Diesel Nears Record Highs, Petrol Surges 17% — Inside the UK's Iran War Fuel Shock

Five weeks after US and Israeli strikes on Iran triggered the closure of the Strait of Hormuz, UK motorists are paying sharply more at the pump — and a fragile two-week ceasefire is doing little to bring relief.

Average diesel prices hit 191.1p per litre on 9 April 2026, just 8p short of the all-time record set in July 2022 [1][2]. Unleaded petrol reached 158.2p, up roughly 23p — or 17% — from the pre-conflict baseline of 135.5p in late February [1][12]. In the first three weeks of March alone, petrol rose 12p per litre and diesel jumped 25p [12].

These are not normal market fluctuations. They are the direct consequence of a military conflict that has effectively shut down the world's most critical oil transit chokepoint — and of a domestic fuel retail market that, according to the UK's competition regulator, was already failing consumers before the first missile was fired.

Source: BEIS/RAC

Data as of Apr 9, 2026CSV

The Strait of Hormuz and the Oil Price Shock

The price spike traces to 28 February 2026, when the US and Israel launched strikes on Iranian military targets. Iran's response included asserting control over the Strait of Hormuz, through which nearly 20% of global oil supply passes [3][5]. The strait has been effectively closed to commercial shipping since that date.

Brent crude averaged $103 per barrel in March — $32 higher than February [5]. Daily spot prices peaked near $128 on 2 April [5]. On 7 April, oil prices plunged more than 15% toward $90 per barrel after President Trump delayed threats against Iranian civilian infrastructure by two weeks [11]. But that drop reversed within 24 hours: on 9 April, Brent futures climbed back near $100 as it became clear that Iran still controlled access to the strait despite the ceasefire agreement [3].

The two-week ceasefire, under which Iran agreed to reopen the Hormuz passage while all attacks are halted, has not restored normal shipping. Trump described a 10-point Iranian proposal as a "workable basis for negotiations" [3], but commodity traders remain sceptical. As one CNBC analysis noted, the dated Brent spot price remained above $120 even after the ceasefire announcement — a sign that the market sees the underlying supply disruption as far from resolved [4].

The threshold at which rising crude prices historically begin to push UK pump prices higher within one to two weeks is approximately $75-80 per barrel [5][20]. Brent has been above that level continuously since late February.

Diesel: The Harder Hit

Diesel has been hit far harder than petrol, surging 48p — or 34% — since the conflict began, compared with petrol's 23p rise [1][12]. At 191.1p per litre, diesel is within striking distance of its July 2022 record of 199p [2].

Source: BEIS/RAC

Data as of Apr 9, 2026CSV

The disparity reflects diesel's greater sensitivity to crude price spikes and its different refining profile. Diesel refining margins — the "crack spread" — tend to widen more than petrol margins during supply disruptions because diesel is harder to substitute and more directly tied to commercial and industrial demand [12][16].

This matters because diesel is the fuel of the UK economy's physical infrastructure. Around 98% of goods in the UK are moved by road [17], and fuel accounts for 30-40% of haulage operating costs [16]. For small hauliers operating on profit margins as thin as 1-2%, the current price surge threatens viability [16]. Many are locked into fixed-price contracts that prevent them from passing costs through immediately, forcing them to absorb losses [16]. Some small logistics businesses have already exited the market [16].

The Road Haulage Association has described the situation as a major challenge, compounded by the government's confirmation that the temporary 5p fuel duty cut — first introduced in 2022 — will not be made permanent and is due to expire in September 2026 [8][16].

Who Pays the Tax — and How Much

At a pump price of 158p per litre for petrol, approximately 50-55% goes to the government in the form of fuel duty and VAT [7][14].

Source: PetrolPrices.co.uk/HMRC

Data as of Apr 9, 2026CSV

The breakdown: fuel duty is a flat 52.95p per litre (which includes a temporary 5p reduction from the standard 57.95p rate, in place since March 2022 and extended until 31 August 2026) [7][8]. VAT at 20% is then charged on the total price including the duty — meaning consumers pay tax on tax. On a litre at 158p, VAT amounts to about 26.4p, of which roughly 10.6p is VAT charged on the duty itself [7].

The wholesale product cost — reflecting global crude prices, refining margins, and distribution — accounts for roughly 68-69p at current prices [7]. The retailer margin takes the remaining 10p or so [6][7].

