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Plug-in hybrid cars produce almost five times greater global warming pollution than official figures indicate, as per a recent analysis.

Widening Gap In Lab and Real-World Emissions

Data reveals that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on research carried out by a advocacy organization. That differs sharply with lab tests, which suggested a three-quarters reduction in emissions.

Analysts examined data from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” said a senior analyst participating in the study. “That discrepancy is widening and creates a serious problem. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Factors Driving the Emissions Gap

Analysts attributed most of the difference to overestimates of the “utility factor” – the percentage of kilometers driven in battery mode compared to total distance. They determined that only a quarter of driving was done in electric mode, whereas official estimates assumed over four-fifths.

Even, when running in electric mode, emission amounts were well above lab projections. This occurred because electric motors were not strong sufficient to function independently, leading to engines burning gasoline for nearly a third of the travel covered in EV mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV emissions allowed several major automaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend about €500 extra per year in running costs than would be estimated under lab tests.

“The strong claims that manufacturers often promote about their PHEV cars are obviously far from the truth,” commented a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are little better than standard petrol and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into policy discussions as automakers have lobbied the EU to relax CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the car sector and opposition from member states with large automotive manufacturing.

Several senior politicians have suggested PHEVs as a potential “flexibility” option to introduce in the regulation.

One independent energy policy expert, who was not involved with the research, called the analysis a “highly valuable contribution” after years in which segments of the automotive sector claimed there was too little data to accurately assess actual emissions.

“The results show, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ output is much, much larger than for petrol or diesel cars,” they stated. “Any policy adjustments regarding PHEVs should be implemented with extreme care and considering that data.”