If you hit an immovable object at speed in anything, you are fked, although some vehicles provide extraordinary crash protection. The only person wearing a seatbelt in the Princess Diana crash survived, and that was 80+ mph into a cement bulkhead with no deflection whatsoever.
I saw this *new at the time* 1985 911 Carrera after the fatal crash and there was a telephone pole shaped dent halfway into the passenger compartment on the RH side. Unsurvivable in anything:
https://www.latimes.com/archives/la-xpm-1985-10-23-me-13900-story.html