I can vouch for peppermint oil! I also had an infestation...IN MY CAR!! I'd gone shopping, and when I came back to my car, there were TWO brown and white mice on my drivers floor mat. UGH!!! one dead, one not quite. Luckily I was able to pull the mat out and leave them...sorry... no proper burial. When I got home I noticed tons of little pieces of foam behind both the drivers and passengers front seats...yep they had both made nests in my seat backs, and yup...left their babies behind!! DH had to handle it from there, and by the time he finished taking the seats apart, he removed 9 babies. He bought little plastic bottles with holes at the top, added cotton balls, and soaked them in peppermint oil. They now hang on the door handles of the back seat. There's one in the engine compartment also. For several weeks I made him drive my car, and I took his....just to be sure!! They haven't returned, so I'm back to driving my own car!