If one can deduce directly from concept cars displayed at September's Frankfurt auto show, interiors of the future will have Universal Serial Bus (USB) ports to transfer all sorts of personal information and music.

The Paris show a year ago had only two concept cars that were not stalking horses for a forthcoming product, but the Frankfurt auto show featured a number of “traditional” concept cars, those that express new ideas and seek a reaction from the public and press. And where more than one set of future-thinking designers comes up with the same idea, a potential trend is born.

In Frankfurt, concept interior trends beyond memory sticks and USB ports included treating passengers more individually, modular rear seats for one or two occupants and Neoprene as an interior material.

Designers of the Smart Crosstown, Mazda Sassou and Ford Iosis were among those who chose to imagine interiors that will conform to the user's preselected criteria when he or she inserts a USB key-stick into the dashboard.

While the idea has been shown before, associated with everything from key fobs to fingerprint readers, this year, imagination was directed toward the ubiquitous USB “stick” or i-Pod MP3 player carried by almost everyone under 30.

“We have a stick for each seat,” says Ford designer Ernst Reim. Passengers will have seat adjustments, climate control and even DVDs loaded in theirs, and the driver's stick could include navigation, everything the car needs to know, and music.

In the Crosstown, Smart's Jeep-like 2-seater hybrid concept, the USB sticks are designed to look like the music they carry — Mozart's bust for classics, a rapper for hip-hop — and a removable personal digital assistant (PDA) will handle navigation and other driver tasks.

“A young guy won't pay €2,000 ($2,430) for integrated navigation,” says Hartmut Sinkwitz, until recently chief designer for Smart and now head of Mercedes-Benz AG's advanced design studio.

Mazda plugs a USB stick into the Sassou's joystick, which serves like BMW AG's i-Drive to reduce the number of buttons and knobs. The stick carries music and navigation information, and LEDs send a trail of light toward the function that is currently active, such as the navigation screen or the air conditioner.

“We call it veins, like blood going from the brain to the function,” says designer Michael Loyer. “Visual information is better for driving than words on a screen.”

The addition of a USB port is a sign of the future if the Autosar project in Germany finally results in standards for electronic interfaces in the car, and if it acknowledges the reality of consumer electronics: people carry their own electronics around.

“Our car is for the generation that grew up with Playstations,” says Ford's Reim, reflecting a thought of Johnson Control Inc.'s European design chief, Han Hendriks.

Young people who grew up with the Internet, i-Pods and portable telephones, will be buying their first new cars in the middle of the next decade, says Hendriks. “They have their technology with them. There is no way they will pay for an integrated telephone or navigation system.”

Interiors are important in Europe, and they are changing.

“Five years ago, I would have said that the exterior was 80% of the buying decision, and the interior 20%,” says Emmanuel Aouad, Renault SA's marketing director for France. “Now it is maybe 60-40, and I think it will go to 50-50. The interior was always important for women, and it is starting to be for everyone.”

In general, the interiors of the concept cars on display at the Frankfurt show paid more individual attention to passengers.

The Toyota Endo design began with the interior, says its designer, Laurent Bouzige, of the Toyota Europe Design Development in Nice, France. It features hard plastic surfaces, thin shaped seats, clear lines and a pearl- white interior. Like the Mazda Sassou, it has a rear seat that converts to accomodate two passengers or one.

In the Toyota, half the rear seat turns into a table when it is not being used. In the Sassou, the bench seat has hidden air cushions inside. One rear seat passenger would sit in the more sociable middle position, where he can see out the front and participate in conversations with both front seat occupants. Bolsters would push out of the seat back at his sides. If there are two seated in the rear, the bolsters would be in the normal places. “Our first goal was to target young buyers, connect to their needs and their high-tech skills,” says Sassou designer Michael Loyer.

The Sassou front seats look as if they are linked together, but each seat moves forward and backward independently, the armrest moving with the driver.

The Citroen C-Sportlounge concept took the same idea for front seats a step further: Half the common console between the two seats moves with the passenger's seat. “Passengers are as important as the driver, so each is treated at the same level,” says designer Mark Lloyd.

The Ford Iosis and the Skoda Yeti concept used Neoprene, the rubbery stuff used for the suits scuba divers wear, as a new interior material.

“Neoprene is good because it stretches in all directions,” says Reim. “You can treat it like you treat leather, and it can have powerful colors.” It has so many good properties that Ford now is testing it for durability, says Reim.

Designers are always looking for the right material. For Skoda's Yeti convertible, head designer Thomas Ingenlath says rubber was chosen to cover the instrument panel for easy cleaning.

“Color and trim details are not in conventional materials, the conventional perception of natural material,” he says.

“We took inspiration from the sport and leisure wear sector, where people wear many synthetics now. They know synthetic materials are good for the skin, comfortable, and easy to clean, but it will take time to convince people to accept them in production.

“A cabriolet (interior) gets dirty inside very easily,” Ingenlath adds. “This can be kept clean with a sponge or a wet cloth, far easier than with leather in a classic cabriolet.”

While cars like the European-designed Toyota Endo and Mazda Sassou featured Spartan plastic-like interiors, it hardly seems likely that wood and leather ever will go away.

The Smart Crosstown concept contrasted its unpainted plastic interior trim with worn leather featuring designs burned in with a laser, and the Citroen C-Sportlounge had a plush leather interior.

“We live in a world with a lot of synthetic things. Everything is coming and going faster: fashions, electronics, everything,” says Volkswagen chief designer Murat Guenak, who introduced the new Volkswagen Eos coupe-cabriolet with its leather and wood interior.

“Customers for luxury goods are looking for value, and one guarantee for value is natural material like leather and wood. The cliché thinking behind this is that it represents craftsmanship by hand.”

However, he admits, in the long term things may change because “there is a banalization of luxury material. Twenty years ago, you saw leather and wood only in a Bentley or a Mercedes, and now it is in many cars.”