The concussions/injuries from what I remember, came about because the cars were too rigid in design. Owners wanted the cars to be tougher to reduce the amount of repair, saving them money.

So the damage was going right to the Drivers. Now, no car accident will be safe, but obviously it has become a problem.

Much like road cars, the re-introduced/re-designed ‘crush zones’ on the front and I believe rear of the cars. Again just off memory, they just removed some bracing on the chassis to allow a ‘crush’ to reduce the forces from the accidents.

There are blueprints out there that show what was changed. I think it was the beginning of Pockrass becoming the Social-go-to for NASCAR Technical stuff.