My little Yorkie-poo, Chipper, loves to go for rides in the car, and he always stays right on the seat, and curled up safely. I usually put the window part-way down, that way he does get some of the fresh air, but he can't accidently fall out of the window.
His favorite thing is when we go to pick up my husband from his job at the grocery store. He works in the meat department; so he always has that wonderful "chicken-y smell" that Chipper finds totally intoxicating.
All I have to do is say "time to go and get Daddy", and he is jumping up and down and ready to head out of the door.
When I had my minivan, he used to even have his own little car seat for Elmo and Chipper to sit in.
I was rading today about a man that almost drowned both himself and his dog because he had the large GS dog loose in the front seat with the leash dragging. The leash got tangled up in th shifting lever, and then the dog fell on the floor and hit the gas pedal, throwing the car right into the water, and almost drowning both of them.
The car was ruined, but both the man and his dog survived, thanks to quick help from passers-by.
So, it is very important to keep your dog in a safe place when he is riding in the car with you !