avlady - I have been doing a lot of Catastrophic Thinking work. While my anxieties still have a hold on my life I am able to mostly function - like drive a car, be in a crowded situation, and go to large very crowded stores. even better, I can do these things spontaneously now. Still, while participating in these things I have to rely on coping skills but, excepting a few types of situations, the fear generally doesn't prevent me from crossing the barrier

My suggestion is to do some homework (CBT sites are good for worksheets on 'de-catastrophic thinking) before having to face riding in a car.