Motorists using the petrol station at Falkirk’s Morrisons are paying more than drivers using the firm’s outlets in Stirling and the Gyle.
But according to the company the differential - at a time when all petrol prices are predicted set to soar - is purely down to level of competition.
Some motorists have recently been annoyed to find the Falkirk outlet charging 121p per gallon while in Stirling it was 114p ... and just 110p at the Gyle in Edinburgh.
At the same time Tesco in Camelon were also charging 121p.
Morrisons are reluctant to go into any detail about how their pricing strategy operates, beyond arguing that prices set match local conditions.
But is competition so white hot in Stirling - or the Gyle - that Falkirk has to pay what some drivers argue amounts almost to a built-in surcharge for buying locally?
Morrisons says simply that it will not speculate on future pricing, but has confirmed that it does not offer any universal guide (eg an online guide) to what prices its branches are selling on any given day or month.
In what some will see as a postcode lottery the apparent “Falkirk factor” could be seen as a significant extra cost burden if it can be shown the area really is more expensive, month after month.
Rises at the end of 2017 mean that the cost of filling the tank of an average family car is now around £4 more than it was in July, when petrol and diesel were at their cheapest.
RAC fuel spokesman Simon Williams said: “Sadly, December was the month oil reached its highest point for over two and a half years – something which motorists are now feeling the effect of at the pumps.
“It’s hard to see pump prices getting much cheaper in the early part of 2018. “Unfortunately, the good times of lower cost fuel appear to be over.”