My brother tells a story about a guy he knew that took his wife and kid to pick up the mother-n-law around Christmastime. They were driving back toward his house when he spotted a really nice buck by the road. Instinct took over, and he rammed the deer, knocking it some distance. He then jumped out if the truck, ran to the buck, took the knife from his belt and delivered a series of blows to the animals ribcage. When he finished, he looked up, satisfied, and noted that the kid was crying and the wife and MIL had looks of horror on their faces. Oregon redneck....
Didn’t the kid like venison?
That said, the thing to do is slit its throat, though I imagine that if its just been hit by a truck it won’t be that obliging. I’ve heard two stories of guys who were spotlighting and slit the throat of deer that they thought they had stunned.
The county my parents have moved to in Ohio has the highest density of deer in the state. They know a guy who has a “hunting car.”