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PHEVs produce nearly five times greater planet-heating pollution than lab-reported figures indicate, according to a new analysis.

Growing Gap Between Lab and Real-World CO2 Output

Data shows that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel cars, based on analysis carried out by a advocacy group. That contrasts sharply with laboratory estimates, which assumed a 75% reduction in emissions.

Researchers examined data from onboard energy use meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” said a senior analyst involved in the study. “That gap is widening and poses a serious issue. Consequently, PHEVs pollute almost as much as gasoline cars.”

Primary Factors Behind the Discrepancy

Analysts attributed the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles driven in battery power relative to total distance. They determined that just 27% of travel was completed in EV mode, while lab assumptions suggested 84%.

Additionally, when operating in EV mode, emission amounts were well above official projections. That occurred because electric motors were not strong sufficient to function independently, resulting to engines burning gasoline for nearly one-third of the distance covered in EV mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV CO2 output enabled four large carmaker companies to escape over €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs would spend approximately €500 extra annually in running costs than is assumed under laboratory tests.

“The bold claims that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the truth,” stated a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have lately been drawn back into political debates as carmakers have lobbied the EU to relax CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from member states with significant automotive manufacturing.

Several senior politicians have suggested PHEVs as a potential “compromise” option to include in the legislation.

One independent energy policy expert, who was not involved with the study, called the analysis a “highly valuable contribution” after years in which segments of the automotive sector argued there was too little data to accurately evaluate real-world emissions.

“The results show, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” they stated. “Any regulatory adjustments regarding PHEVs should be implemented with extreme care and considering that evidence.”