The rapid economic growth in ASEAN countries has created a major air pollution problem in the region. Moreover, it has become desirable for ASEAN countries to integrate markets to increase the international competitiveness of their automobile producers. Therefore, a main topic is now to enhance the mutual complementarily for parts procurement by reducing customs duties in the region and harmonizing safety and technological standards. At the AMEICC Working Group held in Cambodia in May 2004, it was agreed to set target for introducing EURO2 at least by the end of 2005 and EURO4 by the end of 2010. At the same time, there was consensus regarding the necessity to take immediate action to improve fuel properties toward the target of emission gas regulations, and an action plan was adopted to improve properties with a target year of 2010.