A quarter of all "eco cars" will use carbon fiber within six years as automakers ranging from General Motors to Toyota turn to lighter materials to improve fuel economy, an Osaka-based supplier says.

Teijin Ltd., provider of carbon fiber to Airbus Group NV's A380 superjumbo, forecasts industry sales of carbon fiber cars will reach 3 million units by 2020 as it works with U.S.-based GM to develop the material for mass production, according to a statement Friday.

Carbon fiber — about 10 times stronger and 75 percent lighter than steel — has so far been used only in sports cars and luxury vehicles such as Toyota's Lexus LFA and Volkswagen's Lamborghini.