Hybrids also use a much smaller gasoline engine than conventional cars use for better economy. Early hybrids worked like electric cars, using an electric motor to power the wheels. The gas engine served only as a generator to keep the batteries charged. But most modern hybrids, including the Toyota Prius, use a parallel configuration that alternately uses an electric motor and batteries, a gasoline engine, or both to drive the wheels. This allows both the electric motor and the gasoline engine to do what they do best.
Gasoline engines excel at traveling long distances at highway speeds.
But they're dirtiest and get the worst fuel mileage accelerating from a stop. Electric motors, by contrast, generate full torque from a stop and never waste energy or pollute while idling. But their batteries run down quickly during long drives. So parallel hybrids start rolling silently under electric power. At about 10 miles per hour, the gasoline engine starts and drives the car.