Mate an adult rat can fit through a hole the size of a 50p, so stoping a mouse is near impossible. no car is (hole) air tight, or you wouldnt be able to close the door due to air pressure inside.

only advise is store the car somewhere else, or is thats not possible bait around and under the car.

probably best to use traps as well, cos weve used poison which works but they crawl in the car and die in there, not nice!!!!

we have chickens and live in fields so rats and mice are an everyday thing, ive even found a mouse in side a light switch, and with the 2.5mm wire the hole must have been half the size of a 5p!!!!