Toyota studied the car's total environmental impact from factory to junkyard.
Not surprisingly, the fuel-efficient Prius was better than average in its class of vehicles in lifetime emissions of carbon dioxide, nitrogen oxide and sulfur oxide, according to Toyota.
But it was slightly worse than average in emissions of nonmethane hydrocarbons and particulate matter. Toyota says this is because producing hybrid-only parts such as motors, inverters and nickel-metal hydride batteries consumes more energy and creates more emissions.