Oct. 23 (Bloomberg) -- Toyota Motor Corp., the world's second-biggest automaker, and Mitsubishi Motors Corp. are using carbon fiber and aluminum in experimental vehicles as they develop lightweight cars with high gasoline mileage to win sales.

The 1/X concept hybrid car, which weighs 67 percent less than Toyota's Prius model because of a carbon-fiber body, will be unveiled at this week's Tokyo Motor Show. Mitsubishi Motors Corp. plans to introduce its i-MiEV Sport, an electric concept car with an aluminum suspension and frame that weighs 120 kilograms (265 pounds) less than if it were made with steel.

Crude oil has surged 42 percent to almost $86 a barrel this year, with U.S. gasoline prices reaching $3.23 a gallon. While sales of pickups and sport-utility vehicles tumbled, lighter vehicles helped Toyota gain customers in the U.S. at the expense of Ford Motor Co. and General Motors Corp., the largest carmaker.

``They are all trying to cut weight,'' said Edwin Merner, who oversees $2 billion as president of Atlantis Investment Research Corp. in Tokyo and owns stocks in car-parts makers. ``With gas prices getting higher, the carmakers are trying to improve mileage with lighter materials or thinner pieces of metal.''

Tokyo Show

Japanese carmakers use the Tokyo Motor Show to highlight technology that may find its way into production, the same way Toyota's 1995 vision of a gas-electric vehicle led to the 1997 Prius hybrid, the world's first commercially produced car that runs on electricity and gasoline.

Japanese automakers dominate fuel efficiency with hybrids. Toyota, Honda and Nissan make eight of the 10 vehicles with the best mileage, according to the U.S. government. That advantage has helped Japanese carmakers increase overall sales in the U.S. by 3.8 percent in the first nine months of the year, while sales at General Motors Corp., Ford Motor Co. and Chrysler LLC have dropped 7.9 percent. In the quarter ended June 30, Toyota earned 491 billion yen, 4.5 times more than GM.

GM sold 7.06 million vehicles through September, helped by the Chevrolet brand and the Opel Corsa small car, 10,000 more than Toyota, the two companies said in separate statements. In the quarter ended June 30, Toyota earned 491 billion yen ($4.3 billion), 4.5 times more than GM.

The biggest hurdle for the use of carbon fiber is the expense, according to Koji Endo, a senior analyst at Credit Suisse Securities (Japan) Ltd. He estimates the material would cost 100 times more to use in cars than steel. Toray Industries Inc., Japan's biggest carbon-fiber maker, will not give out the material's prices, said spokesman Yoshitaka Yamagata.

``Carbon fiber is a technology for the future, but it's going to take years of work before the carmakers can use it for mass production,'' Endo said.

A switch to the material from traditional metals would also mean significant redesigns of auto-assembly facilities and require companies to develop methods to recycle the material, said Honda spokesman Sage Marie.

`Sexy Concept'

``Carbon fiber is a sexy little concept that will reduce the weight, but it would be a very, very expensive proposition,'' said Vivek Vaidya, director at Frost & Sullivan Inc. in Singapore.

The carbon-fiber 1/X could travel 92 miles on a gallon of fuel, based on the Prius's rating of 46 miles a gallon. The 1/X uses half as much fuel as the Prius, Toyota said. The model runs on a blend of ethanol and gasoline and electricity.

Carbon Fiber

Carbon fiber, used in Boeing Co.'s 787 and Airbus SAS's A380 aircraft, is about four times stronger than the traditional material for airplane structures and weighs 40 percent less. Toyota currently only uses the material in Formula One racing.

Anticipating automakers' possible use of carbon fiber, Toray plans to spend about 20 billion yen ($175 million) to build a research center and a plant to make the material for cars.

Toray's sales of auto-related materials may rise almost threefold to 350 billion yen in the year ending March 2016 from 124 billion yen last business year, the company said.

``Toray's plan suggests using carbon fiber in car frames is getting more realistic,'' said Atsushi Kawai, a senior analyst at Mizuho Investors Securities Co. in Tokyo.

Other Candidates

Carmakers are also turning to aluminum, 33 percent lighter than steel. Mazda Motor Corp. will display a new rotary engine with aluminum substituted for steel in the side housings for the first time. The engine, to be introduced in the early 2010s, will be lighter and more powerful than the engine now used in the RX-8, the company said.

``Oil is getting scarcer and more expensive,'' said Seita Kanai, Mazda's head of research and development. ``That's forcing us to find ways to improve our cars.''

Efforts to cut cars' weight will play as great a role in new models as the development of hybrids and fuel-cell cars, said Ichiro Takamatsu, chief investment officer at Alphex Investments Co. in Tokyo.

``We will see more of lighter cars,'' said Takamatsu. ``That's the way to go for automakers to improve fuel economy.''

To contact the reporter on this story: Naoko Fujimura in Tokyo at nfujimura@bloomberg.net

Last Updated: October 22, 2007 19:02 EDT