it happens more than I'd like to admit, but it's just a risk you learn to live with)
Also, though I can't say for sure because I never tried to rent a studio, I'm a bit doubtful that you will be able to find a decent studio in the area for $700 - and if you do, you would most likely have to pay for water, heat, electricity, and trash! Just based on other friends' experiences, I would imagine $900-1100 is a good working range. Though at $1100, you better be blown away by the place!