Since thelatter half of the s, global warming has been a prominent issue ininternational politics. The Japanese government has announced itsaction plan for mitigation of global warming and many implementationprogrammes are arising in each domestic sector. Above all, measures areurgently needed for reducing CO emissions in the automotive transportation sector. This sector accounts for about % of the nationâ??s total CO emissions, which are increasing continuously.The study reported here has three aims: simulating the amount of COemissions from Japanâ??s automotive sector for  years from now;evaluating the potential of automotive technologies for reducing themto the level; and considering the possibilities of implementingthese measures. This paper consists of four parts. In the secondsection, technological scenarios are presented; then the effects of COmitigation are evaluated, following which the market penetration ofadvanced technologies is evaluated, calculating the life-cycle costi.e. purchase price plus operating cost of the technologies in thelight of estimated energy prices. The final section presents a summaryand discussion of the implementation of the effective scenarios.. Automotive technologies for reducing CO emissionsThesecan be grouped into two categories: improvement of fuel consumption inconventional vehicles, and the introduction of alternative-energyvehicles.