One of the most common questions we hear is, "If I lend my car to someone, are they covered (by insurance)?"
Remember this phrase, and you will always know the answer to that questions: Lend your car, you lend your car insurance.
One exception to this rule (there's always exceptions to every rule, right?) is when someone lives in the same household as you. The reason for this is because, people that live in the same household as you have access to your car. And insurance companies have gotten smart and written the car insurance policies such that people living in your household must be added to your policy or deleted. If it is determined that the person lives with you but was not added to your policy, you are usually inviting coverage problems with your insurance company. (Ask your insurance company or your licensed insurance agent about "permissive use" drivers to find out what your coverage is.)
Also ask yourself, "are my limits and coverages adequate?" Often times, this question does not get addressed until after there has been an accident.
Review your car insurance policy annually. Don't wait until you buy a new car, like most people do.