personally, I don't think it's a good idea. .what if the dog came up and gave you a kiss while you were driving? it's unsafe for the dog and the driver..so it's not okay in my book. It's just an accident waiting to happen..plus the dog could lose its' balance and fall out the window if it was small. not a good idea at all IMO. when my mom is driving, Ginger crawls up on my mom's lap, but we make her get down.