It seems pretty obvious he did no suffer much and was killed rather quickly.
Crushed skull to that extent and you cannot survive more than 2 minutes.
My fear was to one day find him HALF MANGLED and not dead from a austin car accident.
i looked down on that road a couple of times when he was late, wondering if I would find him. I had one goal: never leave him without supervision for more than 1 hour when outside. He was that very unreliable, the only outdoor unreliable cat I ever had.