Engineers from the Ford Research and Innovation Center have been working with the University of Michigan to find the grimiest bits inside your car and their results are, well, not all that surprising. Turns out, the most microbe-infested parts of our cars' interiors are the same spots we touch the most. The team took samples from 10 locations in employees' cars including steering wheels, radio buttons, shift knobs, and window switches.

"Our findings suggest car interiors are complex ecosystems that house trillions of diverse microorganisms interacting with each other, with humans, and with their environment," says Dr. Blaise Boles, assistant professor in the U-M Department of Molecular, Cellular and Developmental Biology in a press release.

The two most likely spots to encounter some of these bugs is on your steering wheel around your car's cup holders. "The console area near the cup holders is a common location for spilled drinks, so it provides an ideal feeding ground for microbes," says Cindy Peters, Ford Motor Company technical expert.

The point of the study wasn't just to gross out drivers and encourage cleaner driving habits. After identifying the grossest areas, the team set to work on developing paint additives that might one day discourage the growth of microbes. Ford is currently testing interior coatings infused with Agion, an antimicrobial, silver-ion compound. If the long-term, real-world tests show Agion to be effective, you might one day experience the sweet smell of their success first hand.

"We can't control everything that contributes to stains and odors in our cars and trucks," Peters says in the press release. "But we're doing our part to maintain a pleasant cabin environment for our customers over the long haul." Get more of the dirt on the, well, dirt in the press release below.

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Ford and University of Michigan Researchers Team Up to Fight Microbes in New Cars and Trucks
  • Operating in a wide array of conditions, cars and trucks can become a breeding ground for a variety of microorganisms that cause odors and discoloration of vehicle surfaces
  • Americans spend approximately $2.3 billion annually on air fresheners
  • Researchers from Ford and the University of Michigan studied vehicle interiors to learn where microbes grow and evaluated antimicrobial additives for coatings
  • Adding silver-ion-based Agion® to paints may significantly inhibit microbe growth
We can't see them, but we are surrounded by tiny microorganisms that can have undesirable effects on the surfaces around us. In cars and trucks, these microscopic organisms including mold and mildew can quickly take hold and spread over a variety of surfaces leading to discoloration, and even unpleasant odors.

"Vehicle cabins are exposed to a wide variety of environmental conditions that can make them microbial breeding grounds," said Cindy Peters, Ford Motor Company technical expert. "Based on growing consumer desire for health and wellness solutions, we decided to take a look at the interiors in Ford vehicles with the goal of creating a cleaner, more aesthetically pleasing environment for our customers."

Market research firm Mintel reports Americans spend approximately $2.3 billion annually on air fresheners including aerosols, plug-ins, slow-release and hanger products found dangling from car mirrors.

Many consumers are sensitive to chemicals or simply don't like the artificial scents of many air fresheners, so a solution that proactively reduces the source of odors for the life of the vehicle might be appreciated.

Engineers from the Ford Research and Innovation Center in Dearborn have been collaborating with a team from the University of Michigan (U-M) led by microbial ecologist Dr. Blaise Boles to evaluate the concentration and growth of microbes in vehicles.

Peters and her colleagues collected samples from a variety of company and employee-owned vehicles. The samples were then cultured and analyzed at a U-M laboratory in Ann Arbor, Mich.

The team took swabs from 10 locations in the vehicle interior including the steering wheel, radio buttons, door handles, window switches and gear shift knobs. The U-M researchers found significant bacteria growth at most of the test locations with the highest concentrations on the steering wheel and the area around the cupholders.

"Our findings suggest car interiors are complex ecosystems that house trillions of diverse microorganisms interacting with each other, with humans, and with their environment," said Boles, assistant professor in the U-M Department of Molecular, Cellular and Developmental Biology. "The long-term goal is to define the microbial ecology of the car interior and to optimize the design of car interiors to promote comfort and environmental sustainability."

"We weren't surprised to find microbial hot spots on the steering wheel, since that is where a driver's hands are most of the time," added Peters. "The console area near the cupholders is a common location for spilled drinks, so it provides an ideal feeding ground for microbes."

Americans also spend more than $1 billion annually on a variety of products including lotions, wipes and sprays to fight microbial growth. Having identified the source of the microbes in the vehicle cabin, Peters and technical leader Mark Nichols went to work with interior coatings supplier Red Spot Paint and additive supplier Sciessent LLC to develop and test coating formulations that could resist and potentially even reverse microbial growth.

The team focused their attention on three commonly used and EPA-approved antimicrobial additives including silver-ion, ammonium salt and polyolefin wax with a nano-silver coating. Panels painted with four different formulations were then evaluated back at the U-M lab to assess the growth rates of microorganisms.

Parts coated with paint infused with the silver-ion additive sold under the trade name Agion®, contained lower microbe growth than the control parts with the current production paint. Agion, based on elemental ions, works by starving, sterilizing and suffocating the microbes to prevent them from growing and reproducing.

Cars and trucks generally have a much longer life span than most antimicrobial-treated products, and they operate in a wider range of environmental conditions. Drivers expect features to continue working and surfaces to remain intact even after the vehicle has been on the road for many years. Peters and Nichols subjected the specially coated test panels to an accelerated aging process to evaluate their microbe-controlling properties after the equivalent of years of exposure to sun and heat.

Even after simulating many years of use, the microbe growth of the Agion-infused coating changed very little. The additive also had little impact on the gloss and color change of the surfaces over the test period. Parts with the antimicrobial-treated coating are now undergoing real-world testing in a number of Ford development vehicles, and the coating is being evaluated for potential use in future Ford vehicle programs.

"We can't control everything that contributes to stains and odors in our cars and trucks," said Peters. "But we're doing our part to maintain a pleasant cabin environment for our customers over the long haul."