Fuel duty has been frozen in nominal terms since 2011, and the 5p temporary cut has been in place since 2022 [8][19]. In real terms, after adjusting for inflation, drivers are paying significantly less duty than they were a decade ago. The Office for Budget Responsibility has documented the fiscal cost of successive freezes [19]. From September 2026, duty will rise by 1p to 53.95p per litre — the first increase in 15 years — adding roughly 1.2p to pump prices after VAT [8].

So how much of the current price pain is tax policy versus oil markets? The answer is clear: virtually all of the recent increase — the 23p rise in petrol and 48p rise in diesel since February — is driven by wholesale cost increases flowing from the Iran conflict. The tax component has not changed. If anything, the frozen duty rate means drivers are paying less in tax (as a share of the pump price) than they would have under the pre-2011 escalator policy that linked duty to inflation.

Retailer Margins: Persistently High

Even before the Iran conflict, the Competition and Markets Authority had flagged serious concerns about fuel retail competition. In its first annual road fuel monitoring report, published in December 2025, the CMA found that fuel margins remained "above historic levels" and that this was "not explained by operating costs" [6][9].

The numbers are stark. On a trailing twelve-month basis through September 2025, the average fuel margin was 9.6p per litre for supermarkets and 11.1p for non-supermarket retailers [6]. Petrol retail spreads — the gap between wholesale and pump prices — averaged 13.9p per litre, more than double the 2015-2019 average of 6.5p [6]. For diesel, spreads averaged 14.6p versus a historic norm of 8.6p [6].

The CMA's conclusion was blunt: "overall competition in the UK's road fuel retail market remains weak" [6][9]. Operating profit margins for large fuel retailers were increasing, directly contradicting industry claims that higher costs explained the elevated margins [6].

Since March 2026, the CMA has accelerated its monitoring to determine whether retailers are exploiting the crisis to further widen margins [9]. Early indications suggest that the speed of pass-through from wholesale to retail has been asymmetric: prices at the pump rose rapidly as crude surged, but the brief 15% oil price drop on 7 April was not reflected at forecourts with comparable speed [1][11].

The steelman defence of current retailer behaviour runs as follows: margins have risen partly because lower-volume, higher-cost rural stations — which have always charged more — now make up a larger share of the market as supermarket fuel volumes have declined. Additionally, retailers argue they must price in the risk of further wholesale spikes, meaning current pump prices may reflect a prudent hedging premium rather than profiteering. The CMA's own data, however, shows that even supermarket margins — which should reflect the most competitive end of the market — have roughly doubled from pre-2020 levels [6].

Who Gets Hurt Most

The fuel price surge does not fall evenly. Lower-income households, rural communities, and workers without alternatives to car travel bear a disproportionate burden.

According to House of Commons Library research, households in rural areas have the highest fuel poverty rate at 15.9% [18]. A key driver is that 56.8% of rural households are off the gas grid, compared with just 9% in urban areas [18]. Among households not connected to mains gas, 20.1% are fuel poor, versus 12.3% for on-grid households [18]. The average fuel poverty gap — the additional spending needed to meet basic energy needs — for off-grid households is £804, more than three times the £222 gap for on-grid homes [18].

Transport fuel compounds this. Workers in rural areas with limited or no public transport — shift workers, care workers, agricultural labourers — have no realistic alternative to driving. A worker commuting 30 miles each way in a car averaging 40 miles per gallon is now spending roughly £18 per day on fuel at current diesel prices, up from £13 in February. Over a month, that is an additional £100 in costs on a take-home pay that may be £1,500-£2,000.

Small hauliers face a similar squeeze. With diesel at 191p, a 44-tonne HGV consuming roughly 8 miles per gallon costs approximately £1.08 per mile in fuel alone. For a small operator running 500 miles a day, that is £540 per day in diesel — up from £400 in February [16].

Regional price variation adds another layer. While the national average for petrol stands at 158p, prices in some areas diverge sharply. In Chelsea, London, petrol was reported at 238.7p per litre in March 2026 [2]. Northern Ireland, by contrast, offers the cheapest fuel in the UK at around 129-130p [2].

How the UK Compares Internationally

As of 6 April 2026, European petrol prices were broadly elevated by the same conflict-driven forces affecting the UK. Germany's Euro 95 petrol averaged €2.241 per litre, France's €2.032, and the EU average was €1.796 [10]. At the current exchange rate (approximately £1 = €1.17), the UK's 158p petrol price translates to roughly €1.85 — cheaper than both Germany and France, and close to the EU average [10].

For diesel, the picture reverses somewhat. Germany's diesel averaged €2.434 per litre and France's €2.234 [10]. The UK's 191p (approximately €2.23) is comparable to France and below Germany [10].

