a hybrid car uses a combination of fuel sources to power the engine. typically, this involves a regular combustion gasoline engine and a small battery connected to an electric motor. when a driver is idling at a stop light waiting for the light to turn green, a hybrid car uses only battery power. this means pollution levels will be reduced. when the engine is producing a lot of power, excess energy from the brakes are used, excess power is stored in the battery. hence, hybrid cars are very efficient for city driving due to all the stopping and starting. but for a hybrid cars might only be popular for small cars, not all for makes and models.