Source: BBC News, “Petrol prices rise by 5p over a week as Iran war sends oil higher”, published 9 September 2026, reporting RAC Fuel Watch data. Fuel duty figures are HMRC's own published policy paper, “Amended Fuel Duty rates: 2026 to 2027”, published 22 May 2026.
Our view, before the detail
Every headline this week is about the war pushing petrol up. That's real, and it's the smaller of the two things drivers should actually be tracking. The bigger one is sitting in an HMRC policy paper nobody's reporting on: fuel duty, frozen at a discount since March 2022, is legislated to start climbing back to its old rate from 1 January 2027 — a rise that has nothing to do with Iran, nothing to do with oil markets, and is already written into law unless a Chancellor chooses to stop it, which has happened every year since 2022 but is never guaranteed until it's announced.
Our view is that treating this week's rise as a one-off weather event is the mistake. It's a geopolitical shock on top of a policy change that's already scheduled. A household that only reacts to this week's number and doesn't look four months ahead is going to be surprised twice by the same underlying cost — once now, and once again in January, whether or not the war has cooled off by then.
What actually happened this week
The RAC says the average price of unleaded petrol rose 5p a litre in the space of a week — the biggest weekly increase since April — taking it to 167.17p. Diesel rose the same 5p, to 188.63p, though it remains a little below the 191.54p peak it reached in April. RAC senior policy officer Rod Dennis put it plainly: “Drivers are having to dig ever deeper into their pockets every time they fill up, and there's no sign of any relief yet.” He added that with the cost of a barrel of oil averaging $96 over the past week, “wholesale prices are surging and that's already feeding through to prices at the forecourt.”
The cause is the conflict between the US and Israel and Iran, which began at the end of February and severely disrupted crude oil supplies across the Middle East. Brent crude, the global benchmark, returned to $100 a barrel on Tuesday for the first time since July, as hostilities escalated again — US forces struck five Iranian tankers after Tehran targeted a US warship, and Yemen's Iran-backed Houthi movement attacked oil facilities in Saudi Arabia. $100 is some way below the $120 Brent hit back in April, but well above the roughly $70 it was trading at before the conflict started. Put simply: this is not the worst it's been, but it's the sharpest single-week move since April, and the last time petrol itself was this expensive at the pump was September 2022.
Illustrative family car, real published prices. The RAC says the 5p rise added £2.75 to the cost of filling a family-sized car — which, worked backwards, implies a tank of about 55 litres, in the range of a typical mid-size family hatchback.
- Full tank at this week's petrol price (167.17p): about £91.94.
- Same tank a week earlier, before the rise (162.17p): about £89.19 — the £2.75 difference RAC quoted.
- Diesel equivalent this week (188.63p): about £103.75 a tank.
If this week's price simply holds rather than reverting — no further rise, no fall — a household filling up weekly pays 52 × £2.75 = £143 a year more than they were paying seven days ago, purely from this one move.
The rise nobody's reporting: fuel duty in January
Here's the part that doesn't come from the war. Fuel duty on both petrol and diesel has been held at 52.95p a litre since March 2022 — a temporary 5p-a-litre cut from the pre-2022 rate of 57.95p, extended by the Chancellor every year since. HMRC's own policy paper, published 22 May 2026, confirms that cut now runs to 31 December 2026. Unless it's extended again at Budget 2026, the legislative default takes duty to 55.95p from 1 January 2027, then to the full 57.95p from 1 March 2027 — a rise of 5p a litre in total, entirely separate from anything the oil price does.
Illustrative, on HMRC's own published duty schedule and the 55-litre tank above.
- If duty rises 3p from 1 January 2027 as legislated: about £1.65 more per fill, assuming nothing else changes.
- If duty completes its return to 57.95p from 1 March 2027: about £2.75 more per fill than today — the same £2.75 the war added this week, but from tax policy rather than geopolitics.
- For a weekly filler, that's another potential £143 a year, stacking on top of whatever the oil price is doing by then.
Two separate 5p rises, two separate causes, the same size household impact. The duty rise is written into law today; whether it actually happens depends on a Budget decision that hasn't been made yet.
What it means for a real household this week
If you drive a family car and fill up roughly weekly, you're already about £2.75 worse off per tank than you were on 2 September, with the RAC saying there's no sign it stops there. That's not a crisis on its own, but it lands alongside everything else that's been rising this year, and it's the kind of cost that's easy to absorb once and dangerous to ignore as a pattern. The honest planning move isn't to panic about this week's 5p — it's to accept that fuel is now a genuinely less predictable line in the household budget than it was in the summer, and to check your numbers against what's actually coming in, not against what fuel used to cost.
What to do this week
- Check prices before you fill up, not after. The RAC's own advice is to use a fuel price comparison tool — its Fuel Watch page and app both show local averages — because the gap between the cheapest and priciest forecourt nearby is often bigger than a week's typical price move. Two minutes checking before a big fill-up beats guessing at the first garage you pass.
- Work out your real cost per mile for your actual car, this week. Take your fuel type's price above, your car's real-world mpg and your typical weekly mileage, and get an honest weekly figure rather than a feeling. If commuting has quietly become one of your biggest weekly costs, our cut your bills guide and budgeting guide help you see where it sits against everything else.
The RAC's other advice — driving gently, checking tyre pressures, clearing excess weight, combining short trips — genuinely saves fuel, typically in the region of 5–10%, which is worth doing because it's free. It won't offset a 5p-a-litre spike on its own, so treat it as a stack of small savings rather than the answer to this week's number.
What is still uncertain, and when we'll know
Two separate things are unresolved, on two different timelines. Nobody, including the RAC, is claiming to know when the Iran conflict eases or how much further it pushes oil prices — Dennis's own words are that there is “no sign of any relief yet.” That could change quickly or not for months; there's no dated event to point to here, only the ongoing news.
The fuel duty question does have a date. The government has said it will confirm final duty rates at Budget 2026, which hasn't yet been scheduled publicly. Until then, the legal default — a 3p rise from 1 January 2027 — stands. The freeze has been extended every year since 2022, so another extension is a reasonable bet, not a certainty, and it's worth watching the Budget announcement specifically rather than assuming the pattern continues automatically.
Where coaching ends and advice begins. Working out what fuel actually costs you, checking prices before you fill up, and deciding whether your commute still fits your budget — that's coaching, and it's all covered above. We're not going to pretend to know where oil prices or a Budget decision land months from now, and we wouldn't try to sell you a way to predict either. Buzz Money Coach is a trading style of Buzz Money Ltd, which does not give regulated financial advice and has no product to recommend here. If rising costs — fuel or anything else — are already meaning missed payments or reached-for credit, MoneyHelper, StepChange and National Debtline give free, independent help today, before a temporary squeeze becomes a debt problem.
The war will make headlines every time it moves the pump price. The duty rise won't make headlines at all until it lands — which is exactly why it's worth knowing about now, four months before it happens rather than the week it does.