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Plug-in hybrid cars produce almost 5x more global warming pollution than official data show, according to a recent analysis.

Widening Discrepancy In Official and Actual CO2 Output

Data reveals that PHEVs emit only 19% lower CO₂ than conventional gas and diesel cars, according to analysis conducted by a non-profit organization. That differs significantly with lab estimates, which assumed a three-quarters reduction in emissions.

Analysts examined data from onboard energy use meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, up from three and a half times in 2021.

“Real-world emissions are rising, while official figures are falling,” stated a lead researcher involved in the report. “That discrepancy is growing and poses a serious problem. As a result, PHEVs emit almost as much as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to total mileage. They found that only 27% of driving was done in EV mode, whereas official estimates suggested over four-fifths.

Additionally, when running in electric mode, emission levels were well above lab estimates. This occurred because electric motors were insufficiently powerful enough to operate alone, resulting to combustion motors using gasoline for nearly a third of the travel covered in EV mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV emissions allowed four major automaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay about €500 extra per year in running costs than would be assumed under lab tests.

“The bold statements that manufacturers like to make about their PHEV vehicles are clearly far from the truth,” commented a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are little improved than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have lately been brought back into policy debates as automakers have lobbied the EU to weaken CO₂ standards. A planned prohibition on new internal combustion cars in 2035 has faced intense lobbying from the car sector and opposition from member states with large car industries.

Some senior politicians have proposed PHEVs as a possible “flexibility” option to include in the legislation.

One independent energy policy specialist, who was not involved with the study, described the report a “highly valuable contribution” after a long period in which parts of the car sector argued there was too little data to accurately assess actual emissions.

“The results show, beyond any doubt, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or diesel cars,” the expert said. “Any regulatory changes concerning PHEVs should be implemented with utmost caution and in the light of that data.”