Secret to Toyota's fuel efficiency: Hybrid Synergy Drive

September 30th 2016 | Benjamin Yong
Toyota's Hybrid Synergy Driver technology powers each one of the company's hybrid vehicles.


We all know the Toyota Prius family of vehicles are fuel-efficient. Some may even know it’s because of the automaker’s Hybrid Synergy Drive (HSD) system that powers every hybrid model. But how does it work? Find out below.

At the core of HSD is a twin motor-engine setup. A gasoline engine acts as the primary means of propulsion and an electric motor provides backup power and recovers surplus energy. The computer automatically switches between the two to deliver maximum fuel efficiency and a comfortable driving feel.

Toyota Hybrid Synergy Drive startup

Let’s dive a little deeper into the technology. When the vehicle is initially started up and all the way up to the mid-speed range, engine efficiency is at its poorest. As a result, the gasoline powerplant is shut off and the car runs solely off the high-output electric motor.

Toyota Hybrid Synergy Drive normal cruising

During normal cruising, the main power switches over to the warmed up engine running at high efficiency, which directly drives the wheels. A generator is also engaged — via a built-in device that splits and diverts engine output — to produce electricity for the motor.

Toyota Hybrid Synergy Drive acceleration

In scenarios calling for rapid acceleration like passing on the highway, power is supplied simultaneously from both sources to boost performance.

Toyota Hybrid Synergy Drive braking

As soon as it’s time to slow down, the process happens in reverse. While the driver lets off the accelerator and/or gets on the brakes, the wheels turn the motor, now operating as a generator, converting rotational and braking energy into additional electricity used to charge a high capacity battery. This is known as regenerative braking.

Toyota Hybrid Synergy Drive battery recharging

When the battery level dips down to a low level, the engine switches on the generator to begin the recharge cycle, ensuring the system maintains a healthy charge for optimum operation.

About the Author

Benjamin Yong is a freelance journalist and communications professional living in Richmond, B.C. He is often found writing about cars and the auto industry, amongst other things, or driving around in his work-in-progress 1990 Mazda MX-5.

Twitter: @b_yong
Instagram: @popuplights

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