It is definitely not necessary to have a car in the San Francisco Bay Area. Check out the local public transit options(link is external), such as AC Transit(link is external), BART(link is external), MUNI(link is external), and Amtrak(link is external). The Bay Area also offers ride-sharing services such as Lyft(link is external) or Uber(link is external). There are so many options in the Bay Area to get around without having to use a car. Many students also decide to purchase bicycles during their time in Berkeley.
If you decide to invest in a bike, please remember to be careful and lock your bike up at all times, as bike theft is common in Berkeley.
In addition, depending on where your housing is during the summer term, all of your classes will be walking distance. Many students also decide to not invest in any car, bike, or other means of transportation and go on foot!