The Union of Concerned Scientists has named Hyundai-Kia as the greenest automaker, which has beat Honda.
The scientists' group has ranked the eight top-selling automakers based on carbon and smog-forming emissions of their fleets, who they say have reduced pollution for the first time, Fox News reported.
Hyundai-Kia beat Honda by equipping many models with smaller turbocharged engines and the researchers said that the automaker introduced gas-electric hybrid versions of its two top-selling models, the Hyundai Sonata and Kia Optima.
Toyota, Nissan and Volkswagen tied for third place, while Detroit automakers, finished at the bottom and Ford was the highest-ranked Detroit company.
