James R. Healey

USATODAY

Combined car company Hyundai-Kia, both owned by South Korea's Hyundai Motor Group, overtook Honda Motor as the "greenest" automaker in the U.S., according to a report today by the Union of Concerned Scientists.

For the first time since UCS began tracking the environmental friendliness of automakers in 1998, all eight major companies it rates improved their scores in the past year.

Hyundai and Kia are marketed as two separate brands in the U.S. and are operated separately. Elsewhere, they are considered two brands sold by a single, combined automaker.

The rankings lean heavily on vehicles' tailpipe emissions.

Key to the Hyundai-Kia championship: "Turbocharging and downsizing engines in a number of its models while also introducing hybrid-electric versions of two of its top-selling vehicles, the Hyundai Sonata and Kia Optima," UCS said.

Honda leads in a number of categories, but hasn't kept up with fast-moving "green" targets with its Accord in the mid-size category, UCS said, even though Accord is available as a gas-electric hybrid.

Honda finished second in the report card.

Third was a three-way tie: Toyota, Nissan, Volkswagen.

UCS said, "The Detroit Three – Ford, General Motors, and Chrysler – continue to bring up the rear, as they have in every automaker ranking.

"However, some domestic automakers are making greater strides than others. Ford led the Detroit automakers while achieving the greatest percent reduction in smog-forming emissions of any manufacturer evaluated.

"The company also enjoyed strong improvements in global warming emissions due to its increased use of hybrids and its focus on smaller, turbocharged engines in vehicles ranging from the Ford Focus sedan to its iconic, best-selling large pick-up, the F-150, demonstrating that fuel-economy gains are possible across an automaker's entire fleet".