If you take your dog with you everywhere you go, you probably take a lot of safety precautions. He probably wears a harness, and I’m sure you bring a leash with you wherever you go. There are also some precautions that you should take when bringing your pet along for a car ride.
If your dog is free to roam around the vehicle while driving, it will be dangerous for you, him and any other passengers in the vehicle. A free roaming dog will distract you, and he will become a dangerous projectile in the event of an accident. He could also climb into your lap, get into things that he shouldn’t, or any number of other distracting behaviors.