If you're caught driving an uninsured car, you may be liable for any damages or injuries that occur while you're driving. You could also be fined or have your license suspended.
To avoid any problems, it's important to make sure you have insurance for any car you drive. If you're renting a car, be sure to ask the rental company about their insurance options. If you're borrowing a friend's car, make sure they have insurance that will cover you.
If you're not sure whether or not your policy will cover you to drive an uninsured car, contact your insurance company for more information.