Abstract. Objective: To study the technology of auxiliary motor starting and stopping of the direct injection gasoline engine, and analyze the effect of the idle start stop system and oil saving energy. Method: the fuel saving effect analysis of the fuel saving effect of the system is analyzed by the multiple model. Process: we in the downtown and suburban stop system to open and close the NEDC fuel consumption record results, typical conditions stop system NEDC drive cycle fuel saving effect curve analysis, and instantaneous fuel consumption curve comprehensive comparative analysis. Conclusion: through data analysis, we can know that the average vehicle parking time is more than 9S, the system can reduce the fuel consumption of vehicles; for these two models, starting fuel consumption is high.