The Curious Engineering Behind the Scent of Our Volvo Cars

What goes into creating the smell of your car? Two fragrance experts talk about our sense of smell, the materials in our cars and warm summer days.

Freshly brewed coffee inside a cold car on a winter's morning, the distinct smell of a new car, a mix of moisture and plastic in an old Volvo 240 that your grandparents might have driven… We all have strong memories connected to scents. But why do cars smell the way they do?

We hunted for the answer at our Materials Centre in Torslanda, Gothenburg, Sweden. Here, Annelie Synnerdahl and Hanna Sundqvist, both chemical engineers, investigate all materials used in a Volvo car. And that’s anything from tiny pieces of fabric to a certain accessory – or a whole car. All these are heated up in advanced chambers so that their scents can be collected and analysed.

“We make sure that the air our customers breathe in our cars is as clean as possible,” Hanna says. “We have high demands on our suppliers – with requirements getting stricter all the time. We don't even want to see traces of certain substances, while others are allowed but regulated.”

The White Elephant, one of the three chambers used for this work, fits smaller parts like a steering wheel, a child’s car seat, or a carpet. “The conditions inside the chamber should mirror the environment in a car,” Annelie explains. “Imagine a car parked in full sunshine on a hot summer day. To replicate this environment, we perform tests at up to 95 °C (203 °F). At that temperature, the heaviest hydrocarbons are released and collected on a foil, placed on a cooling plate to simulate the cold windshield.”

Clean air with controlled humidity is constantly supplied to the chamber during the test. Annelie puts her nose to the pipe, where the surplus air exits and the smell can be assessed.

“All plastic materials emit chemical substances in small amounts and most substances have a certain smell,” Annelie says. “We often talk about an odour threshold, which is the concentration at which a substance starts to smell. Unfortunately, certain substances smell good even if they are not that healthy.”

“Previously, our emphasis was on testing separate materials and components,” Hanna says. Nowadays, a lot of this testing is done in approved third-party labs. Today, we test more and more in our chamber. If we get an unsatisfactory result in the chamber testing, we need to go further down the chain. Is it the laminate or the fabric that is the culprit? It's detective work.”

In another room, there are rows of glass bottles containing water and a piece of cut-out material. The bottles are heated to 40 °C (104 °F) for 24 hours before they are tested by the human nose.

“Our scent panel consists of four people each time,” Hanna says. “They cannot be smokers or wear perfume and should represent regular customers. During the test, everyone gives a grade according to a scale. The smell should not be too disturbing. Our sense of smell is incredibly sensitive and can detect scents that our measuring instruments don't pick up.”

Most materials arriving at Volvo Cars go through strict testing by our suppliers before they end up in our labs. New materials are constantly developed through environmental concerns or design trends. These new materials need to meet our high standards as well. Annelie tells us that she has tested everything from driftwood for decor to recycled plastic from the ocean. Not all materials make the cut.

What about developing new scents for our cars? In 1952, Julius Sämann invented the first air freshener for cars, encouraged by a milkman in New York, who suffered because the delivery van stank of milk. Sämann's blotting paper evolved into the car air freshener Wunderbaum. Today, many car brands work on adding an inviting scent to their vehicles.

“To add new substances is not desirable from a health standpoint and is not our ambition right now,” Hanna says. “How a car smells is a combination of all the materials in it– and it should be as pleasant as possible. But it’s not possible to make a scent-free car. Cars are complicated products. They are both a living room, a sound system, and a vehicle.

“We have strict control over the whole chain and work with solid materials that last over time. We want the customers to feel this quality when they get into their Volvo,” concludes Hanna.