A hybrid car works by combining two smaller engines to produce the power of a larger engine. Usually, it's a gas engine and an electric engine. For instance, in the Toyota Prius it's currently a 106 horsepower I-4 engine combined with a 67 horsepower electric engine to produce a 173 horsepower car, about the same as any other I-4 engine or a small 6-Cylinder engine. In the near future, Volkswagen is said to be introducing a new diesel/electric hybrid which will acheive close to 80 miles per gallon and can be used in a standard small car, including the Beetle, Golf, and Jetta.

To improve fuel mileage and exhaust emissions, the electric engine does the work of starting the car and getting it going from a complete stop. In some hybrids, the electric engine is active all the way up to 35 miles per hour. One the vehicle is moving, the gas engine starts up and gives the car more power in addition to recharging the electric motor's batteries. The gas mileage operates at higher speeds because gas mileage improves with speed up to 65 miles per hour, after which it begins to drop again.

Another way the hybrids are used is as a sort of electric supercharger (mainly Honda and Lexus use them for this) to give the engine added power at lower speeds before letting the gas engine take over after a preset speed.

One thing I will say about your purchasing a hybrid vehicle is to be careful which ones you go for. Toyota's Prius, because of the heavy weight of the batteries and the added electric motor, doesn't get all that much better mileage than the Toyota Corolla. The Prius, which is rated at 60 miles per gallon in city driving and 51 on the highway, has been found to get closer to 51 city and 40 on the highway (Consumer Reports, Motor Trend, Car and Driver, etc. have all found this to be the case). The Toyota Corolla has been found to get 32 miles per gallon in the city and 41 on the highway, with some people reporting even higher mileage. Plus, the Prius costs a lot more than the Corolla, and, in my opinion, the Corolla looks a lot better. To reimburse your loss in cash over buying the Prius, you'd have to drive it for over 90,000, and that's assuming the gas mileage doesn't drop with age. An even worse case would be Chevrolet's Silverado Hybrid, which gained just 1 mile per gallon at the expense of over $5,000.

The only hybrids which have gotten similar numbers to what's been promised have been the Ford Escape Hybrid, Honda Civic Hybrid, Mercury Mariner Hybrid, and Toyota Camry Hybrid. All of these vehicles have been reliable and are selling well. If you want to save even more money, consider a diesel-powered Volkswagen, like the aforementioned Beetle, Golf, and Jetta diesels, which have been acheiving 41-46 miles per gallon and higher. Plus, the diesel engines are more efficient than the gas engines and far more reliable.

If you have any more questions, please feel free to ask.