HONDA has developed technology to fulfill the strictest emissions standards to date. That is, we have developed the technology necessary to satisfy the state of California's SULEV (LEV–II) regulations. We were able to move from the conventional 600–cell, 4.3mil three–way catalyst to a 1200–cell, 2.0mil catalyst through the application of new canning technology. We were also able to achieve early catalyst light–off and improved conversion performance without increasing the precious metal content. However, it was not possible to satisfy the SULEV standards using only these improvements to the catalyst. It was also necessary for us to develop new emission control technology for the various stages of engine operation: cold, warm–up and post warm–up. Specifically, we developed technology that dramatically increases catalyst light–off speed by controlling intake air and ignition timing. Further, we developed technology to reduce exhaust emissions to the ultimate degree possible when the engine is cold and the catalyst is inactive. Also, in order to further improve the conversion performance of the catalyst once it is active, we developed a Secondary O2 Feedback Control System. This feedback system is an extremely high precision system that utilizes an adaptive sliding mode controller to identify various catalyst models in real time and predict the post–catalyst HEGO sensor output. The above technologies were used in combination to achieve the SULEV emissions standards.