Just how firm do today's car buyers want their seats? What do minivan shoppers really want in a seating fabric? How do we make an instrument panel that doesn't squeak? Are kids really comfortable in child-safety seats?

These are questions that once were asked--and answered--only by automakers. But now they sometimes are asking suppliers to take over this responsibility, too, especially for major interior components. Some automakers are delegating almost total responsibility to their suppliers for research, development and production.

"They used to tell us exactly what to do, they even gave us the prints," says Tom Russell, director of research at Automotive Industries, a major trim supplier in Rochester Hills, MI. "Now they tell us 'Here's kind of what we want, and you worry about all these new safety regulations.' It's gotten much more complex."

Mr. Russell says he isn't doing much research that is directly consumer-related yet, but that's not the case at Johnson Controls Inc. and Lear Seating Corp. Both have gained more design and development responsibility and are conducting extensive research on seat comfort and consumer tastes.

Seat comfort used to be determined by the "golden behind" of a high-ranking automaker executive who would plop down in a prototype late in the development cycle and give a thumbs up or a thumbs down.

Unfortunately, his (and it almost always was a middle-aged man) taste in seat comfort didn't always match the tastes of the vehicle's principal buyer demographic--which might be a young woman. Nevertheless, the "golden behind's" wishes usually were incorporated into the final seat, sometimes at great expense.

In the past several years, however, science has begun replacing this seat-of-the-pants approach. JCI, for instance, now purchases lists of vehicle owners and flies technicians around the country to conduct focus groups with an independent researcher on seating aesthetics and comfort. A special seat equipped with sensors and adjustable air bladders helps them develop sophisticated "comfort maps" for seats in various vehicle product categories. That helps them develop seats with just the right amount of support in the right areas for specific groups of vehicle owners.

The seats on the new Chrysler J/A Cirrus and Stratus cars are benefiting from some of this new comfort-mapping technology, but the full effects won't be felt for a few more model years. JCI emphasizes that not only does this customer focus make for better seats, but it can lower costs by eliminating expensive last-minute engineering changes.

Lear also conducts numerous customer clinics, including one recently with small children. The kids are taken on 30-minute jaunts, videotaped and asked just how comfortable they are in several types of child seats. Common complaints focus on too-tight lap belts, shoulder belts and crotch belts, and the inability to reach the toys on the back seat. Kicking legs and putting feet up on the front seats are signs of too much pressure on the back of the knees.

The study shows that kids want some freedom of movement, prefer automatic retractors, and some side support for resting weary little heads. "We must make the kids comfortable if we want them to be safe," Lear says. "They're telling us: "'Either give us comfort, or we'll make it tough on you. "'

JCI and Lear Seating also are working with dealers to create better products. Both suppliers have toll-free-800 phone numbers for immediate contact with customers or dealers who want to comment on their seats.

Suppliers of interior fabric also have their fingers on the pulse of consumers. For years they have studied the fashion and consumer apparel industries for trends in colors and textures, but they also routinely survey car buyers about their likes and dislikes. A survey of 300 consumers conducted four years ago by DuPont Co. showed that one of three car buyers changes car preference because of the color or type of fabric used inside the car.

Dick Giba, market manager of interior systems at the Automotive Materials Service Group of Dow Chemical Co., says earlier involvement in the development of interior products by suppliers enables engineers to attack and eliminate consumer complaints before they happen. Squeaks and rattles usually can be eliminated most efficiently at the initial design phase by using the "most correct" combinations of materials and material thicknesses, he says.