If you lend your vehicle to a friend and that friend gets into a car accident, whether or not you will have to pay the bill is going to be based on your state law, your insurance policy, and the circumstances surrounding the accident. In many cases, when you lend someone else your vehicle, your insurance will cover any accident that occurs when that person was driving. However, in these cases, your insurance will only cover the car accident if the person took your vehicle with your permission and if it was reasonable of you to grant that permission.
If it is considered negligent for you to have loaned your vehicle to your friend, your insurer may refuse to assume any responsibility for paying the bills--this is known as owner's negligence. For example, if your friend had no driver's license and you gave her your car anyway, or if your friend was under the influence of alcohol and you knew that when you handed her the keys, your insurance company is likely to deny coverage.
Even in instances where it was reasonable to lend a car to a friend, not every insurance policy will cover every situation where an accident happens. You should review the terms of your policy to determine exactly what type of coverage you have on your vehicle and whether it will extend to third party drivers. In addition, if you intend to have someone else drive your vehicle on a regular basis, it is a good idea to get that person added to your insurance policy.
Special situations may also arise if you live in one of the twelve states that operates under "no fault rules." In these states, each licensed driver is generally required to make any car accident claims for injuries that are suffered through his or her own personal injury (PIP) coverage. This coverage is the exclusive remedy unless the injuries are defined as "serious." As such, you should not face responsibility in one of these states except in rare instances where injuries occur that are severe, expensive to treat, or permanent.
Your responsibility for loaning your car to a friend is a complicated question and there is no one answer to whether you'll have to pay the bills from an car accident in this situation. No matter what, though, it is important to report any accidents involving your car to your insurance company, whether you were driving or not. You should also contact an auto accident attorney for more specific advice if you find yourself dealing with a situation where your responsibility for a negligent friend is uncertain.