By 2015, Toyota plans to roll out cars in which bioplastic accounts for one-fifth of all plastic components. Masatoshi Matsuda, Toyota senior staff engineer, announced the goal at the BioJapan 2008 conference this month, according to news site Tech-On.

Toyota established a biotechnology unit in 1998, originally sourcing bioplastic based on sweet potatoes and eventually building its own production plant for making polylactic acid, a bioplastic that can be derived from corn, sugar cane and other plants.

The company first displayed how bioplastic can be used in vehicles with its 2001 ES3 concept car. Two years later it made bioplastic parts a reality, manufacturing the spare tire cover (shown in the above photo) and floor mats of the Raum out of bioplastic. Also in 2003, Toyota offered optional floor mats made of bioplastic for the Prius.

Toyota has also used fibers from the kenaf plant to make sections of trim for the Lexus LS460 and Corolla Axio in 2006.

In announcing the company's 2015 goal of having bioplastic make up 20 percent of plastic parts, Matsuda touched on why Toyota has used bioplastic in limited applications. "We are not ready to use more bioplastics in view of the balance between the cost and the performances such as properties and formability," he said, according to Tech-On. The company is investigating how to tackle some of the problems in developing bioplastic that performs as well as regular plastic, such as improving heat resistance, formability, shock resistance and long-term reliability.