How to Protect Your Car From Rodents
Consumer Reports offers clever solutions to critters nibbling at your car's wires
Rats! You can buy the most reliable car on Earth and still find convoluted electrical gremlins, fluid leaks, and even outright failure when rodents take up residence and begin chewing on wiring, hoses, belts, and other critical car parts. Cars stored over the winter are at particular risk, thanks to their many critter-sized nooks that provide shelter from the elements.
Rodents are not just a risk for cars parked outside. Vehicles inside enclosed home garages can attract chipmunks, mice, and squirrels, too. This problem isn’t limited to newer cars that use more plant-based, biodegradable materials to reduce waste.
According to pest control company Terminix, rodents have to constantly chew on anything to keep their teeth from growing too long, and they’re not picky about what to gnaw. A study published in the journal ACS Sustainable Chemistry & Engineering backs this up; researchers found that the inclusion of soybean oil in various industrial materials—including common ones used in cars—didn’t have any meaningful effect on which material they chewed. PVC was their snack of choice in the test, with mice gnawing off nearly the same amount from both the soy-free and soy-containing versions. (Several class-action lawsuits have also been filed against major automakers in recent years, alleging that soy-based products were responsible for an uptick in rodent damage, but these court cases were later dismissed.)
Other factors are likely to blame for an increase in rodent damage in recent years. A representative from the pest control company Orkin told Consumer Reports that there was a rise in rodent damage during the pandemic, partly because more people were working from home and driving less frequently, leaving plenty of stationary cars for mice to move into.
Rodents themselves are changing, too, in ways that make pesticides less effective. Researchers at Rutgers University found that 84 percent of the urban house mice they studied had at least one genetic mutation associated with rodenticide resistance.
Photo: Mike Crossen/Consumer Reports Photo: Mike Crossen/Consumer Reports
How to Keep Mice Out of Your Car
Keeping rodents away from your car is the most important thing you can do, especially as they become more resistant to pesticides. The best way to prevent damage is to catch critters before they reach your car. Placing snap traps in your garage or around the outside of your vehicle is the easiest and most effective method.
Live traps can be a more humane option, but they require frequent—ideally daily—checks for captured critters. You’ll also need to travel a considerable distance to release the animal and take extra precautions when doing so to avoid contact. Trap maker Havahart advises releasing captured animals at least 5 miles away if local laws allow.
Be careful to keep domestic pets and children away from dangerous traps or captured animals.
In addition to setting traps around your car, you should seal your car off from rodents as best you can. The easiest way to do so is by storing your vehicle in an enclosed garage. Keep the garage door closed as much as possible, and seal any gaps or holes you find in the exterior immediately. Look for gaps around garage windows and doors that could provide possible entry points for rodents. Weather strips under the side doors can help seal them. Likewise, inspect the vertical seals on retractable garage doors for damage. If you park outside, consider using a car cover like this one from CoverSeal, which is designed to form a continuous seal around the bottom of the cover to discourage rodents from sneaking into your car.
Regardless of whether you park outside or in a garage, keep your car as far away as possible from rodents’ food sources, such as trash cans, forests, and gardens. Avoid parking your car near prime nesting materials such as newspapers, cardboard, straw, rags, insulation, and patio furniture cushions.
If you park in a garage, don’t store trash cans used for food waste there, and don’t leave nesting materials loose where they’re easy for rodents to access. Secure any potential critter home furnishings inside a sturdy box, and keep tasty treats like open bags of birdseed in the house instead.
Never keep food or garbage in your car, either, because that scent can lure rodents inside.
Rodents aren’t just looking for a prime, open location close to the amenities they need to live. Just like us, rodents prefer homes that are calm and quiet, making a sitting car extremely attractive.
“A car protects the mice by offering not just a hiding location, but a warm location,” says Changlu Wang, a co-author of the Rutgers rodent study. “The longer you park a car without driving it, the more likely rodents move in.”
Move your car regularly to discourage varmints from taking up residence. You can also honk the horn before starting the car to scare away any napping critters.
Car Rodent Repellents That Work
Besides adding traps to catch any furry vandals who have moved in, you might consider one of the many gadgets or substances designed to drive rodents out. Some are more effective than others.
There are specially formulated spray products designed to deter rodents. If you store your car in a garage, you could mist one of these deterrent products under the hood and around the vehicle. Peppermint oil and cayenne pepper can sometimes deter rodents, but spray products with these need to be reapplied routinely, because they can wear away and rinse off. This is why Wang says that parking away from things rodents love is better than relying on smells and tastes they hate.
Terminix also advises that rodents can get used to off-putting smells, reducing their effectiveness over time. Placing mothballs under the hood, for example, may help for a brief time—it’s another smell many rodents dislike—but it’s not a long-term solution. (Also, don’t use mothballs inside the car, or you’ll be stuck with that awful smell.)
Photo: Consumer Reports Photo: Consumer Reports
A technical service bulletin from Honda offers another clever solution: rodent-deterrent tape, which is essentially an electrical tape treated with super-spicy capsaicin, which Honda describes as “the stuff that puts the fire in a bowl of five-alarm chili.” The tape (part number 4019-2317) comes on a 20-meter roll—about 22 yards—and is available through dealers and online for $57.
We bought a roll of Honda’s rodent-deterrent tape to check it out. Beyond the cute rat graphics and gray color, it deceptively seems like regular electrical tape to us humans. There is no tear-inducing odor, but it does carry a label warning against prolonged skin exposure. Despite dares and double dares, we did not taste it and will trust that it is enough that when wrapped around key wires underhood, it will deter even the most ravenous varmint.
Some companies also offer ultrasonic devices that emit sounds to deter rodents, but at a frequency humans can’t hear. However, pest control company Orkin says these devices have a limited range, and manufacturers have received warnings from the Federal Trade Commission for decades for making unsubstantiated claims about their efficacy.
Other suggestions for dealing with rodents under your hood include installing metal mesh around wiring harnesses and rubber hoses and across any openings where rodents could crawl into your ventilation or intake systems. Just make sure these don’t touch any moving parts or exhaust components.
If the rodents are winning the war despite following these tips, or they left major damage behind, contact a local pest control service. They are trained to combat stubborn rodent issues and can address your specific challenges.
Photo: Mike Crossen/Consumer Reports Photo: Mike Crossen/Consumer Reports
How to Clean Up Rodent Damage
Rodents and their droppings can carry dangerous and even deadly diseases. If you find them in your car, it’s important to clean them up properly.
According to the Centers for Disease Control and Prevention, do not use a vacuum cleaner, as it may cause virus-containing droplets to spread in the air. Instead, spray a nest or evidence of an infestation with a disinfectant (not bleach, since it will ruin your upholstery and damage car parts) and let it sit for 5 minutes before removing it.
Wear disposable gloves and use disposable paper towels to handle any nest or droppings, and wear a protective mask to avoid inhaling dust. Then clean the area again. Wash your hands before and after removing those gloves, too.
To remove stains, only use cleaning products that are safe for the materials you’re cleaning. If you find rodents or droppings in the vehicle’s air intake, dispose of that air filter, disinfect the surfaces the rodent touched, and replace the filter with a new one.
If this sounds like a bit much to take on yourself or you’re unsure where to start, contact a local detailer, explain what happened, and see how they can help. Some detailers also offer mobile services, so you wouldn’t need to move the car.
