Non-owners coverage is mainly to cover you with liability for what you do to others, if you get in anyones car , or a rental car , or any car you do not own. It is excess over any other collectible insurance. If no other collectible insurance then yours typlically would become primary. However, since there is no comprehensive and collision coverage for a non-owners policy, there would not be coverage for your friends vehicle. These responses are for information purposes. It should not be interpreted as a recommendation to buy or sell any insurance product, or to provide financial or legal advice. Please refer to your insurance policy for specific coverage and exclusion information.