Gas Mileage Calculations: Why MPG Numbers Really Matter

Gas mileage calculations have recently changed to more accurately reflect real-world mpg. Here’s what you need to know about the new math and how to improve your mpg, save money and reduce air pollution.

We drive much more than 55: Today’s speed limits are much higher than those of 1985, when the EPA last revised its mpg math.
We drive much more than 55: Today’s speed limits are much higher than those of 1985, when the EPA last revised its mpg math.
Photo by Istockphoto/Harris Shiffman