Updated July 2026 Mice and rats can cause thousands of dollars in damage when they nest under the hood or chew through wiring. Car rodent repellents may reduce the risk, but the products work in different ways and few are dependable when used alone. This guide compares seven options, including peppermint spray, repellent pouches, under-hood ultrasonic devices, rodent-deterrent tape, copper mesh and outdoor motion deterrents. It also explains which product makes sense for each type of rodent problem. Start here: For help with car wiring, garbage cans, home entry points and insurance questions, visit our Rodent Damage Prevention Guide. Quick More…