Hybrid Synergy Drive is defined as a "full hybrid system," which means it is capable of operating in gas or electric modes, as well as a mode that combines the power of the gas engine and electric motor.

In Toyota Prius, Hybrid Synergy Drive combines a 1.5-liter four-cylinder Atkinson Cycle gasoline engine and an electric drive motor. The gasoline engine produces 76 horsepower and 82 lb.-ft. of torque. As on all other Toyota passenger car engines, Variable Valve Timing with intelligence (VVT-i) helps to optimize power delivery across the engine speed range.

The permanent-magnet electric drive motor produces its maximum power of 50 kW (67 horsepower) from 1,200-1,540 RPM, and peak torque of 295 lb.-ft. from 0-1,200 RPM. The Prius produces 110 combined horsepower with its gas engine and electric motor.

The electronically controlled planetary gear-type continuously variable transmission does not have fixed gear ratios, but rather provides infinitely variable ratios in response to driving conditions.

A regenerative braking system further boosts system efficiency: when the Prius is coasting or the brakes are applied, the electric motor functions as a generator, capturing kinetic energy that would normally be lost as heat through the brakes and transforming it into useable electricity to recharge the batteries.


Driving Toyota Prius

One of the most remarkable features of the Toyota Prius is what the driver does not feel. The computer-controlled powertrain seamlessly blends power from the gasoline engine, the electric drive motor and the generator. The driver typically does not feel the vehicle changing operational modes.

The Prius uses an electronically controlled "by-wire" throttle. A by-wire shift control replaces the traditional gearshift lever and allows tap-of-the-finger shifting using a small joystick mounted on the dash.

The Prius driver can monitor electric-gas power distribution through the Hybrid Synergy Drive system on the standard seven-inch touch-panel display monitor. This screen also displays navigation information on vehicles equipped with the optional navigation system.


The Most Stringent Emissions Certification

Toyota Prius produces over 70 percent fewer smog-forming emissions than the average new vehicle. The Prius has been certified as a Super Ultra Low Emission Vehicle (SULEV) in California and those states adopting California standards. In the rest of the country, Toyota Prius is certified as Tier 2, Bin 3. In addition, In California and states adopting the California rules, Prius is certified as an Advanced Technology Partial Zero Emissions Vehicle (AT-PZEV). The AT-PZEV certification requires the SULEV exhaust standard linked with the ability to meet a zero-fuel-evaporative standard, a 150,000-mile durability demonstration, extended emissions system warranty, and technology deemed by the California Air Resources Board (CARB) to advance future fuel cell vehicles.

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