The American Council for Energy-Efficient Economy (ACEEE) has released its environmental ratings for 2010 model year vehicles. This is the 13th year that ACEEE has published its rankings as part of the organization's environmental guide to cars and trucks, Green Book Online.

Scrambling to recover from last year's sales slump and bankruptcies, manufacturers are introducing an array of new vehicles designed to meet the demands of fuel-conscious buyers and increasingly stringent fuel economy standards. "With the Chevrolet Volt and Nissan Leaf both scheduled to make appearances in the latter half of 2010, manufacturer interest in advanced technologies is even more intense, with a particular emphasis on electric vehicles," said ACEEE Vehicle Analyst Shruti Vaidyanathan. "But the eco-stars this year are once again hybrids and smaller, conventional vehicles. Gasoline vehicles are evolving fast, but manufacturers continue to devote much new efficiency technology to boosting power."

The "greenest vehicle" title goes once again to Honda's natural gas-powered Civic GX, while the Toyota Prius and the Honda Civic Hybrid claim spots two and three. New arrivals to the "Greenest" list this year are the Honda Insight, the Ford Fusion/Mercury Milan Hybrid (named the 2010 North American Car of the Year), and the Hyundai Accent Blue. The remainder of the "Greenest" list is comprised largely of highly fuel-efficient conventional vehicles such as Smart Fortwo Convertible at number four and the Chevrolet Cobalt XFE and its Pontiac G5 XFE twin at number 10.

Just missing out on inclusion in the top-12 "Greenest" again this year are the diesel-powered Volkswagen Jetta and Jetta Sportwagen, part of a crop of "clean diesels" introduced in the United States last year. "While clean diesels once again perform well on our annual ranking, high prices both for the vehicles and for diesel fuel have kept them from really catching on thus far. They're not having the impact in the U.S. that they have had in Europe, and as a result, manufacturers are scaling back production and promotion of diesels," said Vaidyanathan.

Widely regarded as the pre-eminent buyer's guide to environment-friendly passenger cars, trucks, and SUVs, provides the facts necessary to examine the eco-performance of any 2010 model. Vehicles are analyzed on the basis of a "Green Score," a singular measure that incorporates unhealthy tailpipe emissions, fuel consumption, and emissions of gases that cause global warming.

The "Meanest" list this year remains largely unchanged from 2009. It is comprised once again of a variety of heavy-duty trucks and SUVs and luxury European vehicles. The Lamborghini Murcielago tops the list this year with a Green Score of 18.

Top 12 Greenest Vehicles

  • Honda Civic GX
  • Toyota Prius
  • Honda Civic Hybrid
  • Smart Fortwo Convertible/Coupe
  • Honda Insight
  • Ford Fusion Hybrid/Mercury Milan Hybrid
  • Toyota Yaris
  • Nissan Altima Hybrid
  • Mini Cooper
  • Chevrolet Cobalt XFE/Pontiac G5 XFE
  • Hyundai Accent Blue
  • Honda Fit

Top 12 Meanest Vehicles

  • Lamborghini Murcielago/Murcielago Roadster
  • Bugatti Veyron
  • Bentley Azure/Brooklands
  • Mayback 57S
  • Dodge Ram 2500 Mega Cab (Class 2B)
  • Ford F-250 (Class 2B)
  • Bentley Continental GTC/Continental Flying Spur
  • Ferrari 612 Scaglietti
  • Mercedes-Benz ML
  • Chevrolet Suburban K2500
  • GMC Yukon K2500 (Class 2B)
  • Mercedes-Benz G550