More American drivers are starting to drift toward fuel efficient and environmentally-friendly vehicles, and automakers are improving their lineups so fast it can be hard to keep track of which cars are the greenest. This is why the American Council for an Energy-Efficient Economy (ACEEE) releases an annual compilation of the "Greenest" vehicles on the market.

This year marks the first time since the list was first published 14 years ago that an electric vehicle, the Mitsubishi i-Miev, came out on top. AutoBlog reports this is also the first time any car has beat out the Honda Civic Natural Gas in eight years. The Nissan Leaf tied the Civic for first place last year, but the i-Miev beat them both out this time.

"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," said ACEEE's lead vehicle analyst Shruti Vaidyanathan. "Just using the latest technology does not guarantee a top spot."

Drivers who aren't ready to trade in their current vehicles for more fuel-efficient models can take steps to improve the fuel economy of their rides. Keeping an eye on tire pressure and getting regular maintenance can go a long way, and an extended warranty covers the cost of any necessary repairs to keep your car on the road and running well.