I agree with Hankos response (above)..... in the 2 cars that I store for winter, I place mothballs in small plastic containers by my wheels, and one moth ball into each of the rear exhaust tips and a few mothballs generally scattered beneath the car . I also place mothballs in 3 areas within the engine bay....... no mothballs ever in the cabin of the car. I have been doing this for years and so far no issues with mice. One of my neighbors had the misfortune of having mice set up shop inside the engine bay of his Audi. Pretty much all of his wiring was chewed through...... thousands in repair costs.... luckily covered by his insurance.