The move is a variation of Web-based protests against painful pump prices last year that asked motorists to avoid buying fuel on a certain day, and analysts said this one could have a similar effect at the pumps: unnoticeable.

"For the rest of the year, don't purchase any gasoline from the two biggest companies (which are now one) Exxon and Mobil," said the e-mail, signed by "Kerry Lyle" of the University of Alabama. A call to the university revealed no one of that name in the faculty, staff, or student body.

"This makes much more sense than the 'don't buy gas on a certain day' campaign," said the e-mail, which some Americans have circulated to their acquaintances and which has landed in several chat rooms on the Web.

The e-mail says such a boycott could force ExxonMobil to slash prices to attract customers back, triggering a gas war that may lower prices at other retailers too.

But analysts said that unless overall U.S. gasoline demand declines, or the price of crude oil slips, the boycott of one company would do little to bring down fuel prices.

"The primary reason for high gasoline prices is increased demand for energy around the world, particularly from China and India," said Mike Shanahan, spokesman for industry group the American Petroleum Institute.

"Crude oil costs money, refining it into gasoline costs money, transporting it and operating a service station costs money," he added.

ExxonMobil declined to comment.

U.S. retail gasoline prices struck a record average of $2.27 a gallon this week, bringing them about 28 percent higher than they were last year, according to the AAA motorist group's daily survey.

The higher gasoline prices follow a spike in the cost of crude to nearly $60 a barrel, continuing a prolonged rally on the back of surprising global demand growth.

While gasoline prices are at their highest ever in nominal terms, they remain below the inflation-adjusted peak of around $3 hit in the 1980s.

Skyrocketing prices may finally be having a dampening effect on U.S. consumer demand for energy, though it is too early to say for certain, the U.S. Energy Information Administration said this week.

"We may be discerning a bigger demand impact from prices, but it's too early to know definitely," said Doug MacIntyre, analyst for the EIA.

In the past two weeks, total energy demand amounted to 20.2 million barrels per day, down from 20.5 million barrels per day a year ago, according to the EIA.

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