A hybrid car has two or more on-board energy sources and most often features electric power combined with at least one other energy source. Electronically Controlled Continuously Variable Transmission technology allows management of transitioning back and forth to each energy source, and a regenerative braking system recharges the battery when the car slows. Mild hybrid cars are defined by a primary reliance on gas engine power for propulsion, with electric power secondary. Full hybrid cars rely on electric power for propulsion and the secondary gas engine for power and acceleration.

The typical hybrid utilizes a gasoline engine and an electric motor, and rechargeable batteries store the energy used by the electric motor. For a lot of vehicles these rechargeable batteries are also replaceable. The driver doesn’t have to worry about which energy source to use to maximize efficiency, since a computer system determines when to switch systems. These hybrids use less gasoline since they also use electricity as a fuel. Some future hybrids may be plug-ins, with the ability to be recharged at home. As hybrids become more common it is clear the plug-in kind we’ll be the most attractive. Despite the possibility of developing plug-ins in a wider range, most consumers are buying battery powered hybrids.

Other hybrids have alternative fuel tanks that use traditional gasoline and another fuel, like compressed natural gas (CNG). Although not renewable, CNG is cheaper and is readily available. More similar to conventional gas engine cars, flexible fuel vehicles have a single fuel system which can run on two separate fuels like gasoline and E85, or a blended fuel. A more environmentally friendly option is removing gas engine power altogether. French manufacturer Venturi is in the process of developing a car that features two alternative fuel sources, solar photovoltaic cells and electric power.