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PHEVs produce almost five times greater planet-heating emissions than lab-reported data show, according to a recent analysis.

Growing Discrepancy Between Lab and Real-World Emissions

Data shows that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a non-profit group. That differs significantly with laboratory estimates, which suggested a 75% reduction in emissions.

Researchers examined data from onboard fuel consumption monitors of eight hundred thousand vehicles registered in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported figures are falling,” stated a lead analyst participating in the study. “This gap is growing and creates a serious issue. As a result, PHEVs emit almost as much as gasoline cars.”

Primary Reasons Driving the Discrepancy

Analysts attributed most of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in battery mode relative to total distance. The team found that only a quarter of driving was done in EV mode, while official assumptions suggested 84%.

Additionally, when operating in EV mode, emission levels were well above official estimates. This occurred because electric motors were insufficiently powerful sufficient to operate independently, resulting to engines using gasoline for nearly one-third of the distance completed in electric mode.

Policy and Economic Implications

According to calculations, the lowballing of PHEV CO2 output allowed four major automaker groups to escape over €5bn in fines between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Furthermore, drivers of PHEVs would pay approximately €500 extra per year in operating costs than is assumed under laboratory conditions.

“The bold claims that automakers like to make about their PHEV vehicles are clearly far from the truth,” commented a automotive analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Pressure

Hybrid vehicles have lately been brought back into policy discussions as carmakers have pressed the EU to relax CO₂ standards. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense lobbying from the car sector and opposition from member states with large automotive manufacturing.

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

An external energy economics specialist, who was not involved with the research, called the analysis a “highly valuable contribution” after years in which parts of the car sector argued there was too little data to properly evaluate actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” they said. “All policy adjustments regarding PHEVs should be implemented with extreme care and considering this evidence.”