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MPG is an extremely important factor when it comes to buying a new car. With the prices of gas these days, buying a gas-guzzler can end up costing you thousands more dollars in just a few short years. It’s essential to consider the long-term cost of owning your new vehicle, and unfortunately you’ll never have to stop paying for gas.

With all different types of vehicles, city MPG, highway MPG, and more, how do you compare them all to make sure you’re getting a good deal? Here are some tips and suggestions on how to compare MPG while you’re shopping for your new vehicle.

Check the Window Sticker

The Environmental Protection Agency (EPA) mandates all dealerships keep window stickers on cars that display fuel economy. While inspecting the sticker, you’ll see city MPG, highway MPG, and combined MPG. The highway MPG will always be highest, because in ideal conditions, driving at the same speed without braking or stopping will get you the best fuel economy. In reality, we drive in many different conditions. The combined MPG is a number that falls somewhere between city and highway MPG, and it’s a more accurate estimation of the fuel economy you can expect to get while driving. Whenever possible, use the combined MPG figures when comparing different cars.

Use the U.S. Department of Energy’s Website

The website FuelEconomy.gov is one of the best tools you can use to compare MPG and make sure you’re getting the best deal. With this site, you can look up any car and find out its EPA ratings. The best part about this is that the EPA made changes in 2008 that made it hard to compare pre-2008 vehicles’ MPG with post-2008 vehicles. This website standardizes it all for you, so that you can get an equalized comparison, which is very helpful if you’re considering a used car. Also, you can answer questions about your driving habits and get an estimate of the MPG you might be able to expect for your personal driving conditions.

New 2013 EPA Labels

If you’re purchasing a 2013 model-year car (or any new car in the future), you’ll have the benefit of seeing the new mandated EPA fuel economy labels. These newer labels will help you make closer comparisons between vehicles. The combined MPG will be the most prominent figure. It will also tell you how the vehicle compares to the average vehicle in its class in MPG. Most importantly, you’ll be able to see a figure that tells you how many gallons of gas you’ll need for every 100 miles. This figure is actually a much better way to compare vehicles than MPG.

Gallons per 100 Miles

Whenever possible, use gallons per 100 miles to compare vehicles. Here’s why: A car that gets 12.5 MPG uses 8 gallons to go 100 miles. A car that gets 25 MPG uses 4 gallons to go 100 miles. A car that gets 50 MPG uses 2 gallons to go 100 miles. As you can see, from 12.5 MPG to 25 MPG, you save 4 gallons per 100 miles, but from 25 MPG to 50 MPG, you only save 2 gallons per 100 miles. It shows that 50 MPG isn’t twice as good as 25 MPG as it would seem. Gallons per 100 miles will give you a better way to compare your gas savings between vehicles.

Daniel Smith is a father and mechanical engineer with Nissan auto who knows how important MPG can be because of rising gas prices. He loves to blog about cars and he often writes about anything from getting great deals on new cars to how to budget for gasoline.