I actually have a Snoozer Look Out Booster for "each" one of my three girls.
I bought the small size and was able to fit all three in my back seat comfortably.
The girls also like having their own individual seats...just like human kids do...lol!
PS...Best of all, Car sickness ended the day we got these seats, too! So, being stable, elevated and able to see out of the window really did work for the barfin' doggies!