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PHEVs produce nearly five times greater global warming pollution than official figures show, according to a new report.

Widening Gap Between Official and Real-World CO2 Output

Data shows that PHEVs release just one-fifth lower CO₂ than traditional petrol and diesel cars, based on analysis carried out by a advocacy group. That contrasts sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers examined data from onboard energy use monitors of 800,000 cars sold in the EU from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official figures are falling,” stated a senior analyst involved in the report. “This gap is growing and poses a significant problem. Consequently, PHEVs emit nearly as much as petrol cars.”

Key Factors Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the ratio of miles driven in electric mode relative to total mileage. The team found that just a quarter of travel was completed in EV mode, while lab estimates suggested over four-fifths.

Additionally, when operating in electric mode, pollution levels were well above lab estimates. That occurred because EV motors were insufficiently powerful enough to operate independently, leading to combustion motors burning gasoline for nearly a third of the travel completed in EV mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV emissions enabled several large carmaker groups to avoid more than €5bn in fines between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay about €500 more per year in operating costs than is estimated under lab conditions.

“The bold statements that manufacturers often promote about their PHEV vehicles are obviously far from the truth,” commented a transport analyst. “Consumers are being misled into believing that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running expenses.”

Political Debate and Automotive Lobbying

Hybrid cars have lately been brought back into political debates as automakers have pressed the EU to relax CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced intense pressure from the car industry and opposition from EU countries with large automotive manufacturing.

Several high-level politicians have proposed PHEVs as a possible “flexibility” solution to include in the legislation.

One external energy economics specialist, who was not involved with the study, called the report a “highly valuable contribution” after years in which segments of the car industry claimed there was insufficient data to properly evaluate actual CO2 output.

“The results show, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel cars,” they said. “All regulatory adjustments regarding PHEVs should be made with utmost care and considering this data.”