I think your reliance on the average makes a little sense for estimating the amount of "over charging"

Why not? As an overall nationwide picture, I can't think of a reason why it wouldn't be a good method, but maybe you have.

Locally, it could make a big difference. That is someone in the desert southwest could be getting hosed while someone in Alaska might benefit. At least in theory.

Jim,

Gasoline prices tend to track air temperature these days, so with higher prices when the gas is warmer you get more of an effect. The thing that is a little furstrating about the average is that it is not reported with a standard deviation so it is not possible to back out the range of temperatures measured. The main point of the original article, that prices will compensate if fuel temperature is taken into account is a good one. I think that some of these suits will succeed and then we'll either see temperature compensation or disclosure and that will be the end of it.