The last time a driver on a UK motorway filled a full tank, the £100 note stayed in the wallet. That changes this weekend. The RAC says the average price of petrol has climbed above 160p a litre, the highest since the Iran war began and, on the Guardian’s count on Friday, the highest level in almost four years. Diesel sits at roughly 182p, meaning a full tank for the average diesel family car is back at £100 for the first time since early June, the motoring group’s head of policy Simon Williams told the BBC.
The Guardian’s reporting lands the timing squarely on the August bank holiday getaway, when millions of cars take to roads that are already the most expensive they have been since 2022. Williams pointed to the diplomatic channel as the exit: pump prices should come back down if talks succeed in re-opening the Strait of Hormuz, the narrow waterway whose disruption has kept the oil market nervous since February, when US and Israeli strikes on Iran triggered the supply shock in the first place. A House of Commons Library briefing dates the initial damage at 12p a litre on petrol and 25p on diesel across the first three weeks of March alone.
There is a second price rise queued behind the first one, and it is domestic. The longstanding 5p cut in fuel duty ends on 31 August, replaced by a 1p increase from September and the remainder phased in through stages before March 2027, as set out in the Spring Forecast. So even if the tanker market behaves perfectly, the pump adjusts upward by policy, not by war. The RAC’s arithmetic makes the interaction bluntly clear: petrol has already climbed from its early-July low of 150.59p, and diesel has not yet recovered to its April peak of 191.54p, which means both numbers have a ceiling above them and a floor beneath them that did not exist in June.
For businesses with vans and fleets, the effect is immediate and unforgiving. Fuel is the one cost line a small haulier cannot negotiate, hedge or defer, and a bank holiday spike lands in the same fortnight as the duty change. Delivery firms and trades that priced their jobs in July are now finishing them at August costs.
The political dimension writes itself, which is presumably why the coverage leads with the note in the wallet. Four-year highs have a way of outlasting whatever caused them in the public memory. If Hormuz opens and barrels fall, drivers will notice the relief. If it does not, they will be doing the same maths the RAC is doing, tank by tank, and the duty change will look less like a footnote and more like a second pinch. The queue at the pump, for now, is where Britain’s inflation mood gets measured in ones.