Japanese auto giant Toyota Motor Corp. showcased a new hybrid concept model that is packaged in carbon fiber to reduce weight, fuel consumption and emissions. The four-seater "1/X", with a 500-cc engine, boasts a potential fuel efficiency twice that of the Prius, Toyota's popular hybrid vehicle. At the industry show held in suburban Tokyo, automakers highlighted environmental technologies amid rising gas prices and increasing public awareness about climate change. The concept vehicle's name reflects the automaker's aim to improve energy efficiency and to cut weight by unspecified "x" times. The concept model weighs 420 kilograms (925 pounds), roughly one-third of the Prius. The model also carries a plug-in hybrid system, which uses both electricity and fossil fuels. Despite its strength and light weight, carbon fiber's high cost has so far limited its use in mass produced automobiles.