You might not think it, but keeping mice out of cars (especially those that are infrequently used) can be frustratingly difficult. They seem to enjoy doing expensive damage, nibbling on important wires and getting into the climate control system behind the dash.
The first thing to do to make your car less appealing to mice is to clean it well, especially the interior and luggage compartments, being sure to remove any obvious sources of mouse food (garbage, cardboard, paper, human or pet food, etc..). If you’re storing your car inside ensure that the building itself is also clean and in good shape, with no obvious entrances for small animals.
The most effective solution to keeping mice away might be the old standby, the cat. A cat will not only catch mice, but their smell tends to scare rodents away. To keep mice out of the engine place moth balls around the engine compartment in breathable bags or socks. Dryer sheets should keep them out of the interior and keep it smelling fresh.
Traps positioned around the car can also be effective, however it’s not recommended to place traps in the car as they can leave behind a rotten smell if they do trap an animal and it goes unnoticed. Rat poisons are not recommended for the same reason, there is the possibility that a mouse might get into your car after eating it, or that another animal like a bird or cat could become sick by eating a poisoned mouse. Commercial rodent repellents are a better alternative to poisons. Animals also tend to dislike sudden noises or flashing lights. A stereo or a couple of noisemakers fashioned out of pieces of metal may help scare them away, as might a motion lamp or strobe light.
If you are storing your vehicle for an extended period of time it is recommended that you block any openings to the engine (such as the exhaust and air intake) and climate control system. Also remember to close your windows and ensure that your weatherstripping is in good shape. A combination of these steps should make you much less likely to have a rodent problem in your vehicle.