No longer is Honda the "greenest" automaker on the planet, a new report suggests, with Hyundai taking over the mantle as the environmentally friendliest manufacturer on the planet. The findings were published by the Union of Concerned Scientists and details how Hyundai through its smaller engines and fuel economy, have become the leader in the green auto sector.

Honda fell to second for the first time in the report, which has been issued eight times since 2000. The study looks at the eight leading car companies in the United States and ranks them according to their green standards.

Coming in third was Toyota, followed by Nissan and Volkswagen. The three top American automakers, Ford, GM and Chrysler fell to the bottom of the list, with them even scoring below the industry average.

The report did have positive news, even for the Detroit big three, which said that all companies across the board had made efforts and succeeded in reducing their carbon footprint and making cars that are better suited for the environment and challenges faced with climate change.

Even the report authors were pleased with the findings.

"For too many years, clean car standards were stagnant and automakers were more likely to promote extra cup holders instead of fuel economy," said Dave Cooke, a vehicles analyst in the Clean Vehicles Program and the author of the report.

"Now, consumers are demanding cars that go further on a gallon of gas and new standards are pushing the automakers to deliver. The big lesson here is that the smog and global warming standards are working and there is much more to be gained as these standards progress."

One of the major reasons that Hyundai was able to overcome Honda was largely due to how the automaker revised performance with the United States Environmental Protection Agency (EPA), which showed that the automaker was making massive strides on all green technology fronts.

It also introduced two hybrid-electric versions of its highest selling models, the Sonata and the Kia Optima. That went a long way in showing that car makers can downsize their engines while maintaining performance.

Cooke did say that Honda is maintaining its edge in a number of sectors.

"Honda continues to lead the way in many vehicle classes, but it's started to lag the industry average in its midsize fleet-which includes its best-selling Accord, and accounts for a quarter of the company's sales," said Cooke.