Honda's Insight was the first hybrid car made commercially available in the US
Hybrid car batteries
The on-board batteries in hybrid cars are recharged by capturing the kinetic energy created when using the brakes (commonly referred to as "regenerative braking"), and some hybrids use the combustion engine to generate electricity by spinning an electrical generator to either recharge the battery or directly feed power to an electric motor that drives the vehicle.
Full hybrids vs. mild hybrids
Generally, there are two kind of hybrid cars: full hybrids and mild hybrids. Full hybrid systems allow both the gasoline engine and electric motor to provide power to the wheels; often, this allows the vehicle to shut down the gasoline engine when stopped at a red light, and to start driving the car on electric power only. The hybrid systems available from Toyota, Lexus and Ford employ this technology.
Mild hybrids, by contrast, use the electric motor primarily to boost the performance of the gasoline engine, when it needs extra power; this technology is seen most often in the hybrids sold by General Motors. In the mild hybrid vehicles available today, most use what's known as a Stop/Start hybrid system, which shuts the gasoline engine off at idle (like at a red light) and instantly starts it up again on demand (like when the light turns green and you hit the accelerator). For a full explanation of the differences between full and mild hybrids, see this article at HybridCars.com.
With all this technology, which hybrids are actually for sale? Read on for details on which hybrid cars you can buy along with more explanation of how they work, and what's on the horizon for hybrid cars.