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Plug-in hybrid electric vehicles produce almost 5x more planet-heating emissions than official figures indicate, as per a recent analysis.

Widening Discrepancy In Lab and Actual Emissions

Data shows that PHEVs release just 19% less CO₂ than conventional petrol and diesel cars, according to analysis carried out by a advocacy group. That contrasts significantly with lab estimates, which assumed a three-quarters reduction in pollution.

Researchers studied data from in-vehicle energy use meters of 800,000 vehicles sold in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while official emissions are decreasing,” stated a senior researcher participating in the study. “This discrepancy is widening and creates a serious issue. Consequently, PHEVs emit nearly as heavily as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in battery power compared to total distance. They determined that just 27% of driving was done in electric mode, while official assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution amounts were significantly higher than official projections. That occurred because EV motors were not strong enough to function independently, leading to engines using gasoline for nearly one-third of the distance completed in EV mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled several large automaker groups to escape over €5bn in fines between 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 more annually in running costs than would be assumed under lab conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the mark,” commented a transport expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little better than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Policy Debate and Automotive Pressure

Hybrid vehicles have recently been brought back into political debates as automakers have pressed the EU to relax CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with large car manufacturing.

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

An independent energy policy expert, who was not involved with the study, described the analysis a “very useful addition” after years in which parts of the car industry argued there was too little information to accurately assess actual emissions.

“The results demonstrate, beyond any doubt, that the gap between official and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel cars,” the expert said. “All policy changes regarding PHEVs should be made with utmost care and in the light of that evidence.”