At the beginning, Sally has curly long blond hair, and its very neat and nice, but when they go to the diner it is sloppy and not as nice, as anyones hair would be who had just been riding in the car for about 6 hours. However, when they leave the diner and get back on the road, her hair magically is nice and neat again, and there is no way she could have fixed it, because she didn't have a curling iron. Even if she did, she was driving and anyone who has curled their hair, knows you can't drive at the same time.