Find the green car that is just right

Looking to reduce your carbon footprint? Your car is an obvious place to start. While standard, gas-fueled cars dominate the roads, there are a few current alternatives and some promising future technologies.

Investing in alternative fuel vehicles is not a no-brainer. The decision to buy a green car remains largely an ecological and political one, although there are some tangible advantages to do so.

The current popular and simplified reason to buy a car that emits less pollution is to prevent global climate change. However, efforts to clean up automotive emissions started as an attempt to address public health concerns by reducing smog. Gasoline-burning internal combustion engines release hydrocarbons, nitrogen oxide, carbon monoxide, and carbon dioxide into the atmosphere. Hydrocarbons and nitrogen oxide contributes to smog, while carbon monoxide is a poison in its own right. Most current automotive emissions controls are aimed at curbing these pollutants

Nitrogen oxide and carbon dioxide, specifically, contribute to global climate change. Currently, there are no laws limiting carbon dioxide emissions from cars, although California is attempting to implement regulations. For every gallon of gasoline burned, 19.6 pounds of carbon dioxide enter the atmosphere. Absent vehicle pollution controls, consumer choices are Americans' only tool for decreasing these automobile-generated carbon dioxide emissions.

For some, green cars offer another tangible benefit: lower costs at the pump. Because there is a direct relationship between fuel economy and carbon dioxide emissions, a car that produces less carbon dioxide will cost less to fill up, but the savings may not pan out over the lifetime of the car. Depending on the premium you pay for the green powertrain, you'll likely have to own your alternative fuel vehicle for many years to realize a cost saving. Depending on the cost of fuel, you may never see a fiscal advantage.

In this guide, we cover the current car options for people who want to reduce greenhouse gas and smog emissions. We also point out some future car technologies that may become viable in the next few years.

More green car resources from CNET