If a friend borrows a car and doesn't return it how do you get it back?

Well call your friend up and ask for it back because its obviously yours and its not right to take something and not give it back. If they don't give it back then go over to their house and tell them that its your car and you want it back. If they still don't give it back by now then their not a true friend. Tell a parent or an adult and see if they can help.

Or if you have a spare key, just go get it.