Lucid Gravity in the wild

[hmp10]

Turns out there are a number of cars that have had this feature.

Thanks for this more detailed photo:

From the earlier photo I was guessing that the locking mechanism somehow rotated into the sill slot, and I was wondering about how much mechanical complexity (and future maintenance issues) that would entail. But it looks like this "slot and hook" is quite simple and probably never comes into play unless the door is pushed inward in a collision. I'm wondering if it even allowed a reduction in the size/weight of the side impact beam in the door?