Study questions method of listing fuel efficiency
Listing vehicle fuel efficiency in "gallons per mile" instead "miles per gallon" would allow consumers to better understand potential fuel savings when they shop for a new car, according to a study released today.
The Duke University study, published in Science magazine, says listing fuel efficiency in its current form leads consumers to assume fuel consumption drops at an even rate as efficiency improves. It doesn't.
Jack Soll, a management professor at the university's Fuqua School of Business and co-author of the study, said the greatest fuel savings are drawn from improving less efficient cars and trucks. "When fuel efficiency is expressed as gallons per 100 miles, it becomes clear which combination of cars will save a family the most gas," he said.
Replacing a large vehicle that gets 10 mpg with one that gets 20 mpg reduces gas consumption over 100 miles from 10 gallons to five. But replacing a small vehicle that gets 25 mpg with one that gets 50 mpg reduces gas use per 100 miles from four gallons to two.
The authors are urging consumer publications and automakers to list efficiency in terms of gallons per 10,000 miles driven.
"There are significant savings to be had by improving efficiency by even 2 or 3 miles per gallon on inefficient cars," said Richard Larrick, the study's co-author. "But because we communicate in miles per gallon, that savings is not immediately evident to consumers."