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UK petrol prices rose by 7.7p per litre between August and September 2026, while diesel rose by 9.8p per litre, according to the Department for Energy Security and Net Zero. The Government is not powerless: it can change fuel duty and scrutinise how the market operates. But it cannot set global oil prices, and the available figures do not show how much a new intervention would cut pump prices or how quickly.
How much did petrol prices rise?
The Department for Energy Security and Net Zero reported that the average petrol price increased by 7.7p per litre from August to September 2026. Diesel increased by 9.8p per litre over the same month-to-month comparison. These figures describe the change between those two months; they are not year-on-year comparisons. Department for Energy Security and Net Zero: September 2026 fuel prices
The figures establish the scale of the monthly increase, but do not break down what caused September’s rise. The latest weekly value is not included in the official-page text available here, so it would be misleading to supply a number for the week commencing 28 September.
What is happening to fuel duty?
HMRC’s May 2026 notice says the temporary 5p-per-litre cut in unleaded petrol duty was extended through 31 December 2026. That is a reduction in the duty rate, not a guarantee that each forecourt’s pump price is exactly 5p lower: pump prices also reflect other costs and market conditions. HMRC: fuel duty rates and temporary cut
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The same notice described default duty rises from January and March 2027, with final rates to be confirmed at Budget 2026. This is the position set out in that notice; it should not be read as confirmation that the proposed path remained unchanged after later announcements.
Why global wholesale prices matter
Petrol’s pump price is not made up of fuel duty alone. Wholesale costs, including the cost of crude oil, are influenced by international markets, which the UK Government does not directly control. A May 2026 government road-fuel monitoring report illustrates the distinction: over the report’s analysis period, petrol rose by 25.9p per litre since the beginning of the Middle East conflict, and the report attributed 10.3p of that rise to crude oil. Department for Energy Security and Net Zero: May 2026 road-fuel monitoring report
Those figures apply to the report’s conflict-related period, not to the separate 7.7p increase between August and September. They cannot be used as a breakdown of September’s rise.
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1Fix the driver behind crashes, sound loss and screen glitches2Clear out junk files and repair common Windows errors3Scan for outdated or missing drivers - takes under a minuteHow much can the Government do?
“Little the Government can do” is too absolute. Ministers can change fuel duty, although the effect on the pump price depends on how other costs and pricing decisions move. They can also pursue market oversight. Neither the cited figures nor the parliamentary record quantifies the price reduction, timing or distribution of benefits from any additional measure.
- Duty: changing the tax rate is a direct domestic policy lever. Its fiscal cost and the amount passed through to motorists are not quantified by the cited sources.
- Market oversight: in the House of Commons on 10 March 2026, Chancellor Rachel Reeves said the Government had asked the Competition and Markets Authority to look at price-gouging concerns. That is a record of the Government’s stated action, not a finding that price gouging caused September’s increase. House of Commons debate, 10 March 2026
- Global supply and oil markets: the Government can influence domestic policy, but it cannot dictate international crude-oil prices.
In that same Commons sitting, Reeves said: “The most important thing we can do to address the cost of living challenges people face is to de-escalate the conflict in the middle east, which is exactly what this Government are attempting to do.” This was her political statement on 10 March 2026, not an independent finding about the causes of September’s price increase.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Why can prices differ between petrol stations?
Forecourt prices can vary, so the price a driver pays depends partly on where they fill up. In March 2026, Reeves said the Government’s fuel price finder showed marked differences between forecourts and encouraged motorists to shop around. That is a statement made at the time, not a current measurement of local prices. Check the comparison service’s present availability and prices before relying on it.
Comparing nearby stations can help a driver choose a cheaper fill-up, but it does not resolve the underlying rise in wholesale or tax costs.
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