On last year's list of Top 10 Green Cars, Kelley Blue Book cited skyrocketing gas prices, a weak economy and growing environmental consciousness as the major reasons more car buyers were focusing on fuel economy. As we approach Earth Day 2009, gas prices have come back to Earth but the shaky economy is trumping most other concerns and causes. Result: far fewer car buyers.

The current sales slump is unfortunate for many reasons, one of which is that 2009 is shaping up to be a banner year for fuel efficiency. The year's arrivals include an all-new Toyota Prius that's even more fuel-efficient than its world-beating predecessor, a new Prius alternative in the Honda Insight and a range of new 50-state clean-diesel cars, among others.

In addition to these newcomers, this year's list highlights some familiar faces, and it was again compiled to include a variety of vehicle shapes and sizes because not everyone who wants to get greener can go smaller.

Here, presented in order of combined EPA-estimated fuel economy, are Kelley Blue Book's Top 10 Green Cars for 2009: 

2010 Toyota Prius | 50 mpg (51 city, 48 highway)
The third-generation Prius has arrived with sleeker looks, added creature comforts, upgraded performance and even-better fuel economy. Despite a larger engine, 24 additional horsepower and quicker acceleration, the new Prius manages to deliver four more miles per gallon than its predecessor. The coolest new option is a glass moonroof with a solar-powered ventilation system, but the list also includes voice-activated navigation and Dynamic Radar Cruise Control with Lane Keep Assist. 

2010 Honda Insight | 41 mpg (40 city, 43 highway)
With a starting sticker price of $20,470, the all-new Honda Insight is the least expensive full-production hybrid available in the U.S. Even the top-level Insight EX with Navigation that includes features like a voice-activated navigation system, Bluetooth phone connectivity, upgraded audio system and electronic stability control is just $23,770. These figures should give the Insight a clear price advantage compared to the newest Prius, for which pricing has yet to be announced. 

2010 Ford Fusion Hybrid | 39 mpg (41 city, 36 highway)
The Ford Fusion is getting better with age, and perhaps the best addition is the hybrid version. For the 2010 model year, the lineup benefits from new exterior styling and an interior redesign, which grace the new hybrid version that handily out-economizes both the Toyota Camry (33 city/34 hwy mpg) and the Chevy Malibu (26 city/34 hwy mpg) hybrids. We were fans of the Fusion before, but even bigger believers after seeing and driving the latest iterations. 

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2009 VW Jetta SportWagen TDI | 34 mpg (30 city, 41 hwy)
Not long ago, VW's familiar diesel moniker vanished from the automaker's top-selling Jetta, but it has made a proud return for 2009. This time, the Jetta TDI and Jetta SportWagen TDI will be available in every state, a point that surely helped the Jetta TDI take home the 2009 Green Car of the Year award. Returning mpg that's roughly 40% better than its gas-powered equal, the Jetta SportWagen TDI combines utility, world-class efficiency and Euro driving dynamics in one well-rounded green machine. 

2009 MINI Cooper | 32 mpg (28 city, 37 highway)
The MINI Cooper balances fun and efficiency like nothing else on the road. Responsive steering, a sport-tuned suspension and diminutive dimensions combine to deliver a driving experience that instantly evokes allusions to the proverbial go kart. Combine that kind of athleticism with highway fuel economy up to 37 miles per gallon - and a personality bigger than the car itself - and you've got a unique brand of feel-good fun. 

2009 Ford Escape Hybrid | 32 mpg (34 city, 31 highway)
We like compact crossovers for their smart mix of utility and efficiency, and the 2009 Ford Escape Hybrid is the most fuel-efficient SUV in the country. After undergoing a major overhaul for the 2008 model year, the Ford Escape Hybrid is improved again for 2009 with smoother braking and electric-to-gas transitions, plus a one-mile-per-gallon improvement in highway fuel economy. 

2009 Honda Fit | 31 mpg (28 city, 34 highway)
The Toyota Yaris remains the category's mileage champ, but the Honda Fit so handily outshines its competitors in our eyes that it's making the list again this year. We're especially fond of the Sport model and its performance-tuned suspension and paddle shifters, but even base models are fun. If you're more interested in pure practicality than driving pleasure, be sure to check out the Fit's flexible back seat and impressive cargo-carrying abilities. The Honda Fit may be a little car, but it's a lot of car. 

2009 BMW 335d | 27 mpg (23 city/36 highway)
BMW's new diesel-powered 3 Series is one of those cars you really have to drive to believe. First off, its zero-to-60 mph time of 6.0 seconds is only four tenths slower than that of the category's gas-powered gold standard, BMW's 335i. For most buyers, that's a small price to pay for an increase in fuel economy of about 35% (the 335i is 17 city/26 highway mpg). Throw in all the driving feel and cornering ability that made the 3 Series a living legend, and you've got the greatest diesel car America's ever seen. 

2009 Toyota Highlander Hybrid | 26 mpg (27 city, 25 highway)
The Highlander Hybrid remains the most fuel-efficient three-row vehicle available today, earning it an automatic bid at the top of many families' shopping lists. On top of room for seven and exceptional fuel economy, the Highlander Hybrid offers proven reliability and the added all-weather confidence of standard all-wheel drive. 

2009 Chevrolet Silverado Hybrid | 21 mpg (21 city, 22 hwy)
If fuel economy is a major concern, then buying a truck doesn't make much sense. But what if you need the utility of a truck? Shouldn't you, too, be able to enjoy the benefits of hybrid technology? GM thinks so. That's why GM's Two-Mode hybrid system is available in the Chevy Silverado and GMC Sierra. Despite delivering up to a 50% improvement in city mpg, this pickup retains its essential truckness by offering nearly 1,500 pounds of payload capacity, a 6,100-pound tow rating and a big full size bed.