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PHEVs produce nearly 5x greater planet-heating pollution than official data show, according to a recent analysis.

Growing Discrepancy Between Official and Real-World Emissions

Data reveals that PHEVs emit only 19% less CO₂ than traditional gas and diesel cars, based on research conducted by a advocacy group. That differs sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers studied data from onboard energy use meters of eight hundred thousand cars registered in Europe between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are falling,” stated a lead analyst involved in the report. “This discrepancy is growing and creates a significant issue. Consequently, PHEVs pollute nearly as heavily as petrol cars.”

Key Reasons Behind the Discrepancy

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles driven in battery mode compared to overall mileage. They determined that only a quarter of driving was completed in electric mode, whereas official estimates assumed over four-fifths.

Additionally, when operating in EV mode, pollution amounts were well above official projections. This happened because electric motors were insufficiently powerful sufficient to function independently, leading to engines burning fossil fuels for nearly a third of the travel covered in EV mode.

Policy and Financial Consequences

Based on estimates, the underestimation of PHEV emissions enabled four major carmaker groups to avoid over €5bn in fines between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 more annually in running expenses than would be assumed under lab conditions.

“The strong statements that automakers like to make about their plug-in hybrid cars are obviously way off the truth,” commented a transport expert. “Buyers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are little improved than standard petrol and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Policy Discussion and Industry Pressure

Hybrid vehicles have recently been brought back into political discussions as carmakers have pressed the European Union to weaken CO₂ standards. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car sector and opposition from member states with significant car manufacturing.

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

An independent energy economics specialist, who was not involved with the study, described the report a “highly valuable contribution” after years in which parts of the car sector claimed there was insufficient information to properly evaluate actual CO2 output.

“The results show, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel cars,” they stated. “Any policy changes regarding PHEVs should be made with utmost caution and in the light of this evidence.”