Nope, don't do it.. and thankfully I don't see very many people who do. I think it's one of the dumbest things you can do while driving. The dog can get killed if you get in an accident, get something blown into its eye, move the steering wheel, move the shifter, or if it's small enough, it can hop onto the floor and get in the way of the accelerator and/or brake pedal. I don't see why people can't leave their dog in the back (or ideally, a crate) while they're driving.. is it so hard to do?