Colleen, what kind of harness is that on Sophie? I normally really don't like the seat belt harnesses because the dogs can't stand wearing them, but that one looks comfortable.
For trips into town (I'm the passenger, fyi, as I don't drive) Eve is on my lap or on the floor by my feet. Dakota is in the far back of the SUV. Ripley is in his soft-sided Sherpa bag or in my lap if I am Eve-less. For longer trips, Dakota is crated, Ripley is still in his sherpa bag and Eve is with me.
We are going to be making a 4-day driving trip in a few months with four dogs. Ripley and Dakota are old hats at this, they know to settle down and be good boys, but it should be really interesting with Eve and baby Dawn.