Never had a problem with a vehicle left outside, as soon as it's garaged, then the problems start! Pickup was in the garage all summer and a mouse took up residence and wouldn't take no for an answer. Set traps, sticky and snaptraps, no luck. Tried various repellants, nope. Kept building nests under the driver seat and I kept removing them, what a mess. Finally, one day I go out to do the usual clean-up and here my little furry friend is dead in one of the snaptraps with a litter of 7 dead little pups all around her! No wonder she was so insistant. And of course, I felt bad...but I got over it, I don't think she did.