Honda and Toyota left Detroit's Big Three in the dust in the Union of Concerned Scientists' (UCS) biennial ranking of the greenest automakers... Hyundai-Kia, Nissan and Volkswagen were in the middle of the pack, coming in third, fourth and fifth, respectively. Ford and General Motors, meanwhile, were at the back, and DaimlerChrysler placed last... Each automaker was rated on how its vehicles compared to the industry average on global warming and smog-forming pollution.