But truthfully, Californians have weighed in on a variety of vehicles, including pickups and minivans, that nonresidents may never associate with their reputation.The list includes the Honda Odyssey minivan and the original Lexus LS 400 luxury car, which challenged German automakers' superiority when it was introduced in 1989.

The latest vehicle that Californians literally helped shape is the Nissan Titan pickup, the first really big truck from a Japanese company, which goes on sale late this year.In each case, Californians were guinea pigs for these companies, offering suggestions, acting as consultants for engineers and simply providing inspiration. They took part in focus groups and allowed engineers to examine their vehicles and videotape them while driving.Although these companies did research elsewhere in the United States, they relied heavily on California car buyers to act as stand-ins a good chunk of the time.
Certainly, California has always been a place for design inspiration. More than 15 auto companies have studios there, and the Art Center School of Design in Pasadena is a legendary training ground for young car designers. But fairly or not, Californians themselves have been viewed as far ahead of the rest of the country in their tastes.That actually can play to the car companies' advantage, because it takes three to four years for a vehicle to go through the development process.

Ideas that might seem on the fringe today could be considered conventional in 2007, auto analysts say.Californians' open-minded approach is what car companies appreciate when they are developing new vehicles, said Diane Allen, the chief designer of the Titan.''For a car manufacturer, it's a great laboratory,'' Ms. Allen said by telephone from San Diego, where she is based at Nissan Design Americas.

Three years ago, Ms. Allen and her team set out to learn what truck owners might want in a new pickup. One of their first admissions was that they did not know what they were doing. Nissan offered S.U.V.'s but the only pickups it had sold were little work trucks, which appealed primarily to surfers, or a limited market.''We decided to take our naïveté and put it out there in the truck world and educate ourselves,'' Ms. Allen said.

The Nissan designers interviewed dozens of California truck owners at the beach, in parking lots, at restaurants. But beyond that, they photographed them loading and unloading trucks, videotaped them behind the wheel and went off on jaunts with them.While the volunteers included ranchers and farmhands, Ms. Allen's team was also after people who used their trucks to transport ''toys'' like dirt bikes and all-terrain vehicles. The Titan team played host to evening seminars so truck owners could look at the designers' ideas and offer feedback on various parts of the truck.The suggestions led to an important Titan feature: anchors in every corner and on each side, so that gear could be tied down tightly.

Numerous truck owners showed the Titan designers how they had drilled holes and screwed in hooks so they could secure equipment with bungee cords, she said.With imports comprising more than 50 percent of car sales in the state, Ms. Allen said Californians were not reluctant to help designers from a Japanese company. ''For us at a global company, Californians are much friendlier than a state like Wyoming or Idaho,'' she said.The biggest problem, she said, was that the truck owners did not want to go home. ''We couldn't get them to leave,'' she said.''They would be here three or four hours.

''A group of Toyota designers from Japan stayed far longer than that. In the early 1980's, Toyota's chief executive, Eji Toyoda, vowed to build the finest luxury car in the world. And he wanted to sell it in the United States, not Japan. That vow led to development of the original Lexus LS 400 sedan. But the project was a big secret for almost everyone in Toyota.They included six designers from Japan, who checked into a house in Laguna Beach, Calif. Their arrival was an extraordinary step for Toyota, whose previous car development had all happened overseas.

''The fact that they came to Southern California is important, but even more important is that they came at all,'' said J. Davis Illingworth, a senior vice president at Toyota Motor Sales USA, the company's American sales arm.Mr. Illingworth was then second in charge of what became the Lexus luxury car division. He ultimately served as the division's first general manager. The six designers spent time soaking up both the sun and Californians' preferences in luxury cars. Over 18 months, they sent back a half-dozen versions of the design for the Lexus LS 400, finally hitting on a car that echoed German luxury models, but with a softer appearance to appeal to American buyers.''They were really good listeners,'' Mr. Illingworth said. ''Had they not come, we could have ended up'' with a luxury car that looked more like those sold in Japan.

Closeness to the customer was also the aim of the engineering team that worked on the latest version of the Honda Odyssey minivan, which went on sale in 1998. The previous version of the Odyssey was a small van with a four-cylinder engine and doors that opened out from each side as on a car. It was nothing like the hottest American vans then on the market, which were bigger, more powerful and had sliding doors on each side.

Eager to hit the mark, the project's chief engineer, Kunimichi Odagaki, came to the United States from Japan to oversee development. Accompanied by a pair of American engineers, Mr. Odagaki spent six months traveling 25,000 miles around the United States, visiting communities across the Midwest and the South.Eventually, the trio ended up in Orange County, Calif., where they adopted the elementary school attended by the daughter of one engineer, Tim Benner. They tapped into ideas from the children's parents, including one suggestion that the Odyssey have leaner lines than the rounder Mommymobiles in vogue then. They also measured the width of Mr. Benner's garage, to make sure the minivan would fit.

And they learned on highway on-ramps, facing heavy traffic, that it was important to have a six-cylinder engine with plenty of pickup.The three encountered a few scrapes. One afternoon, as they sat in the school's parking lot, videotaping parents loading their kids and assorted gear into their vehicles, a policeman rapped on their window. ''He thought we were going to kidnap the children,'' Mr. Odagaki recalled last year.But the engineers eventually became celebrities at the school, and the Odyssey minivan became a big hit. It is now the second-best-selling minivan in the United States, behind the perennial leader, the Dodge Caravan.

Until recently, the Odyssey was ranked as the best minivan in the country by Consumer Reports magazine, a crown it has since yielded to the Sienna Toyota.The vehicles are proof that Californians, despite their reputation, give companies good advice, said Art Spinella, the director of CNW Marketing Research, an auto-industry firm in Bandon, Ore.

''Regardless of what everyone thinks, Californians don't set new trends,'' Mr. Spinella said. ''But they identify new trends'' and help make them popular, he said.Mr. Illingworth added: ''There's a certain amount of freshness or newness or difference about California'' compared with the car capitals of America and Japan. ''Your view of the world is different in Los Angeles than it is in Detroit or Toyota City.''