Why is diesel so expensive — and does the 60mph rule really save fuel?

Where prices are

On 30 September 2026 our fuel price tracker, which averages thousands of UK forecourts from the price files retailers publish under the official open-data scheme, had diesel at 200.6p a litre and petrol at 175.3p. On 8 September, the first day our tracker used its current mix of retailers’ price files, they were 187.7p and 166.2p: a rise of 12.9p a litre for diesel in just over three weeks — about £7.10 more to fill a 55-litre tank — and 9.1p for petrol. Our log goes back to 20 July, when diesel read 170.3p, but the retailers behind the average changed on 7 September, which on its own moved it by a penny or two, so we don’t compare across that date.

On the RAC’s long-running measure, the all-time record for petrol is 191.5p (3 July 2022), and diesel’s was 199.09p (25 June 2022) until 28 September, when the RAC’s UK average, published that morning, was 199.18p, up from 199.05p the day before. Diesel has kept rising since, to 199.72p on 30 September and 200.01p on 2 October, the first time the RAC’s UK average has passed £2 a litre (the RAC’s price table had no update on 1 October; the PA news agency, citing RAC figures, gave 199.79p for that day). The highest diesel figure the RAC’s table has published is 200.20p, on 5 October, and it has eased since: the RAC said on 9 October that its UK average had dipped back below £2 a litre, to 199.90p, still above the 2022 record of 199.09p. Petrol, at 174.79p that day, is nowhere near its record.

Other trackers, which sample differently, reported diesel records over the weekend of 26–27 September, which is why the headlines came in waves; the RAC’s figure is the one the 2022 record was set on. The different measures crossed £2 on different days. The RAC Foundation, a transport research charity that is separate from the RAC’s Fuel Watch table, analyses the government’s Fuel Finder scheme, the statutory feed in which forecourts report their prices. It said the UK average passed £2 a litre at 8 o’clock on the morning of 30 September. Our tracker’s second series averages the same feed by its own method: it read 200.0p on 30 September, as it had late on 29 September, with 33.7% of forecourts charging £2 or more. The RAC’s own table followed on 2 October, at 200.01p. The government’s weekly statistic, which gave 197.58p for 28 September, rose to 199.52p for 5 October (published on 6 October), above its previous high of 199.22p, set on 4 July 2022 (DESNZ). The tracker page updates daily, so check it rather than this paragraph.

Why diesel, in particular

The unusual thing this time is that crude oil is not the main culprit. The squeeze is in turning crude into diesel.

Two supply shocks have landed on top of each other. Russia, the world’s second-largest diesel exporter after the United States, banned diesel exports in July after attacks on its refineries, and has rolled the ban over month by month since — producers were let back in from September, traders were not. And the conflict in the Gulf since February has disrupted shipping through the Strait of Hormuz and taken refining capacity out of use; the International Energy Agency has reported a marked fall in global refinery output.

The result shows up in what traders call the crack spread — the gap between the price of crude and the price of the diesel made from it — which hit a record in August. A weaker pound adds a little, because fuel is priced in dollars. The AA has also pointed to retailer margins, which the competition regulator has criticised before.

How much of a litre is tax

Fuel duty is 52.95p a litre and is frozen until the end of 2026. VAT at 20% is then charged on the whole price, duty included. At around 196p a litre, duty and VAT together come to a little over 85p — roughly 43 to 44 per cent of what you pay.

Duty is scheduled to rise to 55.95p on 1 January 2027 and 57.95p on 1 March 2027. Those are the legal default rates in HMRC’s published schedule, but HMRC says “the government will confirm final rates at Budget 2026”, and the Budget is on Wednesday 28 October. With VAT, the two steps would add about 6p a litre. On 9 October the RAC asked the government to extend and increase the existing fuel duty cut, or to cut VAT on fuel as it has on domestic electricity (RAC, 9 October). Hauliers have asked for the planned rises to be scrapped and for an essential user rebate, according to Brit Brief (5 October). No decision has been announced.

Is there a shortage?

No. This is a price story in the UK, not a supply story. We could find no report of a UK forecourt running short of fuel, and no warning of one from the government, the RAC or the AA.

Reports of forecourts running dry are from France, where the situation is different. They do not describe Britain. The one thing that reliably creates a shortage here is everybody filling up on the same day, as in 2021 — when there was never a lack of fuel, only a lack of tanker drivers and a great many queues. Our guide to fuel shortages explains why joining a queue makes it worse. Headlines since 27 September about diesel rationing and a 50mph limit draw on a standing government emergency plan whose rationing measures have not been switched on, and whose published summary includes no speed limit; our rationing check sets out what it contains.

Does driving at 60mph really save fuel?

Yes, and it is one of the few fuel-saving claims with an official number behind it. A Department for Transport release from 2011 — the physics has not changed since — puts driving at 70mph at around a tenth more fuel than at 60mph, and 85mph at around a quarter more than 70mph. Air resistance rises steeply with speed, so the last 10mph is the expensive 10mph.

The headline running since 20 September, “Motorists urged to use 60mph rule as petrol and diesel prices rise today”, needs one clarification: the “60mph rule” is advice from motoring commentators, backed by a driver survey. It is not a change in the law and nobody is proposing to enforce it.

What it is worth: about 5 litres off a 55-litre tank, or roughly £10 at current diesel prices — if the whole tank goes on motorway miles. What it costs: on a 100-mile motorway run, 60mph instead of 70mph adds about 14 minutes. Whether that trade is worth it is yours to judge — but it is a real saving, not a myth.

