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May 14, 2000
Ah, the Aroma of a Just-Baked Sedan
SMELL is a fickle sense. And when a fickle sense can make or break a $25,000 purchase, it's enough to merit serious attention. By TIM MORAN
It's the kind of attention that prompted Volkswagen to add odor-control programs in the production of its New Beetle and latest Golf, and the drive that led Ford to unleash a $75,000 "electronic nose" to analyze parts for its Focus compact car.
The automakers know that customers like the "new car smell," a cocktail of volatile organic compounds that swirls from the rubber, leather, cloth, plastic, wood and chemicals used to assemble a car. So the companies are not trying to get rid of new-car smell. They want to control it, first, and understand it so they can limit the number of bad smells that are part of the mix.
In the future, smell specialists say, carmakers may even be able to insert specific smells to help sell a vehicle or improve the driver's experience. Scents like cucumber or green apple, in very light doses, can ease claustrophobia. Other smells can invoke a positive mood or modify hormonal releases.
The real new-car smell dissipates fairly quickly. After two to three months of driving, air flow through the car has carried away most of the chemicals responsible.
It seems like a small amount of time to worry about, but smell is one of the most powerful human senses, and some smells effectively set themselves in memory. It's easy for an owner to decide that a hatchback is bad simply because he or she doesn't like its smell -- and enough residual smell is always left to remind them.
So some car makers are manipulating the new-car smell, or the smell of materials in the car. In the early 1990's, General Motors asked a supplier to add a fragrance to a type of leather, for example, because the tanning process left its smell too muted.
But automakers acknowledge that they have to be careful, because nobody is sure exactly what makes a smell successful. There are too many variables among the thousands of materials and potential combinations, and among the buyers themselves.
The human nose has more than 20 million receptors for smell. Each person has a different sensitivity, though women are generally more sensitive to odors than men.
And as buyers age, their sense of smell diminishes. Many customers say new cars don't smell as good as they used to. It's a very short step from that to the idea that cars smell worse these days.
"They like the idea of the smell of a new car," said Dr. Alan Hirsch, neurological director of the Smell and Taste Treatment and Research Foundation in Chicago. "They like the leather and plastic smell. Part of that has to do with olfactory-evoked nostalgia. The smell of new cars makes them recall having a new car when they were little, or when they were in childhood, and that evokes a very positive mood state.
"There are many products that have sort of 'signature' scents, smells that make you identify the product, Dr. Hirsch said. "Play-doh is one, or Welch's Grape Juice -- or new cars. It makes ultimate sense to intensify these artificial smells, because people attribute a positive quality to them."
The Ford Motor Company has not tried to intensify the new-car smell, but it has worked to isolate each component that goes into a car to make sure it doesn't detract from the overall aroma, said Dr. Jorg Sassmannshausen, who heads the Analytical Section of Central Laboratories in Germany. There, in a suburb of Cologne, appropriately, Ford tests product samples with both a panel of human evaluators and with the E-nose 4000, a smell-analyzing computer.
The smell crew takes whiffs of air from fruit-canning jars that contain a chunk of car material and a little water, and which are held at 108 degrees Fahrenheit for 16 hours. That's enough time to get the maximum amount of smell out of the product in the humid, smell-carrying conditions of a car parked in tropical sun. The Ford sniffers rate the components from 1 to 4, with 4 being "disgusting, obnoxious." Ford accepts only materials rated 2 or lower.
"It's very hard to make an evaluation of the complete car," Dr. Sassmannshausen said. "We try to minimize the smell of every single component. Of all the components -- the carpet, seats, textiles, door panels -- if they fulfill this requirement, as a symbiosis of all this, we have a new-car smell the customer expects."
Only the human sniffers can tell whether an odor is pleasant, unpleasant, weak or overpowering. Once they've set their measurement, the computer nose can be programmed to recognize the chemical "signature" of a material's smell.
Then the E-nose can be used as a production tool, measuring a sample of components as they come in to make sure they're continuing to meet smell targets. The process can go two ways; Ford has found that smell helps it to analyze manufacturing problems at the suppliers.
Some of the toughest smells come from foams and caulklike mastics used to deaden sound and to pad areas like the floor. If the manufacturing process doesn't completely cure some plastics, for instance, a series of cars can suddenly turn into stinkers. That is because the uncured plastic can decompose over time, hydrolizing, producing byproducts that smell rancid to humans.
Rubber is another problem. "If they are using, let's say, cheap curing systems or bad process parameters, then you have a fishy smell coming from door seals and window seals," Dr. Sassmannshausen said.
With more and more materials in cars, manufacturers have had to be careful about the smells they carry. Amine-containing compounds, which incorporate nitrogen, can smell like urine.
Thiol-containing compounds -- the main flavor of grapefruit is from due to thiols -- are very unpleasant to humans at high concentrations. Sulfur-bearing compounds can emit strong, repulsive odors -- like the smell of old broccoli or cabbage -- as they break down.
Frank Marcus, technical director for Car and Driver Magazine, said he thought that most cars were getting less smelly over time. "I have noticed that every Korean car has an odd sort of vanilla smell about their plastics," he says. "Hyundais always smell a certain way, and obviously the cars with genuine leather interiors, the kind where you can point to where on the cow it came from, will have nice smells in them."
At Hyundai Motor America, Mike Anson said the company had not specifically analyzed smells. That's not unusual; a spokeswoman said G.M. hadn't conducted formal odor research recently.
A DaimlerChrysler spokesman said the subject wasn't under discussion at the company.
Almost nothing manufacturers can do comes close to the mistakes that drivers make. Mr. Marcus's most memorable smell experience with a test car occurred after a driver left a tuna sandwich under the seat for several days in hot weather.
"It never came out," he said of the odor. "The smell was right down into the metal."
Dr. Stuart Firestein, a research scientist and associate professor at Columbia University, said rotting meat or spoiled milk were long-lasting problems, perhaps because of the bacteria that feast on them, and were tough to eradicate.
At Ford, Dr. Sassmannshausen said the owner could wipe out the most careful work of an auto company with just a quick squirt of the fragrance chemicals sold in auto-supply stores. "I have to say if somebody uses 'new car smell' or 'green apple' or whatever, all our work is for nothing," he said.
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