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A Diesel vehicle has higher potential for CO2 reduction than a gasoline vehicle. However, it was difficult for the diesel vehicle to become a global CO2 reduction method, because the diesel vehicle cannot meet strict emission legislation such as LEV III legislation in US. Therefore, this research aims to reduce emissions of diesel vehicle to SULEV levels by using a Urea-selective-catalytic-reduction (Urea-SCR) system and unique engine and management controls. In order to achieve SULEV in FTP75 and US06 modes, both HC and NOx should be reduced during the warming-up phase of the Urea-SCR system, and extremely high NOx conversion efficiency after the warming-up phase is needed. The heat-up control using unique multiple injection and the early usage of exhaust gas recirculation (EGR) are applied to the warming-up phase. The dosing control using an NH3 sensor is newly introduced to increase the NOx conversion efficiency of the Urea-SCR system. When the air–fuel ratio combustion gas is kept at stoichiometric air–fuel ratio, a diesel oxidation catalyst (DOC) can indicate the same three-way conversion effect as a three-way catalyst (TWC) of a gasoline vehicle. The combination of the engine-out NOx reduction by massive EGR, the three-way conversion effect of the DOC and the NOx conversion effect of the Urea-SCR system is used during the warming-up phase in FTP75 and during acceleration phases in US06. This emission strategy was able to dramatically reduce NMHC and NOx emissions in FTP75 and in US06, and achieved the reduction in the emissions below LEV III SULEV category’s required levels.