Is this a fear of cars? How can I treat it?

It would be best if you talk to a doctor and consult a psychiatrist and try to find a way to loosen up and decrease your high level of anxiety, and stop worrying and letting your fear get the best of you, you're missing out on the potential best moments of your life and its all because of this made up fear of being in a car crash. So just calm down and talk to a few specialist, the more you make up these false and terrifying scenarios the more you hurt yourself and mess up your life story in the long run.