WASHINGTON, D.C. --- Nine of the top 10 vehicles in the government's fuel economy rankings for the 2010 model year are hybrids, and the Toyota Prius again tops the list. 

Two vehicles, the Ford Fusion Hybrid FWD and the Mercury Milan Hybrid FWD, tied for second place.

The only non-hybrid at the top of the list was Daimler's Smart fortwo. 

Meanwhile, the EPA is still trying to figure out how to measure fuel economy and greenhouse gas emissions in electric cars and plug-in hybrids in a manner that will help consumers make comparisons with traditional gasoline- and diesel-powered vehicles. Such vehicles, including the Tesla Roadster, were excluded from the fuel-economy leaders list. 

Here is the top 10 list of fuel economy leaders for MY 2010: 

1.  Toyota Prius (hybrid) -- 51 mpg city/48 highway

2.  Ford Fusion Hybrid FWD -- 41/36

2.   Mercury Milan Hybrid FWD -- 41/36

3.   Honda Civic Hybrid -- 40/45

4.   Honda Insight (hybrid) -- 40/43

5.   Lexus HS250h (hybrid) -- 35/34

6.   Nissan Altima Hybrid -- 35/33

7.   Ford Escape Hybrid FWD -- 34/31

7.   Mazda Tribute Hybrid 2WD -- 34/31

7.   Mercury Mariner Hybrid FWD -- 34/31

8.   Smart fortwo Cabriolet (automatic) -- 33/41

8.   Smart fortwo Coupe (automatic) -- 33/41

9.   Toyota Camry Hybrid -- 33/34

10. Lexus RX450h (hybrid, 2WD) -- 32/28