Duke University researchers say thinking gallons/mile rather than miles/gallon gives a person a much clearer picture of fuel savings.

There is a math illusion here,” said Richard Larrick, a management professor at Duke University, whose research appears in the journal Science.

Larrick said most people think improvements in miles per gallon are all the same, where a 5 gallon per mile improvement would yield the same gas savings in a car that gets 10 miles per gallon or 20 miles per gallon. (One mile equals 1.61 kilometers, and one U.S. gallon equals 3.79 liters.)

“The reality that few people appreciate is that improving fuel efficiency from 10 to 20 miles per gallon is actually a more significant savings than improving from 25 to 50 miles per gallon for the same distance of driving,” Larrick said.

Larrick experimented on college students, giving them a small test of car choices with fuel efficiency expressed in miles/gallon. Students had problems determining the greatest gain in fuel efficiency.

When he turned it around to gallons/mile, the change in fuel efficiency was obvious

To help you out, here’s a conversion table Larrick’s team developed.

29 years ago, then President, Jimmy Carter, told Americans the energy crisis was:

“a clear and present danger to our nation” and drew out a plan to address it.

Listen here to today’s story:

He was so ahead of his time.

Well, not quite yet, but truckers are backing a 65 mph speed limit.

Con-Way Freight, a national biggie, has announce they have turned the electronic speed limiters to 62 mpg. Con-Way figures that will save them 3.2 millions of diesel/year. Sure mounts up when fuel prices are in the neighborhood of $4/gal.

American Trucking Association says 65 mpg is not only a matter of cost saving, but also safety.

Every 1-mph reduction in speed results in 0.1 increase in fuel efficiency.

This sounds good on paper, but as our 90-yr old grandma in Michigan told us years ago (yes she is still driving), you just can’t get anywhere at 55 mph.

Scheduled to begin Sept. next year, the Progressive Automotive X Prize competition will award $10 million to the first team that can build and bring to market a car that gets 100 mpg. It’s international, so no downsizing the field.

Some of the contestants were shown at the NY International Auto Show. No major US auto company has announced it would compete. VW says it has been there, done that. Honda thinks that the 62 mpg for its hydrogen fuel-cell car is pretty darn good.

“We need a car that is not just a concept but can be made in mass quantities at a reasonable cost for the average American,” says Jack Hidary, chairman of the Coalition Advocating for Smart Transportation and a donor to the X Prize’s new effort. “Unfortunately, Detroit has not stepped up to the plate, they have fought CAFE [Corporate Average Fuel Economy] standards every step of the way.”

60 teams from 9 countries have entered the competition, including high school and college students. Sounds like some serious thinking outside the box is going on here.

In Europe these problems are not just hypothetical. Here are some small, neat cars that are fun to drive.

Fiat 500 - 36 mpg 0-60 in 9.5 seconds.

European Ford Fiesta(not the one formerly sold in the US) - 63 mpg with the diesel engine. Bring ‘em on home, boys!

Ford Kuga (no relation to Cougar) SUV - 30 mpg

Renault Twingo - clean emissions and economy