1. Abstract As the demand for so-called eco-cars has been increasing recently, new hybrid transaxle P610 has been developed to achieve outstanding fuel economy and an excellent driving performance. P610 was installed in the 4th generation Prius, the first car to implement TOYOTA's new development strategy, TNGA (Toyota New Global Architecture). In order to accomplish the goal, radical reduction of mechanical loss, size and weight, dual-axle motor structure are adopted to draw out the potential capability of the THS (Toyota Hybrid System) to the maximum extent possible. Furthermore, placing the compact power train low, which is realized by installed the PCU(Power Control Unit) on top of the transaxle, led to provide the low center of gravity of the vehicle and excellent driving performance. 2. Introduction Since the world's first mass production hybrid system was developed and installed in the 1st generation Prius in 1997[ 1,2,3], increased environmental awareness led to raise the demands for the vehicle to have superior fuel efficiency and cleaner exhaust gases. As the eco-cars become popular, the customer's needs for various performances except for fuel efficiency, such as driving performance and styling, has been increasing. And the automakers need to put together the various performances in a high level. Then TOYOTA implements the new development strategy, TNGA, to the new generation Prius. This paper describes the main features and performances of the newly developed hybrid transaxle P610 for compact vehicles which is installed in the new Prius. 3. Develompment Objectives The development goal for P610 is (1) reducing the overall length of the transaxle to fit in the new platform, (2) reducing the weight and low mechanical loss to contribute to fuel economy and (3) improving the NV ( Noise and Vibration ) performance to keep the vehicle quiet.4. Basic Specifications and Structure Figure 1 and 2 show the main cross section and schematic diagram of P610. Table 1 details its major specifications. P610 consists of a 4 axle structure of torsional damper with a torque limiter, input shaft, planetary gear for torque split, generator, motor, reduction device, differential device. The planetary gear functions as a power split device that divides the engine power into the driving power for the vehicle and the generator. The motor is positioned on a separate axle from the engine, as the motor reduction device, the parallel shaft gear, is adopted. The counter driven gear receives power from both the engine and motor, and transmits their powers to the differential gear. Table 1. Specifications of new hybrid transaxle Development of New Hybrid Transaxle for Compact-Class Vehicles2016-01-1163 Published 04/05/2016 Makoto Taniguchi, Takahisa Yashiro, Keiji Takizawa, Shinichi Baba, Michitaka Tsuchida, Tatsuhiko Mizutani, Hiroatsu Endo, and Hiromichi Kimura Toyota Motor Corporation CITATION: Taniguchi, M., Yashiro, T., Takizawa, K., Baba, S. et al., "Development of New Hybrid Transaxle for Compact-Class Vehicles," SAE Technical Paper 2016-01-1163, 2016, doi:10.4271/2016-01-1163. Copyright © 2016 SAE International Figure 1. P610 cross section Figure 2. Schematic of new hybrid transaxle 5. Compactness and Weight Reduction Figure 3. Comparison of size between P610 and P410Based on the adoption of the new gear train, new motor and a dual-axle motor structure, P610 accomplished the compactness and weight reduction although P610 has similar torque capacity from the former P410. The overall length of P610 is much shorter than the former P410 by 47mm and the number of component parts and weight are also reduced by 20% and 6.3 % respectively. Details of reduction size and weight technology are introduced below. 5-1. PCU Installation As shown in Figure 4, the PCU is installed on top of the transaxle in order to keep the powertrain compact. This allowed the auxiliary battery, which was in the luggage area for the former P