Although for the better part of a decade the Honda Civic Natural Gas was ranked the greenest car on the road by the American Council for an Energy Efficient Economy (ACEEE), this year it was upstaged by a new contender, Mitsubishi’s all-electric i.

On ACEEE’s 2012 Greenest Vehicle List, the Mitsubishi – still known in other markets as the i-MiEV – scored a total of 58 points, placing it ahead of the Civic Natural Gas, which had won the category the previous eight years in a row. The Civic tied for second place with Nissan’s all-electric Leaf, followed by the Toyota Prius Liftback and Smart ForTwo.

Out of the top 12 vehicles listed, half were hybrids. Besides the Prius and Insight, the others were the Honda Civic Hybrid (ranked 8th), Lexus CT 200h (ranked 9th), Toyota Camry Hybrid (ranked 10th), and Honda CR-Z (ranked 11th).

According to ACEEE lead analyst Shruti Vaidyanathan, “It’s increasingly obvious that automakers are fully invested in providing consumers with the widest possible array of vehicle choices.” Yet Vaidyanathan also said that “earning a spot on the ‘Greenest’ list is proving to be a real challenge for automakers, given the variety of vehicle technologies on the market and the proliferation of highly efficient conventional vehicles. Just using the latest technology does not guarantee a top spot.”

Nonetheless, as far as the mid-engine, rear-wheel-drive Mitsu i is concerned, its maker has every reason to be proud – the car scored the highest number of points since the Greenest Vehicle Awards began in 1998 with a combined city/highway fuel economy equivalent rating of 112 miles per gallon. This ranks it higher than any other vehicle currently on sale in the U.S.

“Even taking into account the emissions generated from the electricity used to power [the i],” said Vaidyanathan. “it still handily outscores other vehicles on the market today.”

ACEEE