The only time I let my babies put their heads out the window is when I'm not driving , which is very rare, and I'm holding them. We have to be in the neighborhood or it doesn't happen. Anything can happen. My cousin lost his dog by it jumping out of the window. He was in the country visiting his parents. He was getting ready to leave, had the window down to tell them goodbye and Bubua, who was in his Daddy's lap, got excited and jumped out the window, Bubua had never tried to jump out before. His Daddy accidently ran him over. This happened three years ago and my cousin is still heartbroken. So if I don't have a firm hold on their collar they don't do it. If I'm alone with them they have the window on a small crack. If they want fresh air they can get it when we get out of the truck at home. Sorry, I may sound mean but, after Bubua I'm not taking chances with my babies. BTW, Bubua was 15 years old, his Daddy had him since he was born.