Their UCS study, called Automaker Rankings 2007: The Environmental Performance of Car Companies, examined the emissions from every car made by eight car makers, representing 96% of cars and trucks sold in the US. The report lauds Honda for achieving the better-than-average smog scores in every class, while Toyota, which came in second, was praised for being the only manufacturer to improve its global warming performance every year since 2001. (Honda's environmentally-themed F1 team was left out of the study.) Of the eight automakers studied, The Big Three came in as the last three, with DaimlerChrysler earning the UCS's Rusty Tailpipe award as the dirtiest automaker.
To paraphrase Gordon Gecko, when it comes to Honda, "green is good." The Union of Concerned Scientists, a non-profit advocacy group out of Cambridge, Massachussetts, voted Honda the country's greenest automaker for the fourth time in a row.