Every time Brent crude drops sharply, the same question lands in our inbox: why is the pump not following? Drivers notice the rocket — prices at Shell, BP, Esso and the supermarkets tend to jump within days of a crude spike — but the feather on the way down can take weeks. The pattern is real, it has been documented by the RAC, the AA and the Competition and Markets Authority, and it has a measurable cost. This piece walks through the numbers, the mechanics and what a driver can actually do about it.
What the pump is actually made of
A litre of UK petrol is not mostly oil. On a typical day when petrol sits near 135p/L, roughly 53p is fuel duty, around 22p is VAT, and the wholesale product cost — which reflects crude plus refining — is usually 45–55p. The retailer and delivery margin makes up the balance, historically 5–8p but pushed higher in recent years according to the CMA's 2023 road fuel market study.
That structure matters. Because duty and VAT are largely fixed in cash terms (duty) or proportional (VAT at 20%), a 10% fall in Brent does not translate to a 10% fall at the pump. If crude drops by around 8p on the wholesale side, the maximum pump saving before margins is closer to 6% of the total price, not 10%.
The DESNZ weekly road fuel price series makes this visible: pump prices track wholesale, but with a lag and a dampened amplitude. That is the honest baseline before we even get to retailer behaviour.
The rocket-and-feather effect, quantified
Economists have studied asymmetric price transmission in fuel markets for decades. In the UK, the RAC's monthly Fuel Watch has repeatedly shown that when wholesale costs rise by, say, 5p/L, retailers typically pass it through within one to two weeks. When wholesale costs fall by the same 5p/L, the pass-through often takes three to six weeks — and is sometimes incomplete.
The CMA's 2023 findings put a number on the drag: supermarket fuel margins roughly doubled between 2019 and 2022, adding around 6p/L to what drivers paid on average. That is not a conspiracy, but it is a market where competitive pressure on the way down is weaker than the cost pressure on the way up.
The chart below sketches the pattern using indicative figures consistent with DESNZ and RAC reporting for a typical crude cycle. The exact weeks vary, but the shape — fast up, slow down — is the persistent feature.
Why the feather is so slow
Several mechanics compound. Retailers hold stock bought at the older, higher wholesale price and are reluctant to sell it at a loss, so they wait. Motorway sites and rural single-station villages face little local competition and can hold prices for weeks. Supermarkets, historically the price-setters, have been slower to trigger price wars since 2022.
There is also a behavioural asymmetry. Drivers notice a 3p rise immediately and complain; a 3p fall is quietly pocketed. That reduces the reputational cost of delaying a cut. The AA has made this point repeatedly in its monthly Fuel Price Report.
None of this is illegal. It is simply what happens in a market with sticky demand, concentrated retail and limited price transparency at the forecourt level — which is exactly why the CMA has pushed for a live pump-price open data scheme.
What a driver can actually do
You cannot fix the market, but you can stop overpaying during the feather phase. The gap between the cheapest and most expensive station within a 5-mile radius is often 10–15p/L, according to RAC survey data — larger than the entire crude move you are waiting on.
Practical steps that materially move the needle:
The takeaway
The rocket-and-feather effect is not folklore; it is a documented pattern in UK fuel retailing, driven by tax structure, stock lags, thin local competition and widened retailer margins. Crude falls will reach the pump, but slowly and incompletely. The bigger, faster win for most drivers is not timing the market but avoiding the 10–15p/L premium at the wrong forecourt. Use a price app, watch the RAC and DESNZ weekly numbers, and treat any single station's price as a choice, not a fact.
