What Makes it a "Hybrid"?
Any vehicle is a hybrid when it combines two or more sources of power. In fact, many people have probably owned a hybrid vehicle at some point. For example, a mo-ped (a motorized pedal bike) is a type of hybrid because it combines the power of a gasoline engine with the pedal power of its rider.

Hybrid vehicles are all around us. Most of the locomotives we see pulling trains are diesel-electric hybrids. Cities like Seattle have diesel-electric buses -- these can draw electric power from overhead wires or run on diesel when they are away from the wires. Giant mining trucks are often diesel-electric hybrids. Submarines are also hybrid vehicles -- some are nuclear-electric and some are diesel-electric. Any vehicle that combines two or more sources of power that can directly or indirectly provide propulsion power is a hybrid.

The gasoline-electric hybrid car is just that -- a cross between a gasoline-powered car and an electric car. Let's start with a few diagrams to explain the differences.

Figure 1 shows a gas-powered car. It has a fuel tank, which supplies gasoline to the engine. The engine then turns a transmission, which turns the wheels.

Figure 1. Gasoline-powered car
Move your mouse over the parts for a 3-D view.

Figure 2 below shows an electric car, which has a set of batteries that provides electricity to an electric motor. The motor turns a transmission, and the transmission turns the wheels.

Figure 2. Electric car
Move your mouse over the parts for a 3-D view.

To learn about the structure of a parallel hybrid car and a series hybrid car, go on to the next page!