A schematic diagram of a transport hybrid power plant using a new design RPE-4.4/1.75 rotary piston air engine is proposed. Its external speed characteristic is determined, according to which the maximum engine power is 8.75 kW at 850 rpm and the maximum torque is 127.54 N∙m at 400 rpm. For various gears and speeds, all the components of the power balance were determined and the dynamic characteristic of the hybrid car was obtained when operated on an air engine. According to the dependences of the power balance, the total traction force from the rotary piston air engine on the driving wheels is 5 kN. The performance of acceleration of a hybrid car while working on an air engine is estimated, namely, the dependences of acceleration, time,and acceleration path are obtained. In urban traffic, the required time to accelerate the car to a speed of 60 km/h is 15.2 s and the path is 173 m. The possible drive range of the hybrid car on compressed air without additional recharging is analyzed. On one cylinder with compressed air with a volume of 100 liters, an initial pressure of 35 MPa, and a final pressure of 2 MPa, the hybrid car can travel about 26 km.