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Plug-in hybrid electric vehicles produce nearly 5x greater planet-heating pollution than official data indicate, as per a recent report.

Widening Gap In Lab and Real-World Emissions

Data shows that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel vehicles, based on research carried out by a advocacy organization. That contrasts significantly with lab estimates, which assumed a three-quarters decrease in emissions.

Analysts examined information from in-vehicle fuel consumption meters of 800,000 vehicles sold in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” stated a senior analyst involved in the report. “That discrepancy is widening and poses a significant problem. As a result, PHEVs pollute almost as much as petrol cars.”

Primary Reasons Behind the Emissions Gap

Analysts linked most of the difference to overestimates of the “electric driving share” – the percentage of miles travelled in electric mode compared to total mileage. The team found that just 27% of travel was completed in EV mode, whereas lab assumptions assumed 84%.

Additionally, when running in EV mode, pollution amounts were significantly higher than lab estimates. That occurred because electric motors were not strong enough to operate alone, leading to combustion motors using fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several large carmaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 more per year in operating costs than would be estimated under laboratory conditions.

“The bold claims that automakers often promote about their PHEV cars are obviously far from the mark,” commented a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought again into political discussions as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and opposition from member states with large automotive industries.

Several high-level politicians have proposed plug-in hybrids as a potential “compromise” option to include in the regulation.

One independent energy policy expert, who was not involved with the research, called the analysis a “very useful contribution” after a long period in which parts of the automotive sector claimed there was insufficient information to accurately assess real-world emissions.

“These findings show, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ output is much, much greater than for petrol or conventional vehicles,” they stated. “Any policy adjustments concerning PHEVs should be made with utmost care and considering that evidence.”