One thing to keep in mind with cars is that parking is highly regulated in Cambridge. If you are a resident (which means that your car is registered to your address in Cambridge) you can apply for a permit and have a sticker which enables you to park in the streets all around within your zip code (very convenient!). However, this option is often not available to students living in dorms.
If you just rent or are not a resident, prepare to either rent a parking lot (Harvard Sq garage parking may serve as a temporary, though pricey, solution), get a public one which you have to add quarters every two hours, or get a guest parking permit from a resident (unfortunately, they are limited to one per year per household, and valued up to 1000USD on the black market). When you do park, make sure you read the signs: on each street there is cleaning once per month (different sides on different dates) and if you park there when it is scheduled, you’ll get towed (same for snow emergencies).