If someone is in your personal vehicle hold select and go to Empty Personal Vehicle (10/13).
To throw someone out the driver seat hold triangle while outside the vehicle.
I have crew members that are not on my friends list that think its ok to just hop in my car and speed off. Sometimes i forget to switch it back from crew+friends to friends only. So i started rigging all my cars with remote bomb just if that happens, for anyone really that stole my personal car. I use to be cheap and put a stick bomb in a good spot also lol.
I recently just found out you can empty your car today, and thats a great feature.