CHATTANOOGA, Tenn. -- Rosemary Andersen of Andersen Flaps says she was as surprised as anybody to learn that their "EcoFlaps" actually conserve fuel.

She knew they cut down splash and spray and make driving safer generally, but to actually cut diesel consumption? "Who would have thought that mud flaps flapping around would have caused so much wind resistance?" she told Today's Trucking. "Turns out it's huge."

The thing is, EcoFlaps are perforated so they don't flop around. And that's one of the reasons they don't splash much. But some recent lab tests proved that they improve mileage, considerably, so the Andersens are making a flap about the discovery.

They've also just signed on a Canadian distributor for the product.

Here's the dirt on the flap's fuel-saving properties. In 2006, the Transportation Research Center Inc. (TRC) performed SAE Test J1321 Type II on the Andersen flaps.

The full results are on the EcoFlap website, but basically, the baseline fuel economy for the two test trucks was 6.37 mpg and 6.54 mpg before the flaps grew to 6.71 mpg and 6.77 mpg respectively with them installed.

According to the company website: "The patented airflow design of EcoFlaps saves an average of $1,500 in fuel per year for individual trucks, which translates to super savings for you and our environment."

Are we buying the story? We're not sure but we wouldn't be the first. For one thing they're flipping off the shelves. Andersen's building not one, but two new production facilities. Also, the American carrier Arctic Express just ordered $20,000 worth. You read that right, that's 20Gs worth of mudflaps.

An article in Business First magazine last year quoted Arctic's CEO Richard Durst thusly: "With fuel at $4.70 a gallon, these were worth another look."

That was then -- when Prius' were jumping off the shelves and people were parking their Escalades. Now, diesel prices are down to half of what they were last summer and frankly, it's hard to get pumped about saving fuel.

It shouldn't be that way, argues Jack Lee, the president and CEO of Vancouver-based fuel consultants 4ReFuel Inc. "A reliable fuel management system can save you up to 20 percent on your fuel costs," he says. "So no matter what fuel prices do, you can always exert more control over your fuel costs."

Of course, the bigger you are, the more you stand to gain. If you purchase $100,000 worth of fuel every year and invest in some technology or practice that yields just a one-percent improvement in economy, you'll save $1,000. On the other hand, if you buy $1 million a year and save a single percent, you're talking $10 grand.