Fuel consumption calculators

Last July, with gas prices soaring, we covered a study that showed how mpg numbers for fuel economy often mislead consumers and cause them to make poor decisions. (See our original posting, “Not all mpgs are created equal.”)

Now the Duke University professors who did the original study have published online calculators to help you see the real effect of choosing a particular car with higher or lower gas mileage. The bottom line is, high-mileage cars are a game of diminishing returns. You get more bang for your buck improving the mileage of poor performing cars than by replacing a car with good mileage with one that gets a really impressive mpg number.

Try the calculators yourself at www.mpgillusion.com. A couple of notes: You need the latest Flash player to see the calculators. And once you get there, you can’t find fuel consumption figures for ranges of less than 100 miles. Still, computing fuel consumption from mpg isn’t easy in your head. So these calculators are a good starting point to understand the effects of improving gas mileage.

You can find fuel economy test results in our New Car Selector and on individual model pages, accessed through our A-Z index or the pulldown menus on major ConsumerReports.org Cars pages.

—Eric Evarts