Automakers are providing American consumers with a huge array of gas-saving vehicles and technologies to choose from in 2012. The American Council for an Energy-Efficient Economy (ACEEE) comprehensive environmental rankings show how the different models stack up.

The Greenest list saw the Mitsubishi i-MIEV battery electric vehicle claiming the top spot from the Honda Civic Natural Gas, which has held on to first place for eight years in a row. Making its 2012 debut on the American market, the i-MIEV earns a score of 58, the highest Green Score awarded since the rankings began in 1998. With a combined city and highway fuel economy of 112 miles per gallon equivalent, the i-MIEV outpaces all other vehicles currently sold in United States. “Even taking into account the emissions generated from the electricity used to power the i-MIEV, it still handily outscores other vehicles on the market today,” says ACEEE lead vehicle analyst Shruti Vaidyanathan.

The Honda Civic Natural Gas, despite its improved fuel economy this year, appears in second place, tied with the Nissan Leaf. Rounding out the top six are the Toyota Prius, the Honda Insight and the Smart ForTwo. This year, hybrids dominate the Greenest list, occupying half of all spots.

“It’s increasingly obvious that automakers are fully invested in providing consumers with the widest possible array of vehicle choices. 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,” says Vaidyanathan.

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 contribute to climate change. This year, a number of updates were made to the Green Book methodology to more accurately estimate vehicles’ environmental impacts. These include improved emissions estimates for the vehicle manufacturing process, changes reflecting current natural gas extraction practices and consideration of upcoming shifts in the generation mix for the electricity used to power electric cars.

Source: GreenerCars.org.