Wow, I came in at a bad time...I'll put my two cents in anyway. I think it depends on climate and how long you are going to be. I've left Roscoe in the car on a few occasions while I ran into the gas station to get a coffee, but I can pretty much see him the whole time. I do think it's bad to leave the window down the whole way, my neighbor told me her dog jumped out the window at a store and ran away