I've had mice chew up computer network cables, and my nice 10AWG extension cord, but never wires in the vehicles (that I know of).
My old Renault Encore had a design where the battery was located in the cowl right above the firewall penetration of the main wiring harness, as well as one of the brake lines. Needless to say, I had a brake line leak, and as the car aged, the lights and connections started doing odd things. Later versions of the model had the battery moved to a location away from so many critical components.
One of the more annoying things that a critter did to me was a squirrel that would hide a nut in the steering mechanism of my pickup. I'd get in and start driving, and find that I could make a right-hand turn, but not a left-hand turn (or straighten the steering after turning). I'd take the nut out, and a few days later, another one was put in the same spot.