I was watching a show called "Good Dog" by Dr. Stanley Coren. He was offering tips with these car problems. He mentioned trying to just sit in there for a couple minutes and feeding the dog, giving it treats and making it a happy place. I guess once you're sure she's comfortable in there, you could drive around the block a couple times (just make sure you didn't fill her up with food..you're bound to get it back if you know what I mean) . Then you can turn a couple blocks into a trip to the store and build up. Try to keep it a really happy place for her.