6 Answers

Well I guess that when you blow in his face he is aware that you are playing a practical joke on him, and he finds that annoying. Looking out of the car window is exciting for him because he sees lots of new stuff and has the landscape just flying by. Maybe your pup gets some kind of kick out of that sensation of effortless speed and freedom.

Generally, it seems to me that dogs love to travel by car.

Well I would think that because sticking his head out of the window or not is his choice, but you blowing in his face is not his choice do not blame him much myself would not like it if someone blowed in my face.

They like the oders outside of the car and dislike the oder of a humans breath

hahaha, this is the same for cats.. i imagine it's because they can tell the difference. The wind of nature does not feel like the wind of a human.

Sorry just one more thing. Stand in front of a fan. now control the air flow to a narrow pipe the size of your pursed lips when you are blowing. Hurts doesn't it.

To blow in his face means you have to face him. Dogs do not like confrontation. It is an insult to them. Also whilst hanging their heads out of windows they pick up many scents. Don't take this the wrong way no insult is intended. Perhaps the dog does not like your breath. you may have the most brushed healthiest teeth on the block but dogs do not like the smell of tooth paste. Stick some on a tooth brush and watch them sneeze or back away from it.