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PHEVs emit almost 5x more global warming emissions than lab-reported data indicate, as per a new analysis.

Growing Discrepancy Between Lab and Real-World CO2 Output

Statistics shows that PHEVs release just 19% lower CO₂ than traditional gas and diesel cars, based on analysis conducted by a non-profit organization. That contrasts sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers studied information from onboard fuel consumption monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official figures are falling,” stated a lead analyst participating in the study. “That gap is growing and creates a significant problem. Consequently, PHEVs pollute nearly as heavily as petrol cars.”

Primary Reasons Driving the Emissions Gap

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in battery power compared to overall distance. They determined that only a quarter of travel was done in electric mode, whereas official estimates assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were significantly higher than lab estimates. This occurred because electric motors were insufficiently powerful enough to operate alone, leading to combustion motors using fossil fuels for nearly a third of the distance covered in EV mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV emissions allowed four large carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay about €500 more per year in running costs than is estimated under lab conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the mark,” commented a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are helping the planet and saving costs. In reality, PHEVs are little better than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Lobbying

Plug-in hybrid cars have lately been drawn back into policy debates as carmakers have pressed the EU to relax CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with significant automotive manufacturing.

Some high-level politicians have proposed PHEVs as a possible “flexibility” option to introduce in the legislation.

An external energy policy specialist, who was not involved with the research, called the analysis a “highly valuable addition” after a long period in which segments of the automotive sector argued there was insufficient data to accurately evaluate real-world CO2 output.

“The results show, without question, that the gap between lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for petrol or conventional cars,” the expert stated. “All regulatory changes