What happens next (checked 9 October)

The RAC’s price table carries a forecast column. On its newest table, updated on 8 October, it marks both diesel and unleaded petrol “Should fall”. For diesel, every version from 23 September to the morning of 2 October read “Likely to rise”, versions from that afternoon read “No change forecast”, and it has read “Should fall” since 11:26 GMT on 6 October. The column gives a direction, not a size or a reason. The 8 October figures put diesel at 200.01p a litre on average, down from 200.20p on 5 October, the highest figure the table has published, and 215.43p at motorway services. On 9 October the RAC said the average had dipped back below £2, to 199.90p, and that diesel is still around 57p a litre dearer than before the US/Iran conflict (RAC, 9 October). Simon Williams, the RAC’s head of policy, said on 28 September: “Only a sustained lower oil price – over several weeks, not days – will lead to cheaper prices at the pumps.” Even a fall in crude, in other words, takes time to reach the forecourt.

What could bring it down. On 2 October the G7, the UK included, agreed to release 100 million barrels of emergency oil stocks through the International Energy Agency over four months, with “a frontloaded substantial diesel release” in the first 20 days (G7 leaders’ statement, GOV.UK). European diesel futures fell by 8% that day (The Irish Times). That is a wholesale price; how much of it reaches the pump, and how fast, is not yet known. On 7 October IEA member governments backed speeding up the stock releases and putting diesel first where possible. The IEA says about 325 million barrels have been released so far under its March plan, that releasing everything still pledged under it would bring about 100 million barrels to market, and that members hold about 1.1 billion barrels of public emergency stocks, including over 200 million of diesel (IEA statement, 7 October). The G7 statement presents its 100 million barrels as carrying out the March commitments, so our reading is that it is largely the unreleased part of the March plan rather than an extra release on top of it. The IEA says it stands ready to release more if needed, and its Governing Board was due to review the situation in the week of 12 October.

The outlets explaining why diesel may go higher mostly point to supply. Sky News’s business and economics reporter James Sillars, in an explainer headlined “Why record diesel prices have further to go” (28 September), pointed to refining rather than crude — “Limited diesel refining capability globally means volumes can’t just be increased elsewhere” — and to Britain’s own position: it makes enough petrol for its needs, but “we only produce about half the diesel we need”. He added that price pressures “will naturally become more baked in as we head towards peak winter demand”, and that the United States, “now responsible for around a third of UK imports”, is considering a ban on diesel exports.

The Times summed up its explainer, “Why Britain’s diesel prices could hit record highs” (26 September, before the record fell), in one line: “Global reserves are being used up as wars and export threats put the fuel supply under pressure.” Auto Express (28 September) pointed to the US Energy Information Administration, whose September outlook expects American diesel stocks to stay below their five-year low “through much of 2027”, though the same outlook expects crude oil to be cheaper next year. The EIA’s October outlook, published on 6 October from a forecast completed on 1 October, the day before the G7 deal, raised its fourth-quarter Brent forecast to $105 a barrel, $14 higher than a month earlier, pointing to “extreme tightness in diesel markets”, and expects Brent to fall to an average of $84 next year, up from the $74 it forecast a month earlier. The Energy and Climate Intelligence Unit, a think tank, said on 26 September that the possible US export ban could make things worse. There is no ban: on 2 October, after the G7 agreed the stock release, President Trump said one was “never really on the table” (CBS News).

On 30 September the Prime Minister, Andy Burnham, told BBC Breakfast that “every possible measure is being looked at” to cut the cost of driving, while asking how many the public finances could afford; the PA news agency reported that he left open the option of stopping January’s fuel duty rise. Any decision on duty is for the Budget on 28 October.

Nobody can promise where pump prices go from here, and we don’t forecast them: the RAC’s column is a direction, not a figure, and much rests on decisions in Washington and on the conflict in the Gulf. What helps is the same either way. Compare forecourts before you fill up — the RAC’s motorway-services average for diesel was about 15p a litre above its UK average on 8 October, about £8.50 on a 55-litre tank — using the nearest-forecourts lookup on our tracker. Since 8 October Google Maps has also shown near-real-time petrol and diesel prices from the same Fuel Finder scheme, as the government announced that day (DESNZ and HM Treasury, 8 October). It does not change prices; the government says comparing prices can save a household with a car around £40 a year. Buy as you normally would, and don’t queue or fill cans: that is what turns a price rise into a shortage. Our rationing check and US export ban explainer follow those two stories. If you are weighing up an electric car instead, the pence-per-mile numbers show where it comes out cheaper and where it doesn't.

What else works — and what to ignore

The measures with evidence behind them are dull and cheap. Take the roof box or bars off when you are not using them: the same release puts a roof box at around a quarter more fuel at motorway speeds. Don’t idle: the RAC reckons a stationary engine can burn up to half a gallon an hour. Accelerate gently and read the road ahead — the Energy Saving Trust recorded savings of about 15 per cent on the day of an eco-driving lesson, and 5 to 8 per cent a year later.

Correct tyre pressures, less weight in the boot and fewer short trips on a cold engine all help a little, though nobody puts a reliable single number on them. Fuel “additives” and gadgets that promise double-digit savings are not on any official list for a reason.

And don’t fill jerry cans “while it’s cheap”. Storing petrol at home is limited by law and is a genuine fire risk; the saving is a few pounds.