Whenever you knowingly loan your car to a friend, family member, co-worker etc, you may be covered under your automobile insurance policy. In fact, even if you do not give explicit permission each time a person borrows your car, you may be covered as long as they had a reasonable belief that you would have given them permission to drive the car. If you are carrying a named-operator policy, only the individuals named on the policy are covered while they drive your car. Although often less expensive, a named operator policy should be clearly disclosed before you purchase the policy.
Also, you should be aware that when you purchase liability insurance, that coverage goes with you from car to car. (This is not true in all cases read your policy) In other words, if you borrow a friend’s car and are involved in an accident, and have car to car coverage, your liability policy will cover you when driving your friend’s car. However your liability policy will not protect your friend, he/she must have their own liability insurance to be protected. Conversely, it is important to make sure that the people who drive your car have insurance. Because irregardless of whether or not they have insurance, you can still be sued. Very important to understand is that under California law the registered owner of the vehicle is the one responsible for the damage caused by their vehicle, even if they are not driving it (except in the case of stolen cars). So if your friend is driving your car not only will your friend get sued but so will you.