Journal of Automotive Adventures: Trying Numerous Techniques to Keep Mice away from My BMW

My BMW E46 3 Series has been quite dependable. Unlike many of its counterparts in 2024, my car has been meticulously maintained and remained unaltered since purchase. Nonetheless, it has been a target for mice. They have nibbled on fuel lines (twice), created nests on the intake manifold, chewed on under-hood heat shielding, and damaged wiring near the thermostat. All distinct incidents. Conversely, other vehicles in the same vicinity (commonly a Honda, a Mitsubishi, and an old International Scout) have largely been ignored by local critters.

Therefore, in this chapter of Car Adventure Chronicles, I will outline my personal “BMW ///Mouse strategy” and then explore several rodent-deterrent methods garnering attention from my acquaintances and neighbors.

I opt for “repulsion” over “prevention” because the only effective way to shield against mice is to physically block their access. Otherwise, the best scenario is to repel or intimidate them—though this won’t deter every single mouse.

Is your car encased in a hermetic bubble? In that case, mice will never trouble you.

If your car is housed in a garage, ensure your insulation is airtight (mice can squeeze through tiny gaps) and maintain a clean space (no food residues, no stacks of rags that could serve as nesting grounds). Employ traditional snap traps if you suspect garage mice that you wish to swiftly evict.

In case your car is parked outdoors, combating mice becomes considerably more challenging. Sadly, this is the parking scenario numerous individuals find themselves in. Due to various circumstances, I frequently have to park my E46 outdoors. Hence, my valiant mission to fend off the creatures—like a gallant knight defending a fortress from a dragon! Yes … precisely like that.

Mice are likely to revisit familiar territories, so the first phase of any mouse-mitigation strategy must involve eradicating any traces of rodent presence. Take this task seriously—mouse droppings can be highly hazardous, especially when they turn into dust during cleaning. Nohumor! Take a moment to educate yourself before determining if you’re up for handling it.

I crafted a precise vacuum attachment using a regular tube step-down adapter, sealed with some robust tape I happened to have. This is crucial for reaching deeply into the engine bay, which, as expected, is a common nesting spot for rodents.

Next, I delicately and methodically cleaned the engine—mostly utilizing Simple Green Motorsports and Tub’o Towels. The motorsports variant of Simple Green is particularly effective on delicate surfaces and materials prone to discoloration, making it a safer choice for cleaning old plastic parts compared to harsher cleaners. The same principle applies to Tub’o Towels—it’s a mild detergent, and the wipe-on application method helps contain any cleaning spills efficiently.

I also swapped out the under-hood engine heat shield with this FCP Euro component (if you decide to purchase it, remember to get four new replacement screws as well so you can avoid being overly cautious with the existing ones).

The interior cleaning followed the standard protocol. Remember to replace your cabin filter if rodents have been an issue—they often turn them into makeshift toilets. Fortunately, cabin filter replacements are usually straightforward. I changed mine in a local auto parts store parking lot a few weeks back.

Mice detest the scent of peppermint. This age-old tale is supported by specialists and certain seasoned pest control professionals—various companies manufacture peppermint-scented products specifically designed as mice deterrents for application on vehicles.

I tested this particular one—it appeared more opaque than anticipated, and there were concerns about potential staining on black plastic, so I proceeded with caution and precision.

Surprisingly, this tape is an official Honda product. It may seem amusingly pricey, but driven by curiosity, I felt compelled to make a purchase. The tape contains chili pepper, a flavor mice usually find unappealing.

The notion is to encase wiring and vital lines in it, and in the event a mouse takes a nibble, they become disgusted and abandon their nibbling.

Mice can penetrate almost any commonly available mesh or screens if they desire, but I heard that they detest the flavor of copper and usually refrain from gnawing through the material. With this in mind, I purchased a spool of essentially copper chainmail. I stretched it across the top of the intake manifold, securing it with the anti-mouse tape.

I acknowledge they could find a way around it—and I had to be cautious where I positioned the copper as the material can conduct electricity, and I truly don’t want it transferring a hazardous amount of heat around the engine bay. I will monitor it closely.

