I don't have mouse problems, but if I leave any of my vehicles sitting for for a than a few days, I have wasps building nests in any crack or crevice they can find. 

last week I started the 848cc Moke up after being in enclosed storage for several months, several mouse nests blew out of the exhaust pipe! I'm surprised the 848 had enough puff to do that!

Here are some mini nuts .

Out of the fresh air duct. Must be mice again. I have my mini in a detached unheated concrete floor wooden walled garage with a window fan for ventilation 24/7/365. In 22 years, I have had 3 infestations despite driving it every 2 weeks all year long. Once was a nest built in the engine compartment along the firewall. Second was a nest in the glovebox along with 6 dead babies. This third evidence was not a nest (yet), just a stockpile. They must have entered the intake behind the grille and ascended the duct, stopping to pile them up at the fresh air butterfly closer. I saw one nut, pulled it out, then realized there was pile of them. Kept pulling them out one at a time..... 52 in all !