Somebody has put sugar in the gas tank of knowledge about beating record fuel prices.

Bogus tips, some circulated by respected organizations, are circulating on the Internet and through the grapevine.

Heard the advice to pump fuel slowly to avoid vaporizing your purchase?

The thinking goes that, with the trigger fully depressed, a portion of the gas dispensed -- and paid for -- turns into a mist or gas as it streams into your tank and gets sucked back into the pumping equipment's air pollution control system.

Or there's the notion that it is best to fuel up early in the morning or late at night.

That way, gas is thickest, not thinned by the afternoon heat. You get more for your money.

This mis-guidance surfaced most recently in a news release this week from the respected AAA Mid-Atlantic.

But, as AAA acknowledged in a retraction sent to news organizations 45 minutes later, the advice is baseless.

Professor John Walz, head of Virginia Tech's chemical engineering department, said if pumping speed influences vaporization at all, the effect would be "extremely small." Hardly the kind of trick that is going to ease the pain at the pump.

In addition, even with his limited knowledge of fuel storage systems, he guessed that the gasoline that consumers purchase stays at a pretty constant temperature day and night in underground tanks. Buy at 6 a.m. or buy at 3 p.m., the temperature and the density should be about the same.

Also discredited was a tip to refill the tank before it falls below half to avoid evaporation.

Consumers asked at pumps in the Roanoke Valley said they were unaware of the bogus advice Friday. But some are benefiting from proven techniques that have endured since the fuel crisis of the 1970s, such as keeping speed down.

"It's making a difference," said Anne Cooney, who drives between her home in Boones Mill and her job in Roanoke County going no more than 55 or 60 on the interstate and four-lane roads where a faster speed is possible.

Also, it obviously pays to fuel up before the tank runs dry.

"Letting the car run out of gas is hard on the fuel pump. If motorists cannot afford to keep the tank half full," AAA Mid-Atlantic said, "then keeping the tank one-quarter full will keep the fuel pump submerged and running cooler." AAA notes that a new fuel pump costs $500 to $1,000.

However, the organization reported evidence that many motorists are not keeping a close enough eye on the needle.

Through May, calls to the AAA Mid-Atlantic roadside assistance line from out-of-gas motorists were 24 percent higher than during the same period last year.

This past week, AAA distributed a news release without checking its facts first.

Martha Meade, spokeswoman for AAA Mid-Atlantic and an advocate who issues a daily gas price report for the motoring public, said she failed to fact-check a release titled "Evaporating gas can cost precious pennies."

She declined to identify the source or explain how she learned it contained errors.

"It was my fault," she said. "Just like any other human being, we make mistakes."

AAA was not alone.

For instance, the bogus tips appear on the Web site of the New York Daily News and many online message boards.

Earlier this week, Ehow.com, a database of how-to articles that claims 8 million monthly visitors, was displaying the bogus gasoline tips on a page to which viewers gave five out of five stars.