Abstract Lexus developed the Multi Stage Hybrid Transmission for the flagship Lexus LC500h coupe with the aim of achieving an excellent balance between fuel economy and acceleration performance. To gain these benefits, this transmission utilizes a multi-stage approach with the input split mode as an enabler for a concept of multiple high- efficiency points. In order to apply this approach to the transmission, a shift device was located immediately after a power split device. For functioning of the input split mode electrically-controlled continuously variable transmission, the power split device is connected with the motor, generator, and inverters. The optimal gear selection of the shift device to reduce the power loss in accordance with the driving state improves not only fuel economy but also heat management performance compared with the previous hybrid transmission. The Lower gears of the shift device that amplifies both the motor and the engine torque enhances acceleration performance compared with the previous hybrid transmission which amplifies only the motor torque. This paper describes the motivation for selecting the multi-stage approach with the input split mode from implementations of multiple high-efficiency points concept, and the potential of multi-stage approach with the input split mode compared to the previous hybrid transmission. 1. Introduction In 2006, Lexus launched the Lexus GS450h installed with the Lexus Hybrid Drive (LHD) system that developed for rear-wheel drive (RWD) passenger vehicles [ 1]. The system was also adopted for the all-wheel drive Lexus LS600h in 2007. The system includes the hybrid transmission which is equipped with a two-stage motor speed reduction device [ 2].The acceleration performance of the previous hybrid transmission is highly regarded even by drivers of competing vehicles, while also providing superior fuel economy. Since the launch of these vehicles, various refinements have been applied to the previous hybrid transmission, which has already made a major contribution to reducing CO 2 emissions.However in recent years, heightening awareness of environmental issues have created growing demand for all types of environmentally friendly vehicles. In combination with this trend, countries and regions around the world have announced plans to introduce even more stringent emissions regulations. For these reasons, it is important to develop and popularize vehicles with even higher environmental performance than before. Consequently, as automakers around the world actively develop environmentally friendly vehicles, a wide range of systems have been launched and competition in the market is growing more severe. Even in the luxury coupe market, which is dominated by vehicles with excellent dynamic performance, hybridization is increasing and even higher levels of fuel economy and acceleration are required. With this background, the Multi Stage Hybrid System was developed to achieve a superior balance between fuel economy and acceleration performance in the RWD coupe market. The LC500h,which combines this system with a V6 engine achieves a 0-to-60 mph time of 4.7 seconds , 30.0 mpg of combined fuel economy and SULEV requirement for the exhaust emission. The newly-developed Multi Stage Hybrid Transmission (Fig.1) significantly contributes these performances. Figure 1. Transmission cross-section.Concept and Approach of Multi Stage Hybrid Transmission 2017-01-1098 Published 03/28/2017 Tatsuya Imamura, Atsushi Tabata, Tooru Matsubara, Yuji Iwase, Kenta Kumazaki, and Keita Imai Toyota Motor Corporation CITATION: Imamura, T., Tabata, A., Matsubara, T., Iwase, Y . et al., "Concept and Approach of Multi Stage Hybrid Transmission," SAE Technical Paper 2017-01-1098, 2017, doi:10.4271/2017-01-1098. Copyright © 2017 SAE International2. Development Objectives The objectives of the development of this new hybrid transmission for large-displacement engine RWD HVs w