The American Counsel for Energy Efficient Economy (ACEEE) released it’s result of green cars for 2011. At the top of the list is the Honda Civic GX. It’s the second year in a row that Honda’s popular Civic has topped the chart. The Civic GX runs on compressed natural gas rather than regular gasoline or diesel fuel, so it puts off less harmful emissions, according to the ACEEE.

Hybrid cars continue to rank well on the ACEEE’s list of fuel efficient vehicles, with the Nissan Leaf ranking second behind the Civic GX. The use of electricity and other alternative fuels cause lower emissions than standard gasoline vehicles.

However, availability played a large role in the ACEEE’s ranking of green cars. The Smart forTwo EV actually received a score of 60 overall, compared to the Civic’s score of 54, but the company is releasing a very limited number into the United States to test the market.

The Chevy Volt actually ranked 13th, according to ACEEE’s corrected release on February 16th, behind the Mazda 2 because of its weight. Although hybrid cars don’t release as much harmful emission, the ACEEE determined that heavier vehicles are more likely to release more pollution that lighter ones, and the Volt ranks among the heavier hybrids for 2011.

The lowest ranking vehicles on the green list of fuel efficient vehicles include the Bugatti Veyron, the Chevrolet Suburban K2500, and the GMC Yukon XL K2500. They are considered the least environmentally friendly by the ACEEE, according to their latest reports.