Used diesel prices are 6.9% over the past 12 months, according to the latest data from Solera cap hpi.
Analysis of vehicles at three years and 30,000 miles shows a clear change in direction for diesel during 2026.
While values were already falling, the decline has sharpened noticeably since March as rising pump prices have put greater pressure on demand.
The cumulative data show diesel increasingly separating from other fuel types during spring and summer, while hybrid and battery-electric vehicle values have moved in the opposite direction.
The gap reflects a growing focus on running costs among used car buyers as diesel prices have climbed to around 195p per litre, their highest level since July 2022. Diesel is now around 23p per litre more expensive than petrol, and filling an average-sized tank costs approximately £105.
The RAC has warned that prices have already topped £2 per litre on some forecourts as supply disruptions continue.
Chris Plumb, head of current valuations at Solera cap hpi, said: “The change in diesel values has become much more pronounced since March.
“Over the past 12 months, values at three years and 30,000 miles have fallen by 6.9%, and the trajectory shows how quickly buyer sentiment towards running costs can feed through into used car prices.
“Diesel at around 195p a litre is difficult for buyers to ignore, particularly when they are comparing it with hybrid and electric alternatives. Retailers are seeing that reflected in demand, with diesel stock needing to be particularly desirable or competitively priced.
“Hybrid is proving much more resilient. For many buyers it offers lower fuel costs without requiring a change in how they use or refuel their car, and that is supporting demand and values.”
Despite the pressure on diesel, Solera cap hpi said the wider used market remains relatively stable. Average values at three years and 60,000 miles fell just 0.3% in October, equivalent to a little over £90.
The figures suggest the fuel crisis is creating an increasingly divided used market, with buyers placing greater weight on day-to-day running costs and hybrids emerging as one of the main beneficiaries.
