I don't want to share my car
Why don't you want to share?
I want to be the only one in possession of it right now.
It's understandable to want to have something you can call your own, but its selfish not to share with others. Others may end up treating you the same in return.
I'm really selfish, huh?
It's a good thing you recognize that, and you can only take steps to fix that! Sharing is caring, and I'm sure your family would be grateful to be able to use your car in emergencies.