One of most important issues in preserving the environment at the local level, mainly urban areas, is the level of CO, HC and NOx emissions. Emission standards exist for all three of these gases. Advances in engine control technology have enabled a reduction of CO, and the focus is now on the reduction of HC and NOx emissions. There has been discussion on the difficulty of reducing the level of HC and NOx emissions in direct-injection petrol engines, and thus the challenge in measuring up to increasingly strict global standards. However, Mitsubishi Motors realised at quite an early stage, that the GDI engine's unique basic technologies, which allow precise yet flexible control of combustion, could also be utilised to lower emissions of these two gases. An important point to consider in emission standards, is that priorities, driving modes and the quality of petrol vary drastically from region to region. We have thus focused on developing emission-reduction technologies that can be adapted flexibly and effectively to meet local requirements. These new technical features include: Two-Stage Combustion, a feature made possible by the GDI's precise control over the formation of the air/fuel mixture, a reactive-type exhaust manifold, which maximises this effect and; exhaust gas recirculation (EGR), which takes advantage of the engine's highly stable combustion; and a revamped Lean NOx catalyst. 1. Reducing HC Emissions In petrol engines, a highly effective Three-way catalyst is used to remove HC from exhaust emissions. The catalyst activates at temperatures above 250. Accordingly, it is necessary to warm up the catalyst immediately after the engine is started. This is made possible by a new combustion method we call Two-Stage Combustion, and a Reactive-type exhaust manifold, which increases the effectiveness of the process. The GDI engine operates in Stratified Combustion Mode when it is idling immediately after being started. Fuel is injected during the compression stroke, ensuring very lean operation. Combustion occurs toward the end of the compression stroke and concludes at the beginning of expansion, by which time the gases in the engine have risen to a high temperature. At this point, when fuel is injected again toward the end of expansion, the fuel injected into high-temperature atmospheric gas ignites, and the temperature of the operational gas rises, causing the mixture to ignite and burn a second time. As a consequence, the temperature of the gases rises as high as 800, compared to about 200 in the case of idling immediately after engine start-up.