I have a 17 mo. female German Shepherd Dog. She is solid black, beautiful and so loving. My difficulty is that she barks in the car at pedestrians and even passing cars. I have finally gotten her to stop barking with "enough!", as I want her to stop after I acknowledge her protective alert. This does not work in the car, nor does it work if she is on leash. Off leash, she loves on other dogs. Suggestions? Thx!