Charged EVs | New study: plug-in hybrids use three times more fuel than automakers claim (even when drivers do plug them in)

Plug-in hybrids (PHEVs) are the epitome of a transitional technology. Their boosters say they enable drivers to complete many journeys on battery power, while offering more range for longer trips. Detractors say that they would, if owners actually plugged them in. Despite the best efforts of skeptical journalists, automakers have largely refused to release any data on how often their customers plug in their PHEVs.

A new study from the Fraunhofer Institute has found that PHEVs use much more fuel in real life than their manufacturers officially claim. The Institute carried out a large-scale analysis of about a million vehicles, using data transmitted wirelessly by PHEVs produced between 2021 and 2023 by several manufacturers.

As reported by The Guardian, the data enabled analysts to measure their real-world fuel consumption, as opposed to the figures included in the vehicles’ official EU-approved certifications. (The Fraunhofer study does not appear to have addressed the question of whether PHEV owners regularly plug in or not.)

The official fuel efficiency figures for PHEVs range from one to two liters of fuel per 100 km. (In Europe, fuel efficiency is measured in liters/100 km, not in MPG as in the States.) However, the Fraunhofer study found that, in real-world driving, the vehicles burned an average of six liters per 100 km, about three times more than automakers claim.

As every PHEV driver knows, the vehicle switches between electric and fossil power depending on which mode its little automotive brain deems to be appropriate at a particular time. Most models feature an “EV mode,” but even when driving in this mode, the gas engine will kick on from time to time. The Fraunhofer Institute’s researchers found that this is the main reason for the higher real-world fuel usage. Automakers tend to claim that their vehicles use little or no fuel when in EV mode. The study found that this is not the case.

Patrick Plötz of the Fraunhofer Institute told German broadcaster SWR that the combustion engines in PHEVs seem to turn on far more frequently than previously thought.

German-manufactured PHEVs were among those with the lowest fuel efficiency—the worst performers of all were from Porsche. The highest fuel efficiency levels were found at the budget end of the PHEV market, in vehicles from Kia, Toyota, Ford and Renault.

The Fraunhofer scientists have called for EU testing procedures to be revised to fit the real-world findings. In the EU, automakers face penalties for exceeding permitted limits on carbon emissions. Herr Plötz called on regulators to use the real-world emissions data. “Then one could say a manufacturer who does not comply with the [emissions] limits on the road may have to pay a penalty.”

Source: The Guardian