RAC Data Shows Diesel Near War Highs as Drivers Pay £3.85 More a Tank

Diesel now averages 190.08p a litre and petrol 168.46p, both up 7p a litre from the start of September, according to RAC Fuel Watch data.

Filling a typical 55 litre family car costs £3.85 more than it did on 1 September, with the oil price trading close to $108 a barrel.

Supermarkets are selling fuel for around 4p a litre less than the UK average, and some independent forecourts are pricing petrol below 158p.

UK drivers are watching the pumps climb again. RAC Fuel Watch data released across three separate statements this month, on 4, 9 and 11 September, shows diesel and petrol both rising fast enough that Rod Dennis, the RAC’s senior policy officer, said diesel is on course to hit a new high for the US/Iran conflict “within days”. The average price of unleaded now stands at 168.46p a litre and diesel at 190.08p, with both fuels up 7p a litre in eleven days. That has added £3.85 to the cost of filling a typical family car compared with the start of the month.

The cause sits thousands of miles away. A barrel of oil jumped $6 overnight in the run-up to 11 September to trade close to $108, its highest point for months, as tensions built around Yemen and the wider US/Iran standoff. Wholesale prices for diesel in particular have moved fastest, widening the usual gap between the two fuels at UK forecourts.

Fuel duty, the flat tax levied on every litre sold, plays no part in this particular rise. Standard petrol and diesel duty has stayed at 52.95p a litre through to the end of 2026, after a planned staged increase, 1p from 1 September, 2p from 1 December and a further 2p from 1 March 2027, was scrapped earlier this year to shield drivers from the same conflict-driven costs now pushing prices up regardless. That makes the current increase unusual: every extra penny at the pump this month is down to the oil market alone, with no tax change adding to it.

The Gap Between What You’re Paying and What You Paid in June

The scale of the swing becomes clearer set against the rest of 2026. RAC data recorded diesel falling by a record 17p a litre in June, alongside an 8p drop in petrol, as a US/Iran deal briefly took pressure off wholesale prices. That relief did not last. Petrol had already hit a three-and-a-half year high in July as the conflict resumed, and by early September the RAC was warning, again, that pump prices were “set to rise once again”.

Three RAC statements track the climb in close detail. On 4 September, unleaded stood at 163.36p and diesel at 184.99p, with the oil price above $94 a barrel for the first time from before the summer. By 9 September, both fuels had risen a further 5p in a single week, taking unleaded to 167.17p and diesel to 188.63p, and adding £2.75 to a family car’s fill-up over that short stretch alone. Two days later, the 11 September figures showed unleaded at 168.46p and diesel at 190.08p, with the RAC directly linking the rise to a barrel price nearing $108.

For a household running a diesel car and filling up weekly, that run of increases is not abstract. Based on the RAC’s own comparison, the same car cost £4 more to fill on 11 September than it did at the start of the month, and the gap to the highs of the Ukraine war years, when diesel peaked at 199p a litre, is narrowing every week the conflict continues.

Who Feels This Hardest

Diesel drivers are absorbing the bigger share of the increase. The RAC’s own figures show diesel rising faster than petrol in every one of the three statements this month, a pattern it puts down to wholesale diesel markets reacting more sharply to Middle East supply concerns than petrol markets do. Anyone covering long motorway mileage, including tradespeople, delivery drivers and rural commuters with no realistic public transport option, is exposed to the full 7p-a-litre rise with no way to reduce their mileage in the short term.

Households on the tightest budgets are also least able to absorb a rise of this size. RAC research the organisation has published previously found that eight in ten people rely on their car, so a run of weekly increases lands directly on food and childcare budgets rather than discretionary spending that can be cut back.

The wider fleet sector is watching the same figures with real concern. Haulage, coach and van operators typically run almost entirely on diesel and cannot pass every cost rise straight on to customers on short notice, so a 7p-a-litre jump in a single fortnight puts direct pressure on the margins of businesses that already operate on thin ones. Industry bodies have used this month’s price rises to renew calls on the Government for a clear fuel contingency plan, arguing that repeated conflict-driven spikes are becoming a recurring cost that policy has not caught up with, rather than a one-off shock.

Can You Avoid Paying the Extra £3.85?

There is no way to avoid the wholesale price rise, but there are ways to stop paying more than you have to on top of it.

Shop at supermarkets first. The RAC’s 11 September data put supermarket fuel at around 164p for petrol and 186p for diesel, roughly 4p a litre cheaper than the UK average on both fuels. Over a 55 litre tank, that is a saving of more than £2 simply by choosing where you fill up.

Check independent forecourts too. The same RAC statement noted some independent stations pricing petrol below 158p a litre, a gap of more than 10p against the national average. Independents do not always undercut the majors, so it is worth checking rather than assuming.

Use a free price comparison app before you drive to a station. RAC’s own myRAC app tracks live prices nearby, and the Government’s Fuel Finder scheme, launched to give drivers “the information they need to see where fuel is cheapest locally,” now feeds data to apps including Confused.com, PetrolPrices and MotorMouth as well. Checking one of these before a long journey, rather than filling up at the first station you pass, is the single most direct way to reduce what a tank actually costs.

Fill up before a long trip rather than mid-journey. Motorway services routinely charge well above the national average, so topping up close to home or at a supermarket before setting off avoids paying a premium on top of an already-rising price.

Time larger fill-ups around price statements where you can. RAC Fuel Watch data updates through the month, and prices tend to move in the direction wholesale oil costs are heading. When RAC statements point to a rise “within days,” as they did on 11 September, filling up before that rise lands, rather than after, can make a real difference over a month of driving.

None of these steps will offset a global oil price rise entirely, but combined they can claw back several pounds a tank while the US/Iran conflict continues to drive prices at the pump.

What happens next depends on a conflict most drivers have no control over. RAC statements this month have consistently pointed to the rise as a direct read-through from the oil market rather than anything happening in the UK fuel supply chain, which means the same volatility that pushed diesel down by a record 17p in June could just as easily reverse the current rise if tensions ease. Until then, RAC Fuel Watch data suggests prices are more likely to keep climbing than fall back, making this a month to check prices before filling up rather than assume the pump you know best is still the cheapest one.

Sources

RAC Media Centre, “RAC warns pump prices set to rise once again,” 4 September 2026.

RAC Media Centre, “Fuel prices spike spelling more misery for drivers,” 9 September 2026.

RAC Media Centre, “Diesel prices expected to hit US/Iran war high within days, RAC warns,” 11 September 2026.

RAC Fuel Watch, ongoing UK retail fuel price data, rac.co.uk/drive/advice/fuel-watch.