My baby has the GlobalPet carseat. it is a carseat, suitcase, and bed all rolled into one. It straps into your car much like a child's carseat and has a hook so that you can strap them in by their harness. It costs around $80, but worth the money. Bouncer LOVES IT. Especially since it puts him right at the window where he can don his doggles and let his hair fly when the window's down! hehe
Of course, he always rides in the backseat since the airbag just isn't safe for his tiny size if something where ever to happen and we were in a wreck.