Hot fuel adds to cost of U.S. summer gasoline

By Janet McGurty

NEW YORK, May 22 (Reuters) - As if paying $4 a gallon isn't bad enough, U.S. drivers will soon face another gasoline price burden as the summer heat dilutes the amount of driving power delivered per gallon, industry watchdogs said on Thursday.

Drivers in most parts of the U.S. will likely get less energy than they pay for because fuel pumps at gas stations are unable to adjust prices to take into account the fuel volume changes caused by hot summer temperatures, they said.

"A 'hot fuel' surcharge of up a dime a gallon is concealed from motorists because they have no way to tell if the fuel they are buying is 60 degrees, 90 degrees or more," said Judy Dugan, research director of nonprofit Consumer Watchdog.

Gasoline is sold by volume, but as outside temperatures climb storage tanks heat up and fuel volume expands. That dilutes the amount of energy delivered per gallon, accounting for an extra $1.60 for each 20-gallon fill-up at 90 degrees based on current prices.

"It's the equivalent of the grocer putting his finger on the scale," said Dugan, who advocates legislation of requiring retail pumps to account for the temperature.

As mandated by law, retailers buy fuel from wholesalers by volume at 60 degrees Fahrenheit. But there is no requirement for the temperature at which they have to sell it.

"Adjusting fuel price to temperature is a matter of simple fairness," said Joan Claybrook, president of Public Citizen.

Technology to monitor temperature at pumps has been used for decades in Canada, where the oil industry pushed for the law.