When you're looking into buying a new vehicle, it's a good thing you have gas mileage ratings to help you decide. There are so many factors that go into your decision-type of vehicle, make, model, and what type of features you want. Nobody paid much attention to fuel economy 10 or 20 years ago, but now it's become another important factor in buying a new vehicle. With uncertain and constantly fluctuating gas prices, people are realizing how much money a fuel-efficient vehicle saves them.

The U.S. Department of Energy (DOE) and the U.S. Environmental Protection Agency (EPA) jointly publish a book of gas mileage ratings called the Fuel Economy Guide each year for new vehicles. Don't neglect this important resource when shopping for a new vehicle. This booklet is free to download. Just perform an Internet search for "gas mileage ratings" or navigate to http://www.fueleconomy.gov/ to locate the booklet.

Ever notice those stickers on the windows of new cars that list the vehicle's average miles per gallon (MPG) in the city and on the highway? Those stickers are mandated by the DOE and the EPA. That information and more can be found in the Fuel Economy Guide. These gas mileage ratings are based on laboratory testing, which is then adjusted for real-world driving conditions and typical use by real people on the road.

The Fuel Economy Guide also provides estimated annual fuel cost estimates for each vehicle, multiplying the average number of yearly city and highway miles driven by the projected cost of unleaded gasoline for the year. Of course, these estimates are only averages and your actual fuel costs will differ. How you drive, how you maintain your vehicle, and what type of climate and terrain you drive in will all affect your gas mileage rating. In addition, the price of gas may fluctuate unexpectedly. Nevertheless, having an average gas mileage rating in the Fuel Economy Guide makes a big difference when you're evaluating the fuel economy of different kinds of vehicles.

The Fuel Economy Guide divides vehicles into classes, making it easier to compare gas mileage ratings. For example, comparing the average number of MPG of a minivan versus the average MPG of a small sedan is not going to do you much good; comparing vehicle of the same class against each other will ultimately be most helpful. A table of the fuel economy ranges of each vehicle class is also helpful, so that you can see the lowest and highest efficiency vehicles in each class.

Don't underestimate the importance of fuel economy! See how your dream car measures up against current gas mileage ratings. You could save hundreds of dollars each year by choosing a smarter, more fuel-efficient vehicle.