The lawsuit, filed by a group of truckers and other drivers, alleges that consumers are being hosed at the fuel pump because prices are not adjusted to account for temperature swings. District Court Judge Kathryn H. Vratil allowed the case to proceed.

Plaintiffs in the "hot fuel" case say that during wholesale transactions, a gallon of fuel is defined by fuel companies as 231 cubic inches at 60 degrees. At retail, however, there is no consideration given for temperature. Studies have shown that national average temperature of motor fuel is near 70 degrees, and even higher in warmer weather.

Plaintiffs contend that fuel companies are profiting on "extra" gallons crated by the expansion. A U.S. House Committee on Oversight and Government Reform subcommittee study of 2006 data showed that hot fuel nationwide costs consumers an extra $2.3 billion per year.

The oil companies and gas retailers argue, however, that state regulations and industry standards define a gallon of gasoline by volume, not in terms of its energy output, Associated Press reports. As long as the customer receives 231 cubic inches of fuel the customer is getting what they paid for, they insist.

The plaintiffs and advocacy groups like OOIDA want the U.S. Department of Weights and Measures to require fuel retailers in all 50 states to install the devices as a solution to the hot fuel problem.

The industry says the cost of installing temperature adjustment equipment would be prohibitive. But the plaintiffs point out that the petroleum industry has pushed for using these adjustments in Canada, the government gave oil firms permission to install output volume adjustment devices to offset profits lost to colder temperatures.