I've come to the conclusion that the best solution for this dilemma is to keep an adult grizzly bear in your car at all times. Hit a deer - release the bear to put the poor creature out of its misery (and feed your car-bear as well).
At first I thought keeping a pack of wolves in your car would be best, but that's kind of ridiculous when you really think about it.
(Insert random tough-guy quote here)
"See my gun?? Aren't you impressed?" - Anonymous sheepdog
Guns - the alternative to running for your life.