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PHEVs produce nearly five times greater planet-heating emissions than official figures indicate, according to a recent report.

Growing Discrepancy Between Lab and Real-World CO2 Output

Statistics reveals that PHEVs release only 19% lower CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a non-profit group. That differs sharply with lab estimates, which assumed a three-quarters decrease in emissions.

Researchers studied data from onboard fuel consumption monitors of 800,000 cars sold in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” stated a lead researcher participating in the report. “That gap is widening and poses a significant problem. Consequently, PHEVs emit almost as much as gasoline vehicles.”

Primary Factors Driving the Emissions Gap

Researchers attributed most of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in electric mode relative to total mileage. They found that just 27% of driving was done in EV mode, while official assumptions assumed 84%.

Additionally, when operating in electric mode, emission amounts were well above official projections. This happened because electric motors were not strong sufficient to function alone, leading to combustion motors burning fossil fuels for nearly one-third of the travel completed in EV mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output allowed four major carmaker companies to avoid over €5bn in fines between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would pay approximately €500 extra per year in running expenses than would be estimated under lab conditions.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are clearly way off the mark,” stated a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Discussion and Industry Lobbying

Hybrid cars have recently been brought back into policy discussions as automakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from member states with significant car industries.

Several senior politicians have proposed PHEVs as a potential “compromise” solution to include in the regulation.

An independent energy economics specialist, who was unaffiliated with the research, described the analysis a “highly valuable addition” after a long period in which parts of the car sector claimed there was too little data to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel cars,” the expert stated. “Any policy changes regarding PHEVs should be implemented with extreme care and in the light of that data.”