Adult son constantly using my car

My adult son has no job right now and is living at home with us. He has no car and constantly uses my car. Before he had a part time job and I had no problem letting him use my car for that and for any other necessary errands, but when he used it for any other thing like running errands for his girlfriend and driving her to the bus station which is an hour away from where we live that’s when I get irritated. Also, when he let his friends ride in my car. I got irritated because they left the car so dirty with greasy hand marks all over the place and the mat so dirty. I told him so many times to take care of my car the way I took care of it because that will be my retirement car, but he is still not doing so. Recently, my car got into accident with him and his brother driving and I had to bring it to the repair shop. Now that my car is out of the repair shop, I really want to be very strict about it. How do I convey to him all of this without sounding so judgmental or accusing and still maintain good relationship with him? I only want my car used for important errands and not for driving other people around. Please help me what to say.