The performance and durability of Diesel-type methanol vehicles have been investigated based on a controlled fleet test utilizing five heavy-duty Diesel-type methanol buses each covering a cumulative distance of some 100,000 km, and on a subsequent teardown of engine parts. Developmental research has also been carried out covering the advanced methanol combustion technology aimed at lower pollution potential and high efficiency, as well as an exhaust gas treatment system based on a NOx reducing ("DeNOx") catalyst. The resultant achievements can be summarized as follows: Since the results of the controlled fleet test indicated that the technical problems for the Diesel-type methanol vehicles were low durability and reliability of components in the ignition or fuel systems, interval for replacing these components was determined. It was then demonstrated that a regular renewal of related engine parts should ensure that the methanol vehicles perform satisfactorily in actual application. Concerning the advanced methanol combustion technology, it has been determined that auto-ignition combustion of a lean premixture of methanol ("Methanol lean burn system using an auto-ignition") will enable a substantial reduction in NOx emission compared with existing diesel engines operating on the same energy consumption basis at middle to low load conditions. In research on the exhaust gas treatment system based on a DeNOx catalyst, a catalytic NOx reduction system utilizing unburned methanol in exhaust gas as a reducing agent has been developed. The exhaust gas treatment system has demonstrated a capability of reducing the NOx emission level to approximately one-half of Japan's long term standards (1999's regulation) for diesel exhaust emissions.
