Kobe Steel Ltd., supplier of aluminum sheet to half of the nation's auto industry, is considering building a ¥100 billion plant in the U.S. to expand sales to Japanese carmakers operating in North America.

The prize is an expected tenfold increase in demand for aluminum sheet in the U.S., where stricter fuel economy standards have ignited a race among carmakers to save weight and boost the efficiency of new models, driving up demand for the lightweight metal.

The size of Kobe Steel's potential investment is larger than anticipated because the company may need to add capacity at the plant to process aluminum alloy, Senior Officer Hiroshi Kato said last week in an interview at the company's Tokyo offices.