Rooster hit by a car

I came home yesterday to evidence of chicken hit and run, bunch of feathers along the road. I didn't see a dead chicken, none in the ditch, I found him under the car port.

Pretty sure he has a broken wing, not using one leg, blood on his beak. He's breathing a little heavy with his mouth open. I left him under the carport with a little cup of water, to see if he would make it through the night.

This morning he was in the same place, still the same. I lifted him on to a chair, so he would be more comfortable. Shortly after, he started doing some strange breathing thing (he looked like he was crowing, with no sound, but a bit rattly). I thought he was on his way out, put him on the grass so he could feel the sun. He worked past it. Put him back on the chair.

What do I do with him? Is there any chance he can make it?

I can't cull him, I feel so bad that he is suffering. My partner is deployed with disaster relief, and he told me to do the same. I just can't bring myself to do it.

I've been syringe feeding him a bit of water, and (this is probably the wrong thing to do I'm sure) I gave him 1ml of childrens Tylenol.

All our chickens free range, but we do lose a few a year to cars. It's usually a definitive death though, I've never had one of them survive.

I've put him in an old laundry basket with a towel, brought him into the house. The other chickens were harassing him.

I can feel a small amount of crepitus around his chest, but not too much. His breastbone is intact.

His leg isn't visible deformed, one toe looks a little crooked. I honestly have little idea what to look for. His biggest issue right now is the breathing, he's coughing a little bit now, and breathing is still laboured.

His head is down now, and his eyes are closed. I think he's done.