The major advantages of hybrid cars are that they have lower fuel consumption than standard automobiles, but this is offset by the higher cost of most hybrid models. In addition, a hybrid car's advantages in fuel efficiency are largest in city driving, making them less beneficial for frequent highway travelers.
Hybrid cars combine a conventional combustion engine with electric motors and batteries, allowing them to achieve higher fuel efficiency by using both power systems in tandem. Some hybrid cars drive their wheels with both the electric motor and the combustion engine, while others use the electric engine exclusively for powering the wheels and only provide charging with the combustion engine. Using electric engines for some portion of a car's driving force has many advantages, including the ability to run the car on electric power alone for short distances. Hybrid cars can also benefit from technologies, such as regenerative braking, where energy that would be lost during braking is transferred back through the hybrid system to recharge the battery.
Because the electric engines in most hybrid cars are only suitable for short distances and relatively low speeds, they are most advantageous in city driving. The frequent braking required in heavy traffic also allows for hybrids with regenerative braking to take full advantage of this feature. At sustained highway speeds, the electric motors contribute relatively little driving force in many hybrid designs as compared to the combustion engine, and the battery cannot be recharged through regenerative braking. Hence, the gas mileage of a hybrid on a clear highway is not usually much better than that of a conventional car.