This study reports on a new generation ECS (Ejector Cycle System) which includes a highly efficient ejector and a novel system configuration. The ejector is working as a fluid jet pump that recovers expansion energy which is wasted in the conventional refrigeration cycle decompression process, and converts the recovered expansion energy into pressure energy and raises the compressor suction pressure. Consequently, the ejector system can reduce power consumption of the compressor by using the above mentioned pressure-rising effect and improve energy efficiency of the refrigeration cycle. The ejector consists of a nozzle, a suction section, a mixing section and a diffuser. The objective of this study is to improve actual fuel economy of all vehicles by ejector technology. The previous generation ECS was reported in 2012 SAE World Congress1. Now, a new generation ECS has been successfully developed and released in the market for Mobile Air Conditioning systems as of 2013. It achieves higher energy efficiency through the development of ARC (Active flow Ratio Control. It means to control the refrigerant flow ratio of the suction flow to the total flow by separating gas-liquid two phase flow), improved design of each ejector part, and improved internal flow distribution inside the evaporator. The ejector is integrated into the tank of evaporator like the previous generation, so there is no impact to vehicle packaging space. Test results demonstrated that the new generation ECS reduced annual power consumption of compressor by 10% compared to previous generation and by 20% compared to conventional expansion valve systems. The new generation ejector technology can significantly improve actual fuel consumption of Mobile Air Conditioning systems and contribute to global greenhouse gas reduction.