Development of low-pollution diesel engines is heating up among truck manufacturers in Japan. Following this years long-term controls on exhaust gas will be short-term controls to begin in 2002. Controls are to be tightened in rapid succession, with already determined targets for reducing exhaust gas and a new set of long-term controls to begin by 2007. As profits fall for truck manufacturers during the auto slump, research and producton departments are being asked to combine wit with speed to meet these controls and improve fuel efficiency.