Several structural factors explain these differences. Germany's Energy Tax Act includes higher base excise rates than UK fuel duty, and both France and Germany apply higher VAT rates to fuel (20% and 19% respectively, but on higher base prices) [10]. The UK's relatively concentrated supermarket fuel retail sector — where Tesco, Asda, Sainsbury's, and Morrisons account for a large share of volume — has historically produced lower prices than the more fragmented European market, though the CMA's margin findings suggest this competitive advantage has eroded [6][10].

The US remains a stark outlier. American gasoline prices, even after the Iran conflict, remain far below European levels — roughly $3.80-4.20 per gallon (equivalent to approximately 75-85p per litre), reflecting lower taxes, greater domestic production, and refining capacity that is less dependent on Middle Eastern crude [10].

The Government's Toolkit

The UK government has several levers available, though most come with trade-offs.

Fuel duty: The most direct tool. The temporary 5p cut costs the Treasury approximately £2 billion per year [19]. Extending it beyond August 2026, or deepening it, would provide immediate relief but at a fiscal cost the government has signalled it is unwilling to bear [8]. The planned 1p rise in September 2026 — the first increase since 2011 — suggests the direction of travel is toward higher, not lower, duty [8].

The CMA and Fuel Finder: The CMA's 2023 road fuel market study made two central recommendations: a statutory Fuel Finder scheme providing real-time, station-by-station pricing to consumers, and an ongoing monitoring function to hold retailers accountable [9][13].

Both are now being implemented. Motor fuel traders were required to register with the Fuel Finder aggregator by 2 February 2026, and the scheme is expected to deliver consumer-facing price data through apps and satnavs during 2026 [13]. The Digital Markets, Competition and Consumers Act 2024 gave the CMA statutory information-gathering powers for its monitoring role [9][13].

The measurable effect so far is limited. The CMA's own data shows margins have not fallen since monitoring began, though the scheme's enforcement phase — as opposed to the current compliance-support period — does not begin until May 2026 [13]. Whether real-time price transparency will meaningfully constrain retailer behaviour remains an open question.

Emergency measures: In extremis, the government could invoke powers under the Energy Act to direct fuel distribution or impose price caps. These powers have never been used for retail fuel pricing and would face strong industry opposition. There is no indication the current government is considering them.

What Happens If the Ceasefire Collapses

The two-week US-Iran ceasefire is scheduled to expire in late April. If talks collapse and Brent crude returns to the $110-$120 range sustained in mid-2022, energy analysts project UK pump prices would follow accordingly.

At $120 Brent, petrol prices would be expected to reach 170-180p per litre and diesel could breach its 2022 record of 199p, reaching 200-210p [5][12][20]. At those levels, the average UK household — which drives approximately 7,400 miles per year — would face annual fuel costs of roughly £2,800-£3,000 for a petrol car, up from approximately £2,200 in early 2026 [2][12].

For haulage-dependent supply chains, the impact would be more severe. The Road Haulage Association's cost tables indicate that at diesel prices above 200p, average operating costs per mile for an articulated lorry exceed £1.13 [16]. Across the UK's estimated 500,000 HGVs, a sustained return to 2022-level diesel prices would add billions in annual transport costs — costs that would ultimately be passed to consumers through higher prices for food, building materials, and manufactured goods [17].

The base case among commodity analysts, however, is that sustained $120 Brent is unlikely even if the ceasefire fails, because high prices would trigger demand destruction and draw additional supply from US shale, Guyana, and Brazil [5]. The EIA's short-term outlook projects Brent averaging $95-105 through the second half of 2026 under a "continued disruption" scenario [5].

An Uncertain Road Ahead

The UK fuel price crisis of spring 2026 sits at the intersection of three forces: a geopolitical shock that has disrupted global oil supply, a domestic retail market with structurally weak competition, and a tax regime that — while frozen in nominal terms — still claims more than half of every pound spent at the pump.

For the millions of UK households and businesses that depend on road fuel, the coming weeks hinge on whether a two-week ceasefire can become something more durable. If it does, crude prices should fall and pump prices will follow — though, if past form is any guide, with the usual asymmetric delay. If it does not, UK motorists face the prospect of prices last seen during the worst of the 2022 energy crisis, with all the inflationary consequences that entails.

The CMA's margin data suggests that regardless of what happens in the Strait of Hormuz, UK drivers are paying more than they should be. The question is whether new transparency tools and regulatory scrutiny can close that gap — or whether, as in 2022, the crisis will pass and the structural problems will remain.