There are so many demands placed on materials used in a car—they need to last for years, be easy to clean, withstand extreme temperatures, and so on—that expecting them to smell good is asking a lot.
But those tough requirements are why automakers hire people like Tori Keerl, a materials engineer at Nissan’s Farmington Hills, Michigan engineering center. She oversees a team of scent experts who meticulously analyze the smells of everything that belongs inside vehicles like the Nissan Pathfinder SUV and Frontier Pickup. I met her on the show floor at the New York Auto Show to talk about smells and put my own nose to the test.
Keerl was originally hired as a plastics materials engineer, but, partly because plastics make up the majority of materials in a non-luxury vehicle, she was soon given overall responsibility for the smell of Nissan vehicles inside.
“Every time we start a vehicle, we have to test the smell of it,” she said.
As a new model is being developed, Keerl and her team sniff out individual vehicle parts, such as steering wheels, seat cushions and sun visors, before they are installed in the vehicle, to ensure they have a pleasant – or at least harmless – smell.
“Then we put them in the vehicle,” she said. “We sit in the vehicle and make sure that while we’re in the driver’s seat and you’re in the back seat, you smell that good new car smell.”
Front seat odors can be enormous unlike smells in the back seat, she said. In the front seat, there’s a far greater choice of materials near the nose. Besides leather or cloth seats, there are the plastics on the dashboard and whatever the center console is. There are also all the connecting materials, threads and glues that hold these things together. In the back seat, you’re much more surrounded by just seat materials. There are seats in front of you, behind you and below you. Then there is the smell of the carpet material underfoot.
Even if all the components in the car have been pre-sniffed by then before being installed in a prototype vehicle, there are still surprises. Like cooking, some smells that are good or even very nice can come together on their own to create one hell of a funk. Or sometimes there was a smell that somehow got overlooked in all that earlier sniffing.
Then Keerl’s team must begin their investigation. She and the members of her team are all “certified noses”. (There is training and certification that includes carefully conducted odor identification tests.) You begin your investigation the same way you would try to find a strange smell in your own car. They methodically sniff every inch of the inside of the car until they can narrow down where the unpleasant odor is coming from. Once they’ve narrowed down the odd smell, they start figuring out exactly what material or combination of materials is causing it.
Often a surprising odor in the fully assembled vehicle is due to a supplier changing some aspects of how a part is manufactured. In that case, Keerl said she will work with the supplier to find out what has changed and see if the problem can be fixed.
Since a person’s sense of smell can change over time, even in everyday life, the professional smellers are regularly re-certified through blind smell tests. You will be given unlabeled vials of different scents and asked to identify each one.
I tried it myself and it was surprisingly difficult. Smelling an odor without seeing where it’s coming from is a bit like seeing your child’s first grader at the supermarket checkout. You know you’ve met this person before, but without the normal context, you can’t remember where or how.
I opened my first vial and smelled something vaguely pleasant and rich. It smelled… earthy. As that word came to mind, I realized I smelled dirt. It was a can full of dirt. The next bottle smelled kind of woody. I didn’t realize I smelled pine shavings, but when Keerl told me I felt a little stupid. Pine has to be one of the most recognizable smells in the world, but without being able to see the wood in front of me I couldn’t quite place it.
Because attitudes toward smell vary from one culture to another, Keerl’s work focuses on cars destined for North American customers. Car buyers in Europe and Asia might not appreciate a smell that we find absolutely appealing here. They may not like the “new car smell” that Americans appreciate and prefer no smell at all.