With gasoline prices soaring above $3 a gallon, and with midday temperatures flying north of 100 degrees Fahrenheit, consumer advocates are reminding drivers about an old trick that can save a few pennies a fill-up — do it early in the morning when temperatures are lowest.
Fuel, like all liquids, expands when heated and contracts with cooled. Therefore, when motorists fill their tanks when the fuel is cooler, they will get a little more volume for the same amount of money. Motorists who fill up during the hottest part of the day get a little less volume, and therefore a little less energy in their tanks.
The difference isn’t much. The Arizona Department of Weights and Measures, which regulates filling station metering, says the impact amounts to just a few tablespoons of fuel per fill-up. But over time the difference adds up — especially as the price of gasoline rises. Published reports have placed the loss to Arizona consumers at more than $115 million a year. And hot gas overcharging amounts to a $50 tax on every car in the country, according to the Owner-Operator Independent Drivers Association Foundation.
The issue has been debated for decades, but with gasoline prices so high, con- sumer groups have launched new efforts to require service stations to install measuring equipment on their pumps that compensates for temperature differences. In December, truck drivers and motorists in seven states, including Arizona, filed two lawsuits against 22 oil companies and gasoline and diesel retailers alleging they are overcharging customers more than $2 billion nationwide for overheated fuel.
The suits targeted “a system that has been quietly picking money from the pockets of citizens throughout the country,” said Joan Claybrook, president of the Public Citizen consumer advocacy group, who participated in a news conference announcing the suit.
The litigation asks for financial compensation and the installation of temperature-correcting equipment on gasoline and diesel pumps.
Also, Public Citizen has been lobbying Congress to protect consumers from hot-fuel overcharging.
But the oil industry has long resisted efforts to require temperature compensation at the pump. Opponents say the equipment would cost a couple of thousand dollars a pump. They say the added expense would have to be passed on to consumers — more than offsetting any savings from more precise measuring.
Gas stations in Canada do use temperature compensated meters to adjust fuel deliveries, but there the situation favors the oil companies and works against consumers, tending to deliver smaller volumes of fuel because the temperature is cold for much of the year.
Steve Meissner, spokesman for the Arizona Department of Weights and Measures, said the agency believes hot gas is a real problem in Arizona. But officials have not yet figured out the best way to deal with the issue in a way that helps consumers, he said.
One possibility might be to follow a model used in Hawaii, a state with very high gasoline prices. Weights and measures officials there tested fuel tank temperatures and decided that a gallon of gasoline delivered by fuel pumps should contain 234 cubic inches of fuel rather than the industry standard of 231 cubic inches. That change compensates for average temperature variations.
The system works well in Hawaii because temperatures around the state are relatively uniform, Meissner said. It would be tougher to implement in Arizona because of wide temperature variations between such locations as Flagstaff and Yuma, he said. But he said Arizona could be divided into regions that could have their own volume standards, he said.
Meissner said state inspectors have started taking measurements of gasoline temperatures at service stations to establish baseline information about tank temperatures in Arizona.
“But we’ve only been doing it for four or five months, and you need 12 months for a definitive database,” he said. “We are in the study and discussion phase.”