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Plug-in hybrid electric vehicles emit almost 5x more global warming pollution than official figures indicate, according to a new report.

Widening Discrepancy Between Official and Actual CO2 Output

Statistics shows that PHEVs release just 19% less CO₂ than traditional petrol and diesel vehicles, according to research conducted by a advocacy organization. This differs significantly with lab tests, which assumed a three-quarters decrease in emissions.

Researchers examined data from in-vehicle fuel consumption meters of 800,000 vehicles sold in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are falling,” said a lead analyst involved in the report. “That gap is widening and creates a significant problem. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Key Factors Driving the Emissions Gap

Researchers linked most of the difference to overestimates of the “electric driving share” – the ratio of miles driven in electric power relative to total distance. They determined that just 27% of driving was completed in electric mode, while official assumptions assumed 84%.

Even, when running in electric mode, emission levels were well above official estimates. This happened because EV motors were not strong enough to function independently, resulting to combustion motors using fossil fuels for almost one-third of the distance completed in EV mode.

Policy and Economic Implications

According to calculations, the lowballing of PHEV CO2 output allowed several major automaker companies to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 extra annually in operating expenses than would be assumed under laboratory tests.

“The strong statements that automakers like to make about their PHEV vehicles are clearly far from the mark,” stated a transport expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Debate and Automotive Lobbying

Hybrid cars have lately been brought back into political discussions as carmakers have pressed the EU to relax CO₂ targets. A proposed prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and opposition from member states with significant automotive industries.

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

An independent energy policy specialist, who was not involved with the study, called the report a “highly valuable contribution” after years in which parts of the car sector claimed there was too little information to properly assess actual emissions.

“The results show, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or diesel vehicles,” the expert stated. “Any regulatory changes regarding PHEVs should be made with utmost care and in the light of this evidence.”