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PHEVs emit nearly 5x greater planet-heating pollution than official data indicate, as per a recent report.

Growing Gap Between Official and Real-World CO2 Output

Data reveals that PHEVs release only 19% less CO₂ than conventional petrol and diesel vehicles, according to research carried out by a non-profit organization. That contrasts significantly with laboratory tests, which assumed a 75% decrease in emissions.

Analysts examined information from in-vehicle fuel consumption monitors of 800,000 vehicles registered in the EU from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” stated a senior analyst participating in the study. “This discrepancy is widening and creates a significant issue. Consequently, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “electric driving share” – the percentage of miles driven in battery mode relative to total mileage. The team determined that just 27% of driving was completed in electric mode, while lab estimates assumed over four-fifths.

Additionally, when running in electric mode, pollution amounts were significantly higher than lab estimates. That occurred because EV motors were insufficiently powerful enough to operate independently, resulting to combustion motors using fossil fuels for almost a third of the distance completed in electric mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV emissions allowed several large automaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 extra per year in operating expenses than is assumed under laboratory tests.

“The bold claims that manufacturers often promote about their plug-in hybrid cars are clearly way off the truth,” stated a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Policy Debate and Industry Lobbying

Hybrid vehicles have lately been brought back into policy debates as automakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with large car manufacturing.

Several high-level politicians have proposed PHEVs as a potential “compromise” option to introduce in the regulation.

An independent energy policy specialist, who was not involved with the study, described the analysis a “very useful addition” after a long period in which segments of the car sector claimed there was too little information to properly evaluate real-world emissions.

“The results show, without question, that the gap between official and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional cars,” they stated. “All regulatory changes regarding PHEVs should be made with extreme caution and considering this data.”