KANSAS CITY -- Three companies with thousands of retail fuel pumps have agreed to settle lawsuits accusing them of shorting consumers with "hot fuel" - gasoline and diesel fuel sold without adjusting its volume for temperature.

Attorneys for Wal-Mart and its Sams Club subsidiary, along with Valero Energy Corp. and Caseys General Stores Inc., told the U.S. District Court in Kansas City, Kan., that each has reached an "enforceable settlement agreement" with the plaintiffs, according to orders posted by the courts chief judge, Kathryn Vratil.

Vratil still has to approve the settlements, but if she does they will apply to dozens of hot-fuel lawsuits filed across the country, including in Kansas and Missouri.

The Kansas City Star, which has been probing the hot fuel issue for a half-dozen years, estimates hot fuel costs consumers roughly $3.5 billion annually.

Gasoline and diesel fuel expands in warmer months, so a gallon of fuel contains less energy than what consumers pay for at the pump. Hence, the basis for the lawsuits and the term "hot fuel."

Earlier last month, BP Products North America Inc., ConocoPhillips Co. and Shell Oil Products U.S. reached hot-fuel settlements, although details were not disclosed. (See May 1 Bus & Motorcoach News.)

Details of the Wal-Mart, Valero and Caseys settlements also were not disclosed, but observers say they could further advance the day when fuel pumps in the U.S. start adjusting for hot fuel. Those three companies own all or some of their stores that sell fuel.

Judy Dugan, research director for Consumer Watchdog, a California public interest group, said that selling fuel in a fair manner by adjusting it for temperature appeared to be nearer, at least in some locations.

But Dan Gilligan, president of the Petroleum Marketers Association of America, which represents retailers, said his group remained firmly opposed to temperature-adjusted fuel and would continue to fight it. The association has maintained that the switch wont be worth it, weighing the cost of switching pumps against the scope of the problem.

"Its just not cost effective," he said.

A Valero subsidiary already sells temperature-adjusted fuel in Canada, where it has been done for decades. The oil industry, which has been reluctant to discuss the idea for the U.S., embraced it in Canada since "cold fuel" cost them money there.

The volume of fuel is pegged to a 60-degree standard, at which the 231-cubic-inch American gallon puts out a certain amount of energy. If the temperature of that gasoline rises to 90 degrees, though, it expands to more than 235 cubic inches - but a gallon still gives the consumer 231 cubic inches, which at the higher temperature contains less energy.