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PHEVs produce nearly 5x more planet-heating pollution than lab-reported figures indicate, as per a recent analysis.

Growing Gap Between Lab and Actual CO2 Output

Data reveals that PHEVs release only 19% less CO₂ than conventional petrol and diesel cars, according to analysis conducted by a non-profit organization. That differs significantly with lab tests, which suggested a 75% reduction in pollution.

Analysts examined information from in-vehicle fuel consumption meters of eight hundred thousand cars registered in Europe between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are decreasing,” stated a senior researcher involved in the report. “This discrepancy is growing and poses a significant problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Researchers linked most of the gap to overestimates of the “electric driving share” – the ratio of miles driven in battery mode relative to overall distance. The team found that just a quarter of driving was completed in electric mode, whereas lab assumptions suggested 84%.

Even, when running in EV mode, emission levels were well above official projections. This occurred because EV motors were not strong sufficient to operate alone, resulting to combustion motors using gasoline for almost a third of the travel completed in EV mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV emissions allowed four large carmaker groups to avoid over €5bn in fines between 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ targets.

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

“The bold claims that manufacturers often promote about their plug-in hybrid cars are clearly way off the truth,” commented a transport analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel consumption, CO₂ production, and running expenses.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn back into political discussions as automakers have pressed the European Union to weaken CO₂ targets. A proposed prohibition on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with large automotive manufacturing.

Some high-level politicians have suggested PHEVs as a potential “flexibility” solution to introduce in the legislation.

One independent energy policy expert, who was unaffiliated with the research, described the analysis a “very useful contribution” after a long period in which segments of the car sector claimed there was insufficient data to accurately evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” they said. “All policy adjustments regarding PHEVs should be made with utmost caution and considering that evidence.”