KAI RYSSDAL: We do business and the economy on this program, not physics. But sometimes the news is what the news is. So this next item is brought to you by the principle of thermal expansion. Heat any liquid, it expands. That includes the gas in the car you drive, which means the gallon you pay for at the pump might not be the gallon you get. That scientific truth is at the bottom of a consumer lawsuit filed this week as Marketplace's Dan Grech explains.
DAN GRECH: Gasoline is supposed to be sold at 60 degrees Fahrenheit. That's according to a century-old agreement between gas companies and regulators. Drivers in seven states accuse 17 oil companies and gas stations of breaking that promise. The consumer fraud lawsuit argues that stations sell warm gas in hot climates like Florida and Texas. Joan Claybrook's president of the consumer advocacy organization Public Citizen.
JOAN CLAYBROOK: The fuel, when it's warmer, expands so you're paying for a little bit more fuel than actually your getting into your tank in terms of energy.
Hot fuel ends up costing each driver a few extra cents per gallon.
CLAYBROOK: Pennies per person, but then if you drive a lot, it really does add up.
She says warm gas costs drivers $2 billion a year. John Bisney is a spokesman at the American Petroleum Institute.
JOHN BISNEY: There's no doubt that the science of that is accurate. It's really a cost-benefit question. It's just so minor that adjusting for it would just be cost prohibitive.
The prohibitive cost would come from stations having to install machines that adjust for warm gas either by keeping the gas cool or by compensating for its expansion. The worry is that those costs would likely be passed onto consumers. In New York, I'm Dan Grech for Marketplace.