Green cars gain momentum with American drivers

It's taken a while -- decades, actually -- but it appears American consumers have warmed a bit to the concept of green, more environmentally friendly cars.

The U.S. Energy Information Administration reports that as of 2011, over 11 million alternative fuel vehicles were on the nation's roads compared to around 250,000 in 1995.

And those figures include over 2 million hybrid gas-electric and diesel-electric vehicles, with the majority of the other alternative cars and trucks falling into the flexible fuel vehicle (FFV) category, meaning they can operate on gasoline, gasoline-ethanol blends or a mixture of the two.

To be sure, that's still just relative handful -- considering the U.S. has well over 250 million cars and trucks, with 99 percent of those vehicles operating primarily on gasoline or diesel. Still, the most recent gas and diesel-fueled vehicles are have much better mileage than earlier versions.

"Based on our monthly monitoring, the average EPA-rated fuel economy of new vehicles has improved from 20.1 mpg in October 2007 to 25.4 mpg in March 2015," Michael Sivak, director of Sustainable Worldwide Transportation at the University of Michigan's Transportation Research Institute, told CBS MoneyWatch.

This represents an improvement of about 26 percent in new-vehicle fuel economy over the past eight years, although Sivak warns those improvements have stalled recently as consumers take advantage of the historic drop in oil prices.

Nevertheless, more Americans are paying attention to their car's carbon footprint, even if it's just so they can keep their personal costs down.

"The list of 'green' vehicle standouts continues to blossom, and with strict Corporate Average Fuel Economy (CAFE) requirements coming down the pipeline, auto manufacturers are making stronger advancements each year in creating more environmentally friendly vehicles," Jack Nerad, executive editorial director and executive market analyst for Kelley Blue Book, said in a press statement.

And for the seventh straight year, Kelley Blue Book has issued its 10 Best Green Cars list just in time for Earth Day. Here's their list, in descending order:

10. Volkswagen Jetta TDI

9. Ford C-Max Hybrid

8. Toyota Camry Hybrid

7. Chevrolet Volt

6. Tesla Model S

5. Honda Accord Hybrid

4. Toyota Prius

3. Nissan Leaf

2. Volkswagen e-Golf

1. BMW i3

Matt Degen, a senior associate editor at Kelley Blue Book's KBB.com, said he sees several factors at play when it comes to the rising consumer acceptance of green cars. First is gas prices.

"While they are low now, they've been fluctuating so much over the past few years that more and more consumers are realizing that what goes down will likely go back up," Degen said. "With that in mind, savvy shoppers of fuel-efficient green cars understand there are savings to be had both now and in the years ahead, especially if we experience another spike in oil prices."

Second, carmakers are starting to cater to a wider diversity of consumers looking for green vehicles.

"Whether it's a modestly priced diesel sedan like the Jetta TDI that's capable of achieving up to 46 mpg," Degen added, "or the cutting-edge Tesla Model S all-electric luxury car, there's something for everyone at a range of price points."