He's shopping for a Chevy.
Tim Boyle/Getty Images
The fuel economy ratings system has changed since this man went shopping for a Chevy.

When you're shopping for a car, there are a lot of numbers to consider on the window sticker. Most people look at the car's price first, then let their eyes wander over to its horsepower and torque numbers. But with
gas prices hitting $4 a gallon in some areas,­
a lot more eyes are focusing on the car's fuel economy rating.

Fuel economy is a measure of how many miles a car can travel using a gallon of gasoline. Knowing a car's fuel economy is helpful to car buyers because it allows them to estimate the actual cost of ownership for a car. It's one thing if a car has a low sticker price, but week after week of paying lots of money just to keep the car rolling wears on most drivers. A car's fuel economy is measured by the federal government in a program run jointly by the Department of Energy and the Environmental Protection Agency (EPA).

The government measures fuel economy not only to help out consumers, but also to make sure that car companies are acting in the country's best interest. Having too many inefficient cars on the road is bad for the environment and the economy, since so much oil has to be imported.

Fuel Economy and Car Buying Trends
With the 2008 U.S. economy not starting out on the best foot, a lot of consumers are cutting back -- especially on car purchases. However, one type of car that's seeing a sales increase is small, fuel-efficient cars [source: U.S. News]. In fact, some consumers are even reporting that if gas gets much more expensive, they'll trade in their current cars for more fuel-efficient models [source: Cars.com].

The government has been estimating fuel economy on all cars and light trucks on U.S. roads since the 1960s, but for 2008, it revised its estimates. Why did the government make the change, and how will it affect you? Read on to find out.­

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