Off topic: In the first crash test video in the article [0], does the rear seat completely detach from the car?? And that was a car that after NHTSA crash-testing ... basically received a perfect score . It's always amazing to me to see how much energy is involved in a car crash... it's easy to forget how dangerous cars can be.

[0] http://youtu.be/R_PnnrAtRuk?t=54

Doesn't pass the sniff test. The car may have allot of battery mass, but those rear taillights are still thin plastic and they didn't even break.

Something wrong here

If the other car was under heavy braking, it's front-end dips down and instead of a bumper-to-bumper collision, you have the rear-ending car go "under" the back of the front car.

Source: My old '81 Mustang got rear-ended at fairly high speed by a Civic and had no taillight damage. Lost my tailpipe but that was about all.