How green is it:
Toyota developed an innovative power train that combines an electric motor and a gasoline-fueled internal combustion engine. This enables the Prius to provide lower emissions and higher fuel economy than regular cars. When accelerating, the electric motor and the internal-combustion engine work together, with the engine recharging the batteries. In bumper-to-bumper city traffic, the Prius alternates between the two power sources and sometimes runs on battery power alone.
A regenerative braking system converts energy usually lost as heat into electricity and uses that to further recharge the car's battery pack.
Another reason to buy a Prius is if you buy a Prius, it shows you are the best liberal on the block, it improves your environmental image instantly.(This is not an advertisement)