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Plug-in hybrid cars emit nearly 5x greater planet-heating emissions than official data show, according to a recent report.

Widening Gap In Lab and Real-World CO2 Output

Statistics reveals that PHEVs release just 19% lower CO₂ than traditional petrol and diesel cars, according to research conducted by a non-profit group. That differs sharply with lab tests, which assumed a 75% decrease in emissions.

Researchers examined information from onboard energy use meters of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while official figures are falling,” said a lead researcher involved in the study. “This discrepancy is growing and creates a significant problem. Consequently, PHEVs pollute almost as heavily as petrol cars.”

Key Reasons Behind the Emissions Gap

Researchers attributed most of the difference to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric power compared to total mileage. The team determined that only a quarter of driving was done in EV mode, while official estimates assumed over four-fifths.

Additionally, when running in electric mode, emission amounts were significantly higher than official projections. That occurred because EV motors were insufficiently powerful enough to function independently, leading to combustion motors burning gasoline for nearly a third of the distance covered in electric mode.

Regulatory and Economic Consequences

Based on estimates, the lowballing of PHEV CO2 output allowed several major carmaker companies to escape more than €5bn in penalties from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ targets.

Additionally, owners of PHEVs could pay about €500 extra per year in running expenses than is assumed under lab conditions.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a automotive expert. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and running costs.”

Policy Discussion and Automotive Pressure

Hybrid cars have lately been drawn back into political discussions as carmakers have lobbied the EU to relax CO₂ targets. A planned prohibition on new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from member states with significant car industries.

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

One external energy policy expert, who was not involved with the study, called the report a “very useful contribution” after a long period in which segments of the automotive sector argued there was too little data to properly assess actual CO2 output.

“The results show, beyond any doubt, that the gap between official and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or diesel vehicles,” the expert stated. “Any regulatory adjustments regarding PHEVs should be made with extreme caution and considering that data.”