A hybrid vehicle is one that has more than one fuel or power source. Hybrids work on the concept that a vehicle doesn't require its maximum possible power output 100 percent of the time. The advantage of this kind of setup is that the fueled engine can be smaller and more efficient. When the vehicle is idling or coasting, the engine makes up enough power to carry it through the next hill or acceleration.

The most common hybrid is a gas or diesel generator, working in conjunction with an electric motor. The power made by the generator is stored, or "buffered" in a battery pack, much in the same way as a purely electric vehicle. In a hybrid vehicle, the battery pack is typically smaller, since it is constantly being charged- even during use. The electric motor then uses this to power the vehicle. In some implementations, this is the exclusive provider of motion. In others, the engine and motor are actually coupled together, such that either or both may power the vehicle. This allows the vehicle to operate very efficiently, yet work together to provide more adequate power when demanded.