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PHEVs produce almost five times greater planet-heating pollution than official data indicate, as per a new report.

Widening Gap Between Official and Actual CO2 Output

Data reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, based on research carried out by a advocacy group. That differs significantly with laboratory tests, which suggested a three-quarters reduction in emissions.

Analysts studied information from onboard energy use monitors of 800,000 vehicles sold in the EU from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official figures are decreasing,” said a lead analyst participating in the study. “That gap is growing and creates a significant problem. As a result, PHEVs emit almost as much as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Analysts attributed the majority of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric mode relative to total distance. The team found that only a quarter of travel was completed in EV mode, while lab assumptions assumed 84%.

Even, when operating in EV mode, emission amounts were well above official projections. This occurred because electric motors were insufficiently powerful enough to function independently, leading to combustion motors using fossil fuels for almost a third of the travel covered in electric mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV CO2 output enabled four large automaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 more per year in running costs than would be estimated under laboratory tests.

“The bold claims that automakers like to make about their plug-in hybrid cars are obviously far from the mark,” commented a automotive analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the planet and saving costs. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of energy use, CO₂ production, and running costs.”

Policy Discussion and Automotive Lobbying

Hybrid cars have lately been brought back into policy debates as automakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the car industry and opposition from member states with significant automotive manufacturing.

Several high-level officials have proposed plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

One external energy economics specialist, who was unaffiliated with the research, described the report a “highly valuable contribution” after a long period in which segments of the car sector argued there was insufficient information to properly assess real-world emissions.

“The results demonstrate, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” the expert stated. “All policy changes concerning PHEVs should be made with utmost care and in the light of that evidence.”