they could chew up the wires. I had a customer complained about not enough air was pushed out of the center vent. turn out there was a dead mouse stuck in there. My old 525 had the same happen, mouse moved into the engine room, good thing was I found it soon and the traps worked, not much was damaged except some paint was chewed off and some droppings. maybe you can put some mouse traps on top of the take manifold as I did before.

 

This can turn into a very expensive issue :crying:
I had a rat chew up the underhood insulation. This post shows the damage that occurred overnight.
Mice chewing up the wiring could total the car oohhh:

 

This can turn into a very expensive issue :crying:
I had a rat chew up the underhood insulation. This post shows the damage that occurred overnight.
Mice chewing up the wiring could total the car oohhh:

Identical to my experience with the addition of chewing up the firewall insulation in the vicinity of the DME E-box. Found a nice little nest behind the throttle actuators...as if they aren't problematic enough.

 

Seems to happen more in cold weather when they are looking for warmth.

Can be a serious issue if they are in there for a long time. I remember this story.

Mice killed my M5! - SmokStak

 

Given enough time they will absolutely destroy your car! Here are some pics of a friend's Elise after mice moved in. Most of the damage was done to the wiring harness....mouse traps are cheaper.

 

To battle the rat problem, I initially installed some glue traps (easily found at any hardware store). High under-hood temperatures would melt the glue and create a mess. Version 2 of my rat trap mod was Trapper Glue in plastic containers. Never caught a rat, but also no more damage. Removed the trap when I changed spark plugs.

 

Rodents are particularly destructive. They will gnaw through wiring, connectors, sensors, hoses, metal piping, and plastic covers/housings. Traps are good but not just under the bonnet, but under the car, near garage access points as well. Chili power, spray, flakes will also help keep the buggers out (it gets up their noses and you can guess the result).

Another good reason not to de-cat' your beast. :grinyes:

Good luck getting rid of the mice.