Abstract
Reducing emissions and fuel consumption for vehicles is a hot issue, attracting the attention of researchers. One of the solutions to achieve this goal is to use a hybrid powertrain. This paper will research and manufacture a synchronous hybrid system with a stepless transmission system installed on the vehicle. Research results show that the internal combustion engine will always work stably at the optimal mode when the external load changes. Thereby, the fuel consumption rate and emissions of the vehicle will be reduced. The result of this paper is a significant contribution in the process of designing and developing hybrid vehicles in Vietnam.