Shem you legend. All the best for the poor kitty - I hope it survives and leads a long happy life. And I hope whoever hit the poor thing and didn't stop has four punctured tyres and a busted gearbox that will cost $1000 to fix.
You did the best you could for that little kitty but I know it hurts and how angry you must feel.
My brother who now works as a firefighter once saw an injured kitty on the side of the road. It aappeared that the cat had been hit by a car. He stopped and tried to flag down help - he was a student at the time, a big strapping aztheltic type fellow. But not one car, even a police crusier, would stop!!! He took the cat to a vet and the kitty was a fighter and survived and our family adopted her. She is still very skittish though and runs at a new sound and especially new people. But when I do visit my folks, she will sleep with me at night or will jump into your lap. But she likes to hide. All the other pets - including my YY - seem to sense this kitty had a hard time at some point in her life and are kind to her. My beagle used to be VERY protective around her.
I am so sorry the cat you found had such severe injuries and I too have to wonder how some ppl can be so cold hearted!