MADISON, Wis. (3/16/11)--Here we go again: Gas prices are on the rise, with growth at a near-record pace of 33 cents a gallon during the past two weeks (Lundberg Survey Inc.
March 6). As a result, fuel-efficiency has once more risen to the top of car-shoppers's concerns. So now is a good time to re-examine the standard measure of efficiency--the good old "miles per gallon" (mpg)--because now there's a better way to tell a sipper from a guzzler, according to editors from the Credit Union National Association's Center for Personal Finance. Consider which of two car buyers will cut fuel costs more: Reggie, who replaces his old 16-mpg Chevy Silverado with a new 25-mpg Ford Fusion? Or Diane, who replaces her old 27-mpg Honda Civic with a new 50-mpg Toyota Prius? If you say Diane, you would be mistaken. Reggie's relatively meager 9 mpg mileage increase represents a greater reduction in fuel consumption than Diane's improvement of 23 mpg. You can't see that easily from the mpg figures. But look what becomes clear when you turn mileage upside down--flipping mpg to gpm--by calculating the gallons of gasoline each car burns to travel 100 miles: 100 divided by miles driven per gallon = gallons used per 100 miles
Comparing two cars' fuel consumption in gallons per 100 miles makes it easy to see improvement in gas use. Here's how much more Reggie will save for every 100 miles he drives, at the national average price, according to AAA, of $3.509 for a gallon of regular gasoline:
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And the advantage piles up. For every 10,000 miles driven, Reggie will realize savings of $790 to Diane's $597--a difference of $193. Of course, Reggie would do even better by buying a car like Diane's, but let's not ask too much of him all at once. The fact is that the greatest savings come from even modest improvements in the fuel consumption of the least efficient cars on the road. For different looks at fuel efficiency, read "Why You Might Want a Small Euro Car" and "Cars Are Plugged In and (Almost) Ready to Go" in the Home & Family Finance Resource Center