Each year, the American Council for an Energy-Efficient Economy (ACEEE) puts out its list of the 12 "greenest cars," taking into account tailpipe emissions, gas mileage, and curb weight. Here is our photo gallery of this year's greenest 12.
The Civic GX comes in as the ACEEE's greenest car, largely due to the fact it runs on natural gas, which gives off fewer smog-producing pollutants and greenhouse gases than gasoline-powered cars. The Civic GX uses a 1.8-liter four-cylinder engine that gets 24 mpg in the city and 36 mpg on the highway, and is rated as an Advanced Technology Partial Zero Emissions Vehicle by the California Air Resources Board.
The granddaddy of hybrid cars, the Prius uses a parallel electric powertrain to recycle kinetic energy that would otherwise be wasted, turning it back into motive energy for the car. It can drive under electric power alone at low speeds, or use its 1.5-liter four-cylinder engine. The Prius is rated at 48 mpg city and 45 mpg highway by the EPA, and is classified as an Advanced Technology Partial Zero Emissions Vehicle by the California Air Resources Board.
Honda's hybrid car uses a less robust electric system than the Toyota Prius, but the Civic's small, 1.3-liter four-cylinder engine gives it excellent economy and low emissions. Its fuel economy is 40 mpg in the city and 45 mpg on the highway, as rated by the EPA. The California Air Resources Board rates it as a Advanced Technology Partial Zero Emissions Vehicle.
The Smart ForTwo makes its first appearance on this list, as it has just been introduced in the U.S. It scores for its very economical 1-liter engine and electronic clutch transmission, giving it 33 mpg city and 41 mpg highway. For emissions, it gets a Ultra Low Emissions Vehicle rating from the California Air Resources Board, not as good as others on this list, but the good fuel economy means low greenhouse gas emissions.
The Yaris makes the green list for its exceptional fuel economy, as its 1.5-liter four-cylinder engine doesn't use advanced technology beyond variable valve timing and efficient tuning. This tuning gets it 29 mpg in the city and 36 mpg on the highway, and an Ultra Low Emissions Vehicle rating from the California Air Resources Board.
Nissan's first hybrid makes use of a system based on Toyota's hybrid technology, with a parallel electric powertrain. This system is paired with a larger gas engine than many other cars on this list, a 2.5-liter four cylinder. But even with this big engine, it still pulls in mileage numbers of 35 mpg city and 33 mpg highway and is rated as an Advanced Technology Partial Zero Emissions Vehicle by the California Air Resources Board.
The Corolla is another car that makes it on the greenest list, due to its efficient engine rather than any use of advanced technology. The Corolla's 1.8-liter four-cylinder engine gets an EPA-rated 28 mpg in the city and 37 mpg on the highway, while its emissions give it an Ultra Low Emissions Vehicle rating from the California Air Resources Board.
The Mini's appearance on this list shows that green doesn't have to equal boring, although this is the standard Cooper and not the turbocharged S version. The Cooper and the Cooper Clubman are powered by a 1.6-liter four-cylinder engine, getting 28 mpg city and 37 mpg highway. Emission levels aren't the best, merely meeting the Low Emission Vehicle requirement of California's Air Resources Board.
Ford offers the only car from a U.S. company to make it on the list. The Focus runs an efficient 2-liter four-cylinder engine, giving it 24 mpg city and 35 mpg on the highway. But more impressively, its smog-producing emissions are so low it earns a Partial Zero Emissions Vehicle rating from the California Air Resources Board.
Similar to the Nissan Altima Hybrid, the Camry Hybrid is a medium-size sedan with one of the larger engines among the cars on this list. But the size of the engine is mitigated by the full hybrid system, which gives it 33 mpg city and 34 mpg highway. It also earns an excellent Advanced Technology Partial Zero Emissions Vehicle rating from the California Air Resources Board.
Honda's Civic makes its third appearance on this list in standard gasoline form. Although not as green as the natural gas or hybrid versions, the regular car still gets 26 mpg in the city and 34 mpg on the highway. For emissions, it gets an Ultra Low Emissions Vehicle rating from the California Air Resources Board. It's powered by a 1.8-liter four-cylinder engine.
Honda rounds out the greenest cars list with its smallest car, the Fit. This standard gasoline-fueled car uses a 1.5-liter four-cylinder engine to get 28 mpg city and 34 mpg highway. The emissions rating is a less-impressive Low Emissions Vehicle from the California Air Resources Board.