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Plug-in hybrid cars emit almost 5x greater planet-heating pollution than lab-reported figures indicate, as per a recent report.

Growing Gap Between Official and Actual CO2 Output

Data reveals that PHEVs release only 19% lower CO₂ than traditional petrol and diesel vehicles, according to research conducted by a non-profit organization. That contrasts sharply with lab tests, which assumed a three-quarters reduction in emissions.

Researchers examined information from in-vehicle energy use meters of eight hundred thousand cars registered in Europe between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” stated a lead researcher participating in the study. “This gap is widening and creates a significant problem. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Key Factors Behind the Discrepancy

Analysts linked most of the gap to overestimates of the “electric driving share” – the percentage of miles driven in battery power compared to total distance. The team determined that just 27% of travel was completed in EV mode, while lab estimates assumed 84%.

Even, when operating in EV mode, pollution levels were significantly higher than lab projections. This occurred because EV motors were not strong sufficient to function alone, resulting to engines using gasoline for nearly one-third of the distance completed in EV mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four major carmaker groups to escape over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs could pay about €500 extra annually in operating expenses than is estimated under laboratory conditions.

“The bold claims that automakers often promote about their PHEV cars are clearly far from the mark,” commented a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Policy Debate and Industry Lobbying

Hybrid vehicles have recently been drawn back into policy discussions as automakers have pressed the European Union to relax CO₂ standards. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and resistance from member states with large car industries.

Several senior politicians have suggested plug-in hybrids as a potential “flexibility” option to include in the legislation.

An external energy policy expert, who was not involved with the research, described the analysis a “very useful contribution” after a long period in which parts of the automotive sector argued there was insufficient data to accurately evaluate actual emissions.

“These findings show, without question, that the gap in official and actual PHEV energy use and CO₂ output is much, much larger than for petrol or conventional cars,” they stated. “Any regulatory changes regarding PHEVs should be made with extreme care and considering that evidence.”