Sorry, I misread "On Firefox the car sproings out of the clamp all the way over the exit!".
It has always sproinged just short of the exit and then rough-ridden the last bit. It still does.
windows chrome: sproings just short of the exit and then rough-riddes the last bit
windows firefox : sproings short and upside down: fails
fedora firefox: not tried, but last time I did I think it agreed with your linux firefox.