Your car’s lost its pep? Pop open the hood, maybe a rat’s to blame.

A rat scampers across a grassy patch next to a paved lot at a shopping center in north suburban Niles, picks up a crab apple and carries the bitter little fruit under a parked car and upward — into the engine compartment.

Soon, the rodent emerges empty-handed and repeats the drill while the vehicle’s owner is inside a nearby storefront, oblivious that a creature is piling up a food source under the hood where there’s also likely a nest — all of which could wreak havoc on expensive auto components over time.

Not oblivious to this kind of dynamic are local auto mechanics who say rodent infestation in engine compartments is not only common in the Chicago area, but with the weather now turning colder, probably ramping up with rats, mice and other undesirable animals now looking to build a home in a vehicle.

“It’s the perfect time,” said Joe Santoro, owner of BJ’s Complete Auto Repair at 3820 N. Harlem Ave. “They’re going to be looking.”

Santoro would know. At the time he was speaking to a reporter over the phone, a Ford pickup truck was at his garage awaiting parts to replace wiring and foam that had been chewed through by what’s likely one or more rats.

“We’ve been seeing it a lot,” Santoro said. “It’s pretty rampant, it’s been explosive in the last three to five years.”

“Part of the problem is the rodents in the city,” he said, while another factor is that some auto components are now soy based, which apparently is an attractive food source to voracious rats.

“I see 2,500 cars a year, I’d say maybe this year I probably saw 40 or 50” vehicles that had some degree of rodent infestation, Santoro said. “It’s not a high percentage, but it’s increasing.”

Luckily, he’s never encountered live rats in a vehicle, though he’s seen what looks to be active nests — and “we did find some dead ones,” he said.

Horror stories abound in Chicago of rats making their way into the underbelly of vehicles after a driver parks near dumpsters, a restaurant or some other food source — or even a seemingly safe spot like a residential garage.

There also have been incidents where rats find their way into the passenger compartment of a car through a window left down and end up burrowing under the floor fabric — a well-known receptacle for crumbs and other bits of food for any motorist with younger kids.

"The worst one we ever had was a customer of ours, she had two cars, she used one and the other one was left on the street," said Pete Rosquete of Doc Able's Auto Clinic in Evanston. "They got in under the carpeting in the back . . . they made a mess . . . we had to take the back seat out."

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One remedy, peppermint repellent

Once infestation areas are cleaned or fixed up, to keep rodents from coming back "we use some good old-fashioned peppermint smelling stuff that they sell at Home Depot and it takes care of it, they don’t come back," Rosquete said.

Santoro said his shop recommends dispersing moth balls in the corners of engine areas.

Leo Hernandez of Eliot’s Complete Auto Repair at 3658 N. Lincoln Ave. said his shop advises people to buy repellent bags off Amazon for the same purpose.

A search of the online marketplace shows a number of environmentally friendly pouches for sale that are said to deter rodents in vehicles among other places.

The Automatic Trap Co. distributes what are described as eco-friendly traps to kill rodents, though the California company's Richard Cao doesn't usually recommend traps for inside a vehicle as "we try to avoid anything dying in your compartment."

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Cao said "even though I sell traps" it's "more important to change the environment first, you need to have a clean environment" that doesn't attract or sustain rodents.

For instance, "if you 100% have to have a garbage bin" near your car, it "needs to be sealed."

Avoiding toxic poison is important, too, because if a rodent ingests it, another creature up the food chain that feeds on the dead or dying animal then could also become sick or die, experts said, pointing to cats and birds of prey as unintended victims.

‘The rat was blue’

Hernandez recalled a customer coming in earlier this year because of an issue with windshield wiper fluid.

“Every time he would spray the washer fluid, there was a foul smell coming out,” Hernandez said. “Turned out there was a dead rat in there,” inside the “reservoir.”

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“We pulled it out and the rat was blue,” he said, adding they took a video of the creature given how odd the situation was.

Hernandez said many city dwellers park their cars for extended periods — but that can provide more opportunities for rats to hunker down.

“We try to tell our customers they have to drive their car or move it around,” he said. “Especially if they park close to an alley.”

Trash bins are common food sources for rats, so parking near one can spell trouble. Same with parking in a garage with, say, bags of bird seed or dog food nearby.

"It’s nature so they are going to find shelter," said Lucus Howard, shop manager at Boltz Automotive at 707 W. 119th St., who in addition to rats has seen opossums and raccoons in engine areas.

Said Jeff Johnson of Highline Automotive in southwest suburban Countryside, "It is a very common issue, it’s just one of those things."

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Chicago’s Department of Streets and Sanitation deals with rodent problems in the city, but in public settings rather than private vehicles, though an infestation in an alley can obviously lead to rodents in a nearby car.

The city agency fields between 40,000 and 45,000 rodent calls a year, officials said, and poison is among the tools used to keep down the rat population.

A 2017 study by the National Pest Management Association, a trade group for the pest control industry, found that nearly a third of Americans have experienced vehicle damage from rodents.

And that damage can be extensive and expensive, according to the Insurance Information Institute’s Mark Friedlander, who said: “Nearly 100,000 comprehensive auto claims are filed annually in the U.S. because of rodent damage to a car’s wiring.”

“Repair costs depend on how extensive the damage is,” said Friedlander, who described his group as a nonprofit research organization based in Malvern, Pa. “A few chewed wires may be a modest repair, while wiring harness damage can be a far larger expense.”

“For minor repairs, costs run approximately $500 to $1,000. For more significant repairs, the cost typically ranges from $1,000 to $6,000. However, we have seen claims run as high as $10,000-plus for major damage.”

Robert Herguth / Sun-Times

Car damage from rats averages $3,900

Citing 2025 data, a spokesman for State Farm insurance said "the average comprehensive claim payment for rodent-related vehicle damage was approximately $3,900 nationally," with those fixes involving collisions as well as infestation damage.

The Illinois-based company's "latest animal-related claims data ranks rodents as the second most common animal involved in claims."

"Rodent damage is typically covered under an auto policy’s comprehensive coverage, not collision coverage."

Damage from rodents can sometimes render a vehicle inoperable, while rodent excrement can sicken humans, according to the National Pest Management Association’s Michael Bentley, who recommends regularly checking an engine compartment and, if there’s an infestation, seeking out a licensed exterminator.

Bentley isn’t sure how much the soy coatings are responsible for attracting rats and mice, but with vehicles including more electronics than ever, there’s more to chew — something rodents like to do even if they’re not hungry.

Other animals including cats sometimes seek refuge inside the engine areas of cars — but it’s likely more about warmth rather than seeking out rodents to eat.