My dog got hit by a car. Will she remember and
avoid cars in the future?

I couldn't resist answering your question about a repeat performance. I signed a large breed dog for training many years ago. Just before her first lesson she broke her right leg while jumping off a second floor balcony to visit with the kids coming home from school down below.

 

OK. So three months later we scheduled her for that first lesson again. Unbelievably she jumped off the same balcony for the same reason and broke the other leg! Don't count on your dog to learn that lesson just because of a painful and debilitating injury. Do whatever necessary to deny access to the area.