If you hit a skunk with your car, do not approach or touch the animal. Contact law enforcement authorities or your local animal control. Do not leave the scene until you are told you can do so.
Once the skunk is dealt with, the next task is to remove the smell from the car. Distilled white vinegar, baking soda and solutions of mustard powder can all be used. You will need to clean both the interior and exterior of the car; you will probably want to replace the cabin air filter as well. Alternately, you can take the car to a professional detailing service for cleaning.