Plug-in hybrids use three times more fuel than manufacturers claim, analysis finds

"Plug-in hybrid electric cars (PHEVs) use much more fuel on the road than officially stated by their manufacturers, a large-scale analysis of around a million vehicles of this type has shown. The Fraunhofer Institute carried out what is thought to be the most comprehensive study of its kind to date, using the data transmitted wirelessly by the PHEVs whilst they were on the road, from a variety of manufacturers. The cars involved were all produced between 2021 and 2023. The data transmitted enabled analysts to determine their precise and real-world fuel consumption, as opposed to those stated in the vehicles' official European Union approved certification."

"PHEVs, cars which combine a petrol or diesel engine with a battery-powered electric motor that is charged from an external energy point, give drivers the flexibility to be able to switch between the ecologically safer power source, and the more conventional, but environmentally more damaging one as and when conditions allow. Manufacturers typically market the vehicles as energy efficient. On paper at least, the vehicles are said to use much less fuel, between one and two litres per 100km, than conventional cars. However environmental groups have long since voiced their scepticism over the claims."

"According to the study, the vehicles require on average six litres per 100km or around 300% more fuel to run than previously cited. The scientists of the Fraunhofer Institute found that the main reason for the higher-than-stated fuel usage was due precisely to the fact that the PHEVs use two different modes, the electric engine and the combustion engine, switching between both. Until now it has been claimed by manufacturers that the vehicles used only a little or almost no fuel when in the electric mode. The studies showed that this was not in fact the case."

Analysis by the Fraunhofer Institute of wirelessly transmitted on-road data from about one million PHEVs produced between 2021 and 2023 determined real-world average fuel consumption is about 6 L/100km, roughly 300% higher than EU certification figures. Manufacturers report on-paper consumption of 1–2 L/100km and market PHEVs as energy efficient. PHEVs combine a combustion engine with an externally charged battery-powered electric motor and switch between modes. Higher real-world fuel use results from mode switching and combustion-engine operation even during supposed electric mode, contradicting near-zero fuel claims.

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