Saw a post about you trying to 4x4 without your dog running from window to window. Check out http://sleepypod.com/clickit-sport . Shes just over a year, 40 lbs and hyper. It uses the seat belt & she can still sit up or lay down as she chooses but she can't walk around. Did a fair amount of research and this one proved to be the best from reading and watching videos on it. Only one to earn a passing crash test rating.