Hybrid cars are vehicles that include a motor/generator to assist both the engine and the brake. The motor/generator is attached to a relatively large rechargeable battery and the interactions between the engine and the other equipment are computer controlled. The motor/ generator assists the engine during acceleration by allowing the battery to power the motor/generator as a motor. When decelerating, the motor/generator acts as a generator and uses the car?s motion as energy to recharge the battery. This slows the car while assisting the brakes. Thus, part of the car?s motion is turned into electricity that is stored for reuse later when additional pickup is needed. No other gasoline car has this feature called ?regenerative braking.? Conventional braking involves friction which literally ?grinds to a halt,? wasting all the mechanical energy as heat. So you can slow your car down by storing some of the energy and using it later. Hybrid cars can therefore get better mileage especially in ?stop and go? city driving. Engines and brakes can be made smaller and the engines can be redesigned to operate under a less variable range more efficiently. The engine is turned off when stopped, or even at low speeds. The motor is more efficient then and the engine can come on for recharging purposes. So is it worth it? Of course it costs more money for the additional equipment and design, but you may get much better mileage. If not worthwhile now, it will be in the future as the batteries get smaller and cheaper while fuel costs keep rising.