The invention provides a car energy-saving power device. The car energy-saving power device comprises an air energy-saving power device used for reducing work applying of a car engine, and a wind energy-saving power device used for reducing output of a car storage battery. The air energy-saving power device comprises a first control device, a wind inlet pipe, a piston-type compressor, a check valve, an exhaust silencer, two aftercoolers, an exhaust main pipeline and an air storage tank. The output end of the air storage tank is connected with a car air cylinder pipe through a first solenoid valve. The wind energy-saving power device comprises a second control device, a wind turbine, a permanent magnet synchronous generator and a foldable-type support. The output end of the second control device is electrically connected with the car storage battery. According to the car energy-saving power device, the structure is simple, car fuel is replaced through match use of the piston-type compressor and the air storage tank to drive a car to start and accelerate, and energy conservation and environmental friendliness are achieved; and through control of the second control device over the wind turbine and the permanent magnet synchronous generator, power is supplied to the car storage battery at any moment, and the situation that the power of the storage battery runs out, and thus car travelling is influenced is avoided.