I've been having this wierd dream ever since i was 4 (i'm almost 13 now). It's really freakin me out.?

I've been dreaming about me in a car rolling down a hill, alone. I'm always in the back seat and the seatbelt is jammed. It always starts when somebody leaves the car. It always happens in different settings, if that helps. The dream always ends right after I crash into a mountain or wall. Could somebody please explain what the heck is happening?! Thx in advance.