GT5 Transcripts/Toyota PRIUS G (J) '02

Making its debut in December 1997, the Toyota Prius has become the first ever mass-produced hybrid vehicle in the world. A hybrid is more fuel-efficient than a conventional gasoline-powered vehicle because it uses an electric motor and a battery pack to compensate for some of the inefficiencies of the internal combustion engine.

In the case of the Prius, the 57 BHP 1.5-litre inline-4 gasoline engine; the first generation Prius, was supplemented by an electric motor that produced the equivalent of 39 BHP. In general, the motor powers the car at very low speeds, where electric motors operate best, while the engine takes over for normal driving. The motor may also kick in to assist the engine during rapid acceleration. When the car decelerates or the driver applies the brakes, the drive motor switches and becomes a generator, storing this energy in the battery pack through regenerative braking. The Prius performs these functions via an integrated control powertrain the company calls Toyota Hybrid System (THS).

The THS essentially did away with a conventional transmission, instead using epicyclical gearing that acted as a variable speed gear in distributing power from both the engine and the motor. These hybrid interactions created a somewhat odd driving experience compared to a conventional car, but the latest Prius has ironed some of this out.