Plug-in Hybrid Drivers Face Higher Fuel Costs Than Advertised, Report Finds

Drivers of plug-in hybrid electric vehicles (PHEVs) may be spending over £570 annually on fuel costs beyond what manufacturers advertise, according to a report by the clean transport campaign group Transport & Environment (T&E).

The report criticizes official emissions figures for PHEVs, stating that the gap between advertised and real-world fuel efficiency is approximately six times wider than officially presented. This discrepancy is amplified as global fuel prices rise.

Discrepancies in Official Claims

T&E's analysis reveals that real-world emissions from PHEVs are only 14% lower than those of conventional petrol and hybrid cars. This contrasts sharply with official test claims of an 83% reduction. Even when operating in electric-only mode, the internal combustion engine reportedly powers the vehicle for about a third of the distance driven.

This aligns with previous findings from the Energy and Climate Intelligence Unit (ECIU), which warned that PHEV drivers could face fuel bills nearly double the expected amount. A primary reason cited is that petrol is more expensive per mile than electricity, and many drivers do not charge their vehicles frequently enough. Research from chargepoint manufacturer CTEK indicates that one in six PHEV drivers never plug in their vehicles, and another 10% charge only once a month, undermining the efficiency benefits.

Real-world Costs Exceed Estimates

Earlier reports estimated average annual fuel and electricity costs for top-selling UK PHEVs at around £540. However, factoring in the ECIU's finding that PHEVs consume 490% more fuel than claimed, the true annual bill could average approximately £1,030. When considering additional expenses such as servicing, tax, insurance, and higher purchase prices, a new PHEV can cost an average of £4,150 more than a comparable fully electric vehicle (EV).

Regulatory Efforts and Political Hurdles

The European Union is taking steps to address this emissions gap by revising the 'utility factor' used in official ratings. Regulators are recalibrating official tests using real-world fuel consumption data transmitted from on-board monitors in new vehicles. T&E notes that initial adjustments planned for 2025-26 have already prompted automakers to fit larger batteries and extend electric ranges, which helps offset increases in official CO2 figures.

However, political challenges persist. As a crucial November update to PHEV accounting rules approaches, Germany is reportedly lobbying to freeze further adjustments to the utility factor. Lucien Mathieu, cars director at T&E, stated, "A decade after Dieselgate, it is outrageous that Europe is once again debating whether to keep using misleading emissions to sell cars." He added that "Drivers deserve the truth, not another fix that shields carmaker profits while leaving motorists hundreds of pounds out of pocket."