I've seen a lot of rodent damaged cars over the years. I've raised hoods in the shop and had rats jump out quite a few times. It's interesting how they go for certain wires on certain cars. I've heard many different theories on why, all related to type of wire insulation used. They will go for these wires first (usually the small sensor or fuel injector wires), but if they're not scared away they'll branch out to all the wires, vacuum hoses and eventually the plastic parts.
The worst one i ever saw was an old couple from Rossmoor that came home from a long European vacation. They thought it was just a dead battery, had it towed-in, the rats had chewed every wire on that car... insurance company totalled it.
If you live in an area where rodent infestation is an issue and park outside, the best ways to avoid damage, imo...
1) A really good outdoor cat that does his job well (a very rare thing to find these days.)
2) Drive the car, or at least start the engine, at least every couple days to scare them off.