If I recall correctly, collision testing is only done between vehicles of equivalent size. I do not for the life of me know why that is, but it's a pretty big problem for the safety standards.
This thinking makes US keep moving towards driving literal tanks on the road.
It would be great if we could end this arms race of bigger and bigger cars - they're less efficient, worse for pedestrians (bad sight lines and likeliness of injury if hit), take up more space and most of all - completely unnecessary in most cases!