Fifteen out of 37 automotive brands are represented in the top 30 list of environmentally friendly vehicles, according to the inaugural J.D. Power and Associates Alternative Powertrain Study. The Alternative Powertrain Study (APS) includes the Automotive Environmental Index (AEI), which combines U.S. Environmental Protection Agency publicly available information with voice-of-the-customer data related to fuel economy, air pollution and greenhouse gases for 2006 model-year vehicles...Volkswagen ranks highest among nameplates in the Automotive Environmental Index, with three models in the top 30. [also refers to Toyota, Honda, Mazda, Lexus (part of Toyota), Acura (part of Honda)]