Floating Wingmirrors?

Why do vehicle wingmirrors seem to stay in the same place when the vehicle is deformed? I've literally only just noticed this.

I know that dynamic props like dials and pedals seem to have a weird central axis underneath the car so they don't move when hit, but I didn't think this was true for mirrors, I assumed they were part of the door or body.
Is this an actual bug or a known issue? I couldn't seem to find anything about it.

 

This is a problem with the geometry of the physics skeleton on the Moonhawk specifically. The way the Moonhawk's mirrors are attached, they can "pop out" much like the indented lids on vacuum sealed cans do when the car receives enough force. It also causes the doors to go all wibbly until the mirror falls off completely.

Take the Moonhawk off a jump just big enough for it to bottom out and watch the landing in slow mo. You'll notice the mirrors jump away from the door very quickly.

 

Oh I see. I managed to get it to happen with the mirror on the covet door as well, though it wasn't as noticeable.