Plug-in hybrid electric vehicle owners are paying significantly more in fuel than manufacturers' official figures suggest, with eco campaigners warning of a cost gap exceeding £570 annually. According to Transport and Environment (T&E), real-world emissions from plug-in hybrids are just 14 per cent lower than conventional petrol and hybrid cars, far removed from official test claims of an 83 per cent reduction. This 69 percentage point discrepancy means drivers face a misleadingly rosy picture when deciding whether to buy one of these part-electric, part-petrol vehicles.
The gap between advertised and actual costs stems from how manufacturers calculate fuel economy in laboratory tests. Official ratings rely on a 'utility factor' that assumes plug-in hybrids run on battery power far more frequently than they actually do in the real world. Research from chargepoint manufacturer CTEK shows that one in six plug-in hybrid drivers never plug in their vehicles at all, whilst another 10 per cent charge only once a month. Just 39 per cent plug in daily, meaning many owners rely heavily on petrol engines rather than electric power, pushing fuel bills upward.
This is Money reported earlier this summer that average annual fuel and electricity costs for top-selling UK plug-in hybrids were estimated at around £540. However, research from the Energy and Climate Intelligence Unit shows plug-in hybrids consume 490 per cent more fuel than claimed, pushing the true annual bill to an average of £1,030. When factoring in servicing, tax, insurance and higher purchase prices, a new plug-in hybrid costs £4,150 more on average than a comparable electric vehicle, widening the financial burden for owners.
The European Union is attempting to address the problem by adjusting how official ratings are calculated. Using real-world fuel consumption data from on-board monitors installed on new vehicles since 2021, regulators are recalibrating tests. T&E notes that adjustments already planned for 2025-26 have prompted automakers to fit larger batteries and extend electric range. According to the European Environment Agency, these longer ranges offset three-quarters of the official carbon dioxide increases triggered by rule changes.
Plug-in hybrid registrations jumped 55.5 per cent year-on-year in September, with cheaper models from Chinese brands broadening their appeal. However, as fuel prices climb due to tensions between the US and Iran, the additional hidden costs to drivers are rising. Germany is currently lobbying to freeze further utility factor adjustments during Franco-German negotiations on broader automotive rules ahead of a key November update. Lucien Mathieu, cars director at T&E, said: 'A decade after Dieselgate, it is outrageous that Europe is once again debating whether to keep using misleading emissions to sell cars.'
For UK motorists, plug-in hybrids present a false economy compared to official marketing claims, with real costs running hundreds of pounds higher annually than manufacturers indicate. Drivers considering a plug-in hybrid should factor in substantially higher fuel costs than official figures suggest, making the overall ownership proposition more expensive than initially presented.