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PHEVs produce almost 5x greater global warming emissions than lab-reported figures indicate, according to a new report.

Widening Gap In Official and Real-World Emissions

Statistics reveals that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel vehicles, based on research carried out by a advocacy group. This differs significantly with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts studied information from onboard fuel consumption monitors of 800,000 vehicles registered in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” stated a lead researcher involved in the study. “This discrepancy is widening and creates a significant issue. As a result, PHEVs emit nearly as much as petrol vehicles.”

Primary Factors Driving the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric mode relative to total distance. They determined that only a quarter of travel was done in EV mode, while official estimates assumed 84%.

Additionally, when operating in electric mode, emission amounts were significantly higher than lab projections. This occurred because EV motors were not strong sufficient to function independently, leading to engines burning fossil fuels for nearly a third of the travel covered in EV mode.

Regulatory and Financial Consequences

According to calculations, the underestimation of PHEV emissions enabled several major automaker companies to escape over €5bn in penalties from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 more per year in operating costs than is estimated under laboratory tests.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are obviously far from the truth,” stated a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Debate and Automotive Pressure

Hybrid vehicles have lately been drawn back into policy discussions as carmakers have pressed the EU to weaken CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and resistance from member states with significant automotive industries.

Several high-level officials have suggested plug-in hybrids as a potential “compromise” option to include in the legislation.

An independent energy policy expert, who was not involved with the research, called the analysis a “very useful addition” after years in which parts of the car industry claimed there was insufficient data to properly evaluate real-world emissions.

“The results demonstrate, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel vehicles,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with utmost caution and considering that data.”