Hi! I'm very sorry to hear about your Mom. It's tough losing a parent regardless of how old you are. Your Dad just lost someone who was very special to him and maybe he's afraid of losing you too. Maybe he doesn't realize that by tightening the reins on you he's not protecting you, he's pushing you away. It might help to talk with your minister, school counselor, a trusted teacher, or an adult relative you're especially close to. You're obviously in a whole lot of pain right now and my instincts tell me there are other issues going on. You do need to talk to a RESPONSIBLE ADULT about all the things that are messing up your head. The passing of your Mom is still very new and this is no time for your family to fall apart like this. This is a very difficult time for all of you. I get the sense that a sit down with your Dad isn't an option for you. Please talk to someone asap!
I guess the next question is, have you ever given your Dad a reason not to trust you? You don't have to tell any of us, just answer honestly to your own self. That could certainly be part of the problem. At 18 we think we're grown and can accomplish anything we want. In a sense that's true, I felt that way when I was 18. But you're just starting out in a world that can be wonderful yet at the same time rather cruel. There's plenty of time, don't rush into anything. As for the car, you can call your state Division of Motor Vehicles to find out how old you have to be for the title to be in your name. That's a matter of public record.
Please,please,please don't make any hasty decisions right now. Talk to someone right away so hopefully there will be no regrets down the road.....