Ethanol, biodiesel and electricity have seen more attention and investment, but when natural gas cost almost half that of $4 per gallon gasoline this summer, the fuel's long-term viability took a second turn.

Toyota tried in the United States, along with Honda, Ford, GM and Chrysler, to sell compressed natural gas-powered cars to fleets and a few private individuals. All failed except Honda, which continues to sell its CNG Civic GX sedan to private customers in California and New York, albeit in very small numbers.

Now Toyota is back nine years later with a second CNG Camry, this time as a lowered and grill-less hybrid. Toyota claims a range of 250 miles from an eight-gallon equivalent of natural gas, and estimated mileage is roughly the same as a regular Camry Hybrid at 32/33.