How Green is Your Car?
What makes a car green? It's more than just its paint job. Choosing a green car is a more complex process than many realize. A hybrid badge slapped on a massive SUV does not automatically make the car planet-friendly. At the same, some sedans expel pollutants at a rate that would make a truck blush.
While it's a good place to start, gas mileage isn't the only issue to take into account when evaluating the effects of a car on the environment. Let's take a look at some of the main factors to consider when classifying a car as green.
When looking at the direct environmental impact of a vehicle, it's most logical to begin with its emissions. While cars produce a number of pollutants, the one that is generally focused on is carbon dioxide (CO2) since it's a greenhouse gas and contributes to global warming.
An excellent place to find information on the CO2 emissions of a particular vehicle is www.fueleconomy.gov, a site maintained jointly between the Environmental Protection Agency and the Department of Energy. The EPA also has a handy Green Vehicle Guide where you can look up emissions statistics, as well as check on what vehicles in your state have earned the EPA's "SmartWay" and even more exclusive "SmartWay Elite" designations. These are given to cars with low emissions and high fuel economy that earn high marks in the EPA's Air Pollution and Greenhouse scoring categories.
One important note to consider is that electric cars produce no direct emissions. Some critics of electric cars note that they get power from electricity derived from coal. However, even with this logic, they still produce considerably less CO2 than standard vehicles. A chart at treehugger.com shows an emissions comparison between conventional, hybrid-electric and plug-in hybrid-electric vehicles. The emissions produced by electric cars depends greatly on their source of electricity.
Some also point to ethanol as a way to reduce CO2 emissions from cars. The benefits of ethanol are widely-debated. In some ways it works as a cycle: the crops that the ethanol is derived from soak up CO2 during their lifecycle. This CO2 is then dispersed back into the atmosphere when a car burns the ethanol fuel. Unfortunately, this view ignores the significant emissions released in the production of ethanol. Yahoo cites a study done at the University of California at Berkeley where researchers "concluded that using ethanol made from corn instead of gasoline would lead to a moderate 13 percent reduction in greenhouse emissions."