The Toyota Prius is among the greenest cars to operate. But manufacturing the famous gasoline-electric hybrid can be a dirty business.
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.
In fact, when looking at the "materials manufacturing" phase of the car's life cycle, the Prius was worse than the class average across all five emissions categories.
Toyota said it conducted life cycle emissions assessments on eight vehicle series last year and used the results to help redesign such models as the Prius, Lexus RX 450h and HS 250h and such Japan-market vehicles as the Wish minivan and Mark X sedan.