In the market for a new car? Now is your opportunity to change your carbon impact. Even if you're not looking yet, keep reading. The car market is changing and, the sooner you understand the changes, the better off you'll be the next time you venture onto the sales lot.

The average age of a car in the US is 9 years, which means that buying a car is kind of like getting a fixed-rate mortgage. The typical car buyer is basically locking in their carbon production rates for the next nine years. And cars and light trucks account for about two thirds of transportation-related U.S. greenhouse gas emissions.

Car buying tips:

  • You'll likely own this car for several years, so make your next purchase with fuel economy in mind so you can reap the benefits for a long time.
  • Look at fueleconomy.gov to compare the fuel economy of different cars you're considering. Even in the same class (e.g. midsize, fullsize, SUV, etc.), the fuel economies of different makes and models vary significantly.
  • Consider the car you need for most trips you take. If you need hauling capability or higher capacity only once in a while, you'll save gas money and lower your impact the rest of the year by renting on those occasions.
  • Considering a hybrid? Look for one that gets better fuel economy than other cars in its class. Sounds like a no-brainer but some hybrids use the advanced technology to max out performance, not fuel efficiency.
  • If you're in a location where high-blend ethanol (E85) is readily available, consider buying a flex-fuel car. Many new cars are actually flex fuel but are not marketed as such. Ask your dealer for more info.
  • Car sharing? Consider joining a car-sharing program if you live in a highly populated area and don't need a car every day.

In addition to contributing significantly to global warming pollution, cars also absorb a tremendous amount of American's incomes. For most families, transportation ranks as the second highest household expenditure. But help for saving money on gas is already on the show-room floor: The most fuel-efficient conventional gasoline cars get up to 40 miles per gallon, while carefully driven hybrids can top 60. The problem is, for every car with reasonable mileage there are a lot of guzzlers. The average fuel economy of 2006 model year cars was only 25.4 mpg. We can do a lot better, and it begins with making good decisions on the lot.

The auto industry has poured hundreds of millions of dollars into marketing and consumer research, and they know how to push consumer buttons. Many auto manufacturers play down efficiency and talk up style, mobility, comfort, and navigation systems. Remember, though, that ultimately the consumer is king and all the information you want and need to make an informed decision on fuel economy and environmental attributes of various car types can be made available to you if you ask. So if you go in prepared, you can make the system work for you. And if a dealer can't answer your questions, try another dealer. Choices abound in the competitive automobile marketplace.

In general, two things will determine the climate impact of the car you choose: its fuel efficiency and how much you drive it. That's why you should look long and hard at how you use the car. The more objectively you assess your needs, the better your decision will be.

Other car options? You might be wondering if there is an option other than purchasing a gasoline car. See our story about alternative fuels and alternative fuel vehicles. There are a few gasoline alternatives like ethanol and natural gas but an even brighter alternative fuel future is on the horizon. If you are looking for alternative fuel options, you can search using this map.

Car sharing? If you only need a car once in a while and live in a highly populated area, one of the best new options in the American transportation market is to participate in a car-sharing program. You pay a small monthly or annual fee that gives you the privilege to use a shared car when you need it. You reserve and pay online, pick the type of car you need (maybe a pick-up if you're buying new furniture or a sedan for grocery shopping), and go to the neighborhood spot where the car is waiting. Car sharing is usually rather inexpensive because you are only one of many people sharing the cost of the car. It's a good way to optimize the utilization of a car that, if owned by an individual, would mostly sit idle in the parking lot. You can also save money by not having to pay registration and maintenance on a seldom used car. Wondering if your city has it? See http://www.carsharing.net/where.html

Feeling hybrid? No question you'll like the fuel cost. What's more surprising is how much you might like the driving experience. The overall engineering is top notch, and the instrument panel, which gives a real-time reading of fuel efficiency, has spurred a whole new class of drivers called hypermilers. Their goal is to amaze their friends and stun their family with outrageous tales of how long they go between fill-ups. If you're looking for climate protection bang, not all hybrids are created equal. Some manufacturers are looking to cash in on the hybrid cache but are actually using the advanced technology to max out performance, not efficiency. Another bummer: Toyota has been so successful with its hybrids that the federal tax credit allotted to them is shrinking.

Got diesel? Forget every bad smelling diesel experience and welcome efficiency that rivals some hybrids. Common rail diesel, as the technology is called, is widespread in Europe and making inroads here. It's cleaner than any diesel you've experienced and can also run biodiesel. What makes the biodiesel community unique is that they are often engaged in procuring fuel close to home through recycling waste oil and supporting local farmers. Still, untreated diesel exhaust is toxic and smog-causing and some states won't allow sale of new diesel passenger cars until the manufacturers lower the emissions further.