I have traveled with multiple dogs. In the past some have ridden free and some have ridden in crates some of the time. I enjoy having their company up on the passenger seat, they roll their eyes when I take the wrong exit and they tell me the most amazing stories.
But other times, I think they get more rest in the crates and I don't have to think twice about gas station/ restaurant/Campground office stops because they are in crates, safe and quiet...waiting....
I would not travel with my passenger window down....I respect the "prey drive" of dogs too much and their instinct to go after something.
Because most all of my critters have attended dog shows (performance or conformation) at some point in their life they have all learned from experience that crates are where they might as well relax and sleep 'cause no matter what those other dogs in set up next to me are doing, they may be here for a while. They often as not eat in their crate and the smaller dogs use the crates when I leave them alone in the rig. That way I know that they are not up at the front windows barking at every SQUIRREL that might chance to climb a near by tree much less barking at the folks walking their pup past the rig.... They are also used to using the crates when not traveling. Crates are just a part of their life and provide them a freedom to go more places more often.
The big Herschel dog, though he graduated from his travel kennel early in his life, he knew how to use a soft sided one if he was going to obedience class as demo dog and he had to take turns while I worked with another dog. Traveling, I always carried an emergency soft sided crate for him should I ever have needed to stay in a motel.
I think that having to provide safety and comfort to multiple dogs has allowed my to appreciate that I would always want even an individual dog to understand that a crate is a good place. Both Stuart and Remi get to ride free and spend their time either on the bed or up on the navigator's seat. When they ride in their crates I don't think that they miss it nearly as much as I miss the stories they tell me (when they are actually awake
) as they watch the roads and towns roll by.
The choices are all personal preferences based on experiences and the needs of our animals....