I comprehend why a mouse would choose to dwell in my BMW. They spot “Michelin” on the tires and perhaps presume they’re entering a Michelin-starred eatery. Jokes apart, it’s more probable that mice will scale up wheels and struts than leap from the pavement up into the engine.

Therefore, I drenched each wheel, strut, control arm, and all adjoining parts with the same peppermint spray I applied to the engine bay. I don’t care if there’s plastic discoloration down there—and this is the primary pathway for mouse invasion. So, I liberally coated all four corners with the spray.

Have you ever watched the series Supernatural? They have probably produced around 1,000 seasons, so I assume you’ve come across it at some point. If not, one recurring scenario is that the protagonists create circles of salt to prevent demons from breaching a barrier.

I basically applied the samephilosophy, establishing a boundary of this driveway rodent deterrent product (purportedly safe for pets and the environment) encircling the stationary vehicle.

One drawback of this strategy (assuming it is effective) is that heavy rainfall would undoubtedly wash it away or dilute its potency, hence its longevity cannot be guaranteed.

After several weeks of periodic driving and parking with these preventive measures in place, I have noticed minimal rodent activity following the treatment. I did spot a small acorn which may have been carried by a rodent, although it is also plausible that it was swept in by the wind during travel.

Thus far, I am inclined to believe that my preventative actions have been effective. While I prefer parking indoors to prevent any rodent infiltration, I am particularly optimistic about using peppermint spray and plan to apply it around all my vehicles regularly.

I reached out to acquaintances for advice on preventing rodent infestations and received a plethora of suggestions—clearly, I am not the first to encounter this problem. However, some of these ideas are easily disproven with basic research.

Traditional mouse traps are effective. A classic Victor-style snap trap baited with a small amount of peanut butter swiftly eradicated all rodents inhabiting my garage and home. Nonetheless, I was hesitant to place a trap in an engine compartment, and I am not yet prepared to deploy traps outdoors. While placing traps inside a dwelling is acceptable, outdoor areas belong to wildlife. Given that my garage is situated in a rural setting, it serves as a breeding ground for rodents. Installing traps in my driveway feels like initiating an unwinnable conflict. Do I desire to continually slaughter innocent rodents near our residence? Not at all.

Due to my cat allergy, acquiring a mouser cat was not a viable option. However, employing a barn cat is a practical choice for reducing rodent populations if you have suitable premises.

Several individuals advised me that rodents dislike the fragrance of Irish Spring soap. This reaction may be due to its mildly minty scent. Nonetheless, I have doubts since soap is typically derived from animal fat, which in my view, might actually attract rodents.

Rumors suggest rodents have an aversion to dryer sheets. While this claim may be valid, I opted against placing any in the engine compartment. If your rodent issue pertains to the vehicle’s interior, this method could be worth experimenting.

Many suggested attempting ultrasonic rodent repellants (devices emitting noises disliked by rodents). However, experts in rodent control uniformly assert that these devices are largely ineffective. It appears that rodents are largely unfazed by irritating sounds, especially those imperceptible to humans.

My recommendation would be to forego this option and conserve both your finances and battery power.

An intriguing dilemma with a straightforward answer: Why do rodents persist in infiltrating my 2003 BMW while disregarding the adjacent 1998 Mitsubishi? The attraction lies in the BMW’s components crafted from semi-organic, such as soy-based, materials.

In essence, rodents in my vicinity simply have a preference for Bavarian cuisine over Japanese. If you have yet to encounter rodent issues and wish to assess the potential risk—conduct a search and analyze the prevalence of rodent problems specific to your car’s make and model. Through thorough investigation, you can determine the presence of semi-organic materials beneath your vehicle’s hood that could attract rodents. As it stands, it appears that older American cars and nearly all European vehicles are highly favored by rodent populations.

I sincerely hope that my ongoing battle with the rodents near my New York garage has stagnated. As long as they avoid converting the metal frameworks of my cars into their personal dining establishments, they are free to roam the premises at their discretion. That said, if they encroach on Bramble’s dog enclosure, it will become her territory, and all bets are off.

Are there any other methodologies that I may have overlooked, which you would like to share or recommend I experiment with if I discover yet another acorn stowaway beneath my vehicle’s hood despite all these efforts?