Well, now it's official. The 2010 Toyota Prius offers the best gas mileage of any new car sold in the U.S. for the upcoming 2010 model year, with a blended EPA rating of 50 miles per gallon.

The 2010 Prius had actually been rated at 50 mpg back in March, but the U.S. Environmental Protection Agency had to finish rating all 2010 models before it could issue a definitive list.

Its formal ratings are 51 mpg city / 48 mpg highway on the EPA's two cycles.

The 2010 Prius returns better overall gas mileage than the 2009 Prius it replaced, which was rated at 48 city / 45 highway. The new car is both more powerful and offers more luxury features.

Dealer stocks of 2010 Prius models remain low, due to strong global demand  for the world's most popular hybrid car. Nine of the 10 highest-mileage cars on the EPA list, in fact, were hybrids from Ford, Honda, Lexus, Mazda, Mercury, Nissan, and Toyota.

[2010 Fuel Economy Guide]