Third row seat? Isn't it the area where the energy from a rear impact would have been absorbed? And you want me to put there the most precious possession that I have and will never be able to replace? Forgive the guy who was rear-ended twice on separate occassions, once in '95 and the other time in '98 - I am still looking with paranoia in the mirror everytime I am the last guy at a traffic light!!!
On the other hand, maybe the BMW guys have come up with an acceptable solution for the energy absorbtion - folks, please enlighten me...