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Plug-in hybrid electric vehicles emit almost 5x greater planet-heating emissions than lab-reported data indicate, as per a recent analysis.

Growing Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs emit just 19% lower CO₂ than conventional gas and diesel vehicles, based on research conducted by a non-profit organization. That differs significantly with lab estimates, which assumed a 75% decrease in emissions.

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

“Real-world CO2 output are rising, while official emissions are falling,” stated a lead researcher participating in the study. “That gap is growing and creates a serious issue. Consequently, PHEVs emit almost as much as petrol cars.”

Key Factors Driving the Discrepancy

Analysts linked the majority of the difference to overestimates of the “utility factor” – the ratio of miles driven in electric power relative to total mileage. They determined that just a quarter of travel was completed in electric mode, while official assumptions assumed 84%.

Additionally, when running in EV mode, pollution levels were significantly higher than lab projections. That happened because EV motors were insufficiently powerful enough to function independently, resulting to engines using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV emissions enabled several major carmaker groups to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 extra per year in running expenses than is estimated under laboratory conditions.

“The bold statements that manufacturers often promote about their PHEV cars are obviously far from the truth,” stated a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Political Debate and Automotive Pressure

Plug-in hybrid cars have recently been brought back into political discussions as automakers have lobbied the European Union to relax CO₂ standards. A proposed prohibition on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from EU countries with large automotive manufacturing.

Several high-level officials have proposed PHEVs as a potential “flexibility” option to introduce in the legislation.

One external energy economics specialist, who was not involved with the study, described the analysis a “highly valuable contribution” after a long period in which segments of the automotive industry claimed there was too little information to accurately assess actual emissions.

“The results show, without question, that the difference between lab and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel cars,” the expert stated. “Any policy changes regarding PHEVs should be implemented with extreme care and considering that evidence.”