According to the Environmental Protection Agency, Americans are slowly switching over to fuel-efficient vehicles, buying slightly more of the efficient vehicles in 2008 than in 2007 -- a trend that's expected to continue this year.

Not only are purchases up, but new cars are themselves more efficient. Overall, new U.S. vehicles in 2008 were 2 percent more efficient than the previous model year, achieving 21 mpg versus 20.6 (the EPA uses real-world efficiency estimates rather than automakers' claims). However, 21 mpg is a far cry from the 35.5 mpg the Obama administration has called for by 2016 -- a goal that automakers have pledged to meet. That's a massive increase in fuel efficiency in only six or so years. The EPA estimates 2009 models will have an ever-so-slightly-better efficiency of 21.1 mpg.

Among automakers, Honda leads the way with an average fleet ranking of 23.9 mpg; running close behind are three more Asian automakers -- Hyundai, Kia and Toyota. Chrysler, at only 19.3 mpg, comes in dead last. Ford, though not ranked in the top slate for efficiency, did make the biggest year-over-year efficiency gain, from 19.4 mpg in 2008 to 20.5 in 2009.

(Pictured: A 2010 Honda Civic Hybrid)

(Sources: The Detroit Free Press, USA Today)