With aggressive national fuel economy standards kicking in for model-years 2012 to 2025, automakers have provided an impressive array of efficient vehicle options for 2013, according to new environmental automotive ratings released by the American Council for an Energy-Efficient Economy (ACEEE).

The "Greenest" list is dominated by new models this year, with the Toyota Prius C securing the top spot with a Green Score of 58. Having made its debut on the American vehicle market in 2012, the Prius C is Toyota's compact addition to the Prius family. The original Prius (#3), the new plug-in Prius hybrid (#4), and the larger Prius V (#11) all made the "Greenest" list this year as well. Other top scorers are the Honda Fit electric vehicle (#2) and the Honda Civic Hybrid (#5). Three Ford vehicles made the list: the Focus EV and the Fusion and C-Max hybrids. European vehicles also placed, with VW's new Jetta hybrid and the Smart ForTwo placing #7 and #8.

This year, conventional vehicles were largely driven off the "Greenest" list by hybrid-electric, plug-in hybrid-electric, and all-electric vehicles. The Scion IQ and Smart ForTwo are the only non-hybrid, non-plug-in vehicles to remain on the list. Even the 8-time first-place Honda Civic Natural Gas vehicle was pushed out of the top twelve in 2013.

"The vehicles at the top of this year's rankings are proof that automakers are really ramping up their offerings. There are more hybrid and electric options on the market this year than ever before and the race for a spot on the Greenest list is increasingly competitive. Automakers have revamped their offerings to meet the growing demand for efficient vehicles and new fuel economy standards," said Shruti Vaidyanathan, ACEEE lead vehicle analyst.

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 methodology to more accurately estimate vehicles' environmental impacts. These include updates to emissions from the vehicle manufacturing process; changes to gasoline, diesel, and natural gas upstream emissions; and updates to the forecasted mix of fuels used to generate the electricity used to power electric vehicles.  

Domestic manufacturers claimed six of the 12 "Greener Choices" spots.