What’s the difference between an electric car and a hybrid?

The first generation of hybrids, such as the Toyota Prius, are powered by a battery as well as an internal combustion engine. The battery, which is recharged by the vehicle itself, is the sole source of power only at low speeds. Models now in the pipeline will scale back the role of the petrol engine. General Motors’ Chevy Volt, to go into production late next year, is a plug-in hybrid. It will run, even at high speeds, for up to 40 miles on battery power. When the battery is depleted, a small petrol engine will generate electricity without driving the wheels of the car. But the holy grail is a vehicle powered entirely by batteries.