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PHEVs release nearly five times greater planet-heating pollution than official figures show, according to a recent analysis.

Growing Discrepancy Between Official and Actual CO2 Output

Data reveals that PHEVs release only 19% less CO₂ than traditional gas and diesel cars, based on research carried out by a non-profit group. This differs significantly with laboratory tests, which suggested a 75% decrease in emissions.

Analysts examined data from in-vehicle fuel consumption meters of eight hundred thousand cars 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 official estimates, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are decreasing,” stated a senior researcher participating in the report. “That gap is growing and poses a significant problem. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Researchers linked most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to overall mileage. The team found that just a quarter of travel was completed in EV mode, while lab assumptions suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were well above lab estimates. That happened because EV motors were insufficiently powerful sufficient to operate independently, leading to combustion motors using gasoline for almost a third of the travel completed in electric mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV CO2 output allowed several major carmaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 extra per year in operating expenses than is estimated under laboratory tests.

“The bold statements that automakers often promote about their PHEV cars are obviously far from the mark,” commented a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating costs.”

Political Debate and Industry Pressure

Hybrid cars have lately been brought again into political debates as carmakers have lobbied the EU to weaken CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced intense lobbying from the car industry and resistance from member states with significant automotive manufacturing.

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

One independent energy policy specialist, who was unaffiliated with the study, described the analysis a “highly valuable addition” after a long period in which parts of the car sector argued there was insufficient information to accurately evaluate real-world CO2 output.

“The results show, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or diesel vehicles,” they stated. “All policy adjustments regarding PHEVs should be implemented with utmost care and considering this evidence.”