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PHEVs produce almost 5x greater planet-heating emissions than lab-reported figures show, according to a new analysis.

Growing Gap In Lab and Real-World CO2 Output

Data shows that PHEVs emit just one-fifth lower CO₂ than traditional petrol and diesel cars, based on analysis conducted by a non-profit organization. This contrasts significantly with laboratory estimates, which assumed a three-quarters reduction in pollution.

Researchers examined information from onboard energy use meters of 800,000 vehicles registered in Europe between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official figures are falling,” said a lead researcher participating in the study. “This discrepancy is widening and creates a significant problem. Consequently, PHEVs emit almost as heavily as petrol cars.”

Primary Reasons Behind the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the percentage of miles driven in electric mode compared to total distance. They determined that just a quarter of travel was done in EV mode, whereas lab estimates assumed 84%.

Even, when operating in electric mode, pollution amounts were significantly higher than lab estimates. That happened because electric motors were insufficiently powerful enough to function alone, leading to engines using gasoline for nearly one-third of the travel covered in electric mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV emissions enabled several major carmaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 extra per year in operating costs than is estimated under lab tests.

“The strong statements that automakers like to make about their plug-in hybrid cars are clearly far from the mark,” commented a transport analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are only slightly better than standard petrol and diesel cars in terms of fuel use, CO₂ emissions, and running costs.”

Political Discussion and Industry Pressure

Hybrid cars have lately been brought back into political discussions as automakers have pressed the European Union to relax CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced heavy lobbying from the car industry and opposition from member states with large car manufacturing.

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

An independent energy policy specialist, who was not involved with the research, called the report a “very useful contribution” after a long period in which segments of the car sector claimed there was insufficient information to properly evaluate actual emissions.

“The results demonstrate, without question, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel cars,” the expert stated. “All regulatory changes regarding PHEVs should be made with utmost care and considering that evidence.”