The Energy and Climate Intelligence Unit (ECIU) published analysis on 9 May 2024 finding that the UK's ten best-selling plug-in hybrid electric vehicles (PHEVs) cost, on average, £500 more to fuel each year than their manufacturers claim1.
The report compared manufacturers' claimed fuel economy with real-world figures, using the gap identified in a European Commission report, and calculated costs for driving 8,000 miles a year. It also applied the European Commission's figure of 27.6% for the share of a typical PHEV's movement done using grid electricity1.
The findings set out three comparisons. Manufacturers' claims imply these PHEVs will save owners an average of £1,092 a year in fuel costs against equivalent petrol cars; ECIU puts the real saving at £593, just over half1. Against electric equivalents, the real-world fuelling costs of these PHEVs are £672 a year higher1. Switching from a petrol equivalent to the PHEV saves £593 a year in real-life fuelling costs, while switching to the electric equivalent saves £1,264, more than doubling the saving1.
"The UK's best-selling PHEVs cost, on average, £500 more to fuel each year than their manufacturers claim."
| Comparison | Annual real-life fuelling difference |
|---|---|
| PHEV versus manufacturer claim | £500 more than claimed |
| PHEV versus equivalent petrol car | £593 saving |
| PHEV versus equivalent electric car | £672 more expensive |
| Electric versus equivalent petrol car | £1,264 saving |
The report does not name the ten models, and no per-model figures have been reported1.
Why it matters for households
For a household weighing up a plug-in hybrid, the gap between the claimed and real fuel economy is money that does not appear on the showroom label. The ECIU figures suggest the running-cost case for a PHEV rests heavily on how much of its mileage is actually driven on grid electricity: the 27.6% assumption used in the analysis is far below what a driver charging regularly at home might expect, and a driver charging rarely would sit below it1.
That matters for energy independence because a PHEV's petrol engine ties the household to forecourt prices, while the electric share of its mileage can be met from a home charger and, where present, rooftop solar. The comparison in the report puts the fully electric equivalent £672 a year cheaper to fuel than the PHEV, and £1,264 a year cheaper than the equivalent petrol car1.
What happens next
No next steps, responses from manufacturers or government action are set out in the report1.