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This paper discusses the development of a new approach to achieving EURO 4 emission standards with a simplified exhaust after-treatment system in combination with an air-assisted lean stratified Direct Injection system. The results presented demonstrate the ability of the air-assist DI system to operate in highly stratified conditions at very lean A/F ratios, with excellent control of the raw HC and NOx emissions. In most cases the authors illustrate that with good stratified combustion control, the HC emissions can be lower than the baseline port injected stoichiometric engine. Further, the high tolerance to EGR and accurate A/F control at the spark plug enable the raw NOx emissions to be reduced by up to 85% over the European drive cycle in comparison to the baseline port injected engine with EGR.