A hybrid car is an automobile that has two or more major sources of propulsion power. Most hybrid cars currently marketed to consumers have both conventional gasoline and electric motors, with the ability to power the vehicle by either one independently or in tandem. These vehicles are appropriately termed gas-electric hybrids. Other power sources may include hydrogen, propane, CNG, and solar energy. The technology used depends on the goals set for the vehicle, whether they be fuel efficiency, power, driving range, or reduced greenhouse gas emissions. Consumer oriented hybrid cars, which have been on the market for about ten years, are usually tuned for reduced emissions and driving range. Additionally, owners of hybird vehicles often enjoy social benefits such as prestige and discounted secondary services. Some Chicago hotels as well as hotels in other cities give parking discounts to people driving hybrid cars. Corporate and government fleets that have been in service for twenty years or more are usually tuned for fuel efficiency, often at the cost of driving range, power, and hydrocarbon emissions.
A gasoline-electric hybrid car has one or two auxiliary electric motors that supplement the main gasoline engine. Compared to conventional automobiles, the gasoline engine in a gas-electric hybrid is smaller, less powerful, and more efficient. Although the gasoline engine alone would be sufficient to power the vehicle under most circumstances, during maneuvers requiring unusually high power the electric motor is used as well. These conditions include passing, hill climbing, and acceleration from a standstill. Some hybrid cars, such as the Toyota Prius, shut down the gasoline engine under conditions in which the electric motor alone would suffice, such as coasting and breaking. In fact, the Toyota Prius has a special electric-only mode designed for stop-and-go traffic. This is made possible by the super heavy duty electric motor used in the Prius, which is capable of propelling the vehicle from a standstill without the gasoline assist. Thus, in contrast to most other hybrid vehicles, the Prius actually uses the electric motor more than the gasoline engine.
Many of the technologies found in hybrid vehicles would benefit vehicles of any type, including conventional gasoline automobiles. However, the engineering and manufacturing costs associated with these technologies often would increase the price of the vehicle to the point where the fuel savings are negligible in comparison. Only in tax-subsidized electric and hybrid vehicles are these technologies practical, in which associated cost increases are absorbed by the government instead of the manufacturer or consumer. These technologies include regenerative braking, aerodynamic refinements, and lightweight building materials.
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