Dogs like to stick their heads out of the windows of moving cars as they can pick up very interesting scents. However if a dog sees something that s/he can't resist, the dog will jump out of the window. It's very unsafe as they don't know the dangers when jumping out - getting hit by another car, breaking bones, getting lost and so on. If you are traveling by car with your dog, make sure s/he is restrained with a doggie seatbelt and keep the window open just enough for the dog's snout to be able to smell the outdoors.
