UK pump prices did something unusual this spring, and the used car market is still working out what to do about it.
Between the first week of March and mid-April, according to the government’s weekly road fuel price series, the average UK diesel price went from 142.15p a litre to 192.14p. That is fifty pence a litre in six weeks — a 35% increase. Petrol moved too, from 132.14p to 158.17p, but nothing like as violently. At the April peak the diesel-over-petrol premium stood at just under 34p a litre, a spread that would have looked absurd to anyone who remembers when the two fuels traded within a few pence of each other.
Prices then eased through June and early July, bottomed out in the week of 6 July, and have since climbed again. As of the week commencing 3 August, petrol sits at 159.89p and diesel at 179.19p — petrol’s highest weekly average since late November 2022, diesel’s highest since mid-December 2022.
That is the actual event. Everything else is people reacting to it.
What the dealers say
Startline Motor Finance’s August Used Car Tracker asked motor retailers to rank eight possible explanations for the sudden strength in the used electric car market. Fuel prices came top, followed by increased choice from higher stock volumes and attractive pricing. Further down the list: EVs becoming more commonplace, more visible charging infrastructure, reduced fear of battery failure, and the effect of battery health checks. Startline says 85% of dealers expect the trend to run at least through the rest of 2026, and CEO Paul Burgess suggests the used EV market may be starting to mature.
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Worth knowing what you’re reading: the tracker is compiled by APD Global Research and this month’s panel was 300 consumers and 60 dealers. Sixty retailers ranking a pre-written list of causes is a sentiment reading, not a causal analysis. It tells you what the trade believes about its own forecourt, which is useful but not the same thing as evidence.
Fortunately there is evidence, and it landed the same day.
The transaction data backs it up — with a wrinkle
The SMMT’s second-quarter used car figures show battery electric transactions up 67.0% to 110,761 units, taking a record 5.5% share, up from 3.3% a year earlier. The overall used market grew just 0.7% to 2,009,318 units, so this is BEVs taking share, not a rising tide.
The month-by-month split is the interesting part. April was up 110.9%. May, 57.6%. June, 37.8%. Now go back and overlay the fuel data: April is exactly when diesel peaked, and June is when it was falling hardest. The growth curve tracks the pump, with a short lag. That is not the signature of a market maturing. That is the signature of a commodity input repricing and consumers responding — which is a perfectly respectable thing for a market to do, but it is a different phenomenon with a different risk profile.
The other number nobody is highlighting: used diesel transactions fell 7.2% to 620,045 in Q2, while petrol dipped only 1.2%. The fuel shock hit diesel roughly twice as hard as petrol, and diesel demand fell roughly six times as fast. Diesel is disproportionately exposed to middle-distillate supply disruption in a way petrol simply isn’t, and the used market has now priced that in. If you own a diesel and were thinking of moving it on, you have already taken the hit.
The arithmetic that actually drives this
Run the numbers rather than the vibes. At 159.89p a litre, a car returning a real-world 45mpg costs about 16.2p a mile in fuel. A 55mpg diesel at 179.19p costs about 14.8p.
An EV charged at home on the July-to-September Ofgem cap rate of 26.11p per kWh, managing a realistic 3.5 miles per kWh, costs roughly 7.5p a mile. Less than half. On an overnight EV tariff it is a fraction of that.
Two policy wrinkles make this gap wider still, and both are worth understanding before you sign anything.
First, from 1 October the government is removing VAT from domestic electricity bills in England, Scotland and Wales, cutting the rate from 5% to zero for the remainder of the financial year. Home charging gets cheaper again.
Second, it doesn’t help you if you park on the street. HMRC’s position, restated in Revenue and Customs Brief 4 (2026), is that public charge points aren’t domestic premises, so the electricity you buy there stays standard-rated at 20%. From October the same electron will be taxed at 0% on a driveway and 20% at a kerbside post. That is a 20-point wedge running straight through the middle of the used EV buyer pool.
Meanwhile the pump price you’re escaping is itself mostly tax. At 159.89p, with duty still frozen at 52.95p and VAT at 20%, roughly 79.6p of every litre — very nearly half — is going to the Treasury. Fuel shocks are always partly geopolitics and partly a fixed levy amplifying the volatility.
The infrastructure line deserves a squint
Dealers ranked “visibly better charging infrastructure” fifth. The Department for Transport counted 119,080 public EV chargers in the UK as of 1 April 2026, of which 27,372 were rated 50kW or above. But half the national network sits in the 3kW-to-8kW band — useful if you’re parked for eight hours, useless if you’re not.
And the regional picture is stranger than the headline. London has 340 chargers per 100,000 people, comfortably the highest in the country, yet the second-lowest per-capita provision of rapid-or-above units. The capital’s network is overwhelmingly slow on-street posts. A Londoner without a driveway is technically well served and practically inconvenienced, and paying 20% VAT for the privilege.
What buyers should actually check
The two factors dealers ranked last — reduced fear of battery failure, and battery health checks — are the ones doing the real structural work here, and they’re the ones that survive a fuel price retreat.
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State-of-health testing has turned battery degradation from a rumour into a measurable number on a certificate, which is what allowed trade valuations to firm up. But the warranty position is where buyers get caught out. Volkswagen’s UK warranty terms are typical of the industry: its BEV battery degradation cover runs eight years or 100,000 miles to a 70% capacity floor and passes to subsequent owners. Its PHEV degradation warranty runs five years or 100,000 miles and applies to the first owner only — explicitly non-transferable.
That asymmetry is almost certainly part of why used PHEV transactions fell 6.8% in Q2 while BEVs surged. A three-year-old used BEV comes with five years of transferable battery protection. A three-year-old used PHEV comes with none. If you’re shopping plug-in hybrids second-hand, that is the single most expensive line in the small print.
The skeptical bit
Buying an EV because petrol went up is buying into the top of a demand spike. Used EV values are firming precisely because a war moved the price of a barrel, and wars end. When diesel retreated 27p between mid-April and early July, used BEV growth roughly halved within two months. The elasticity runs both ways.
None of which makes a used EV a bad car. At 7.5p a mile against 16p, with a transferable battery warranty and a health certificate, the case stands up on its own without help from the Strait of Hormuz. Just don’t pay a fuel-panic premium for a car you’d have wanted anyway — and if you can’t charge at home, do the sums at 20% VAT before you sign, not after.