The 15^th annual ratings, which can be found at greenercars.org, see the Toyota Prius C secure the top spot, with the Honda Fit being placed second, while Toyota’s original Prius comes in joint third with the new plug-in Prius hybrid followed by the Honda Civic Hybrid and Honda Insight.

In addition, three Ford vehicles made the list: the Focus EV and the Fusion and C-Max hybrids, which were rated in ninth and tenth places respectively.

European vehicles also placed, with VW’s new Jetta hybrid and the Smart ForTwo coming in seventh and eighth places.

Conventional vehicles were notable  by their absence, with the Scion IQ and Smart ForTwo being 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 ACEEE lead vehicle analyst Shruti Vaidyanathan.

Vehicles are analysed 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 cars.

The greenercars.org website also identifies widely-available, top models in each vehicle class.