I had to get ride of a car which the mice took up winter in because I could not get rid of the smell after it was stored. Since then I have always jacked my crossfire up on jacks and placed mouse traps with peanut butter on them around the jacks to catch them before taking up winter in it. This method has worked well for me and I've caught about a dozen or so mice every year and have seen no signs of them in my car.