[dsfyu404ed]

Contrast the good results of the overlap tests with the report (posted on HN awhile back) from the Tesla that rear-ended the corner of a firetruck at ~35mph that had substantial firewall deformation.

It's worth remembering that modern cars are very highly optimized for the tests they have to pass. I'm not saying the M3 or any specific car is good or bad, just take the results with a grain of salt because these metrics are very much targets.

[dlivingston]

I don't think the deformation of that crash is what was relevant; rather, it appears that autopilot failed to act correctly in that situation.

In terms of the "firewall deformation", from what I understand this is exactly what is supposed to happen in a collision: there is a "crumple zone" [0] in modern cars as a safety feature to absorb impact.

[0]: https://en.wikipedia.org/wiki/Crumple_zone

[dsfyu404ed]

The firewall is the edge of the passenger cabin. There should be no crumpling going on because the perimeter of it is the structural component that ties together the A-pillars and rocker panel structure. If you crumple the firwall you are pushing the dash structure back at the occupants and removing support from the A-pillars allowing them to more easily deform. Getting it to deform 6" or so (I recall that was the number they stated, I'd need to check to be sure though) in a crash that was well within the range of speeds vehicles are crash tested at is noteworthy.

Edit: Is the firewall is structurally irrelevant in modern cars or is reality not convenient today? The inability for people to disagree without trying to silence each other is why people complain that HN is turning into Reddit.

[FireBeyond]

Firefighter / Paramedic here: when we get firewall impingement, we get dash impingement, which can easily result in us having to "roll" the dash up/off an occupant to unpin them with our rescue tools. Modern cars shouldn't impinge the firewall unless many things have gone wrong.