beautiful baby! I have a lhatese!Guess it depends on how big your dog is. My Lily is about 13lbs lol. She rides in the back seat in her own car seat/bed (got from Quadratrec). She is harnessed at all times as you can see in the pics, and the harness is connected to a seat belt tether that is locked into the seat belt receiver in the Jeep. I do give her access to the window to stand up and what not. This has seemed to work for us for years now. My girl is big on having "her place" in each of our cars. She is now trained to where it doesn't matter whos car it is, she will go sit behind the drivers seat and do what we call "paws up" which simply means she sits up so I can put her legs in the harness. Or she sits on the bumper...lol j/k.
I can't speak too much in regards to large dogs, but my mom has a standard poodle (about 60lbs) and she is harnessed as well only hers fastens to the seat belt like a human would wear it allowing her to sit up and move.