If an animal is suffering I see no problem in ending it's pain. Some say leave it be and let nature take it's course but when a deer or any animal is hit by a car nature had nothing to do with it and the animal should be put down.
I love to hunt deer and have a freezer full of fresh meat but every time I harvest a deer get very excited when I find it but then after I calm down a bit feel sorry for the deer in a way but that is what we as hunters are here for, to control the population. I am a hunter with respect for the game I hunt and fish for not a cold blooded killer like some organizations make try and make the general public beleive. This is a very good tread and I am glad to see people feel the same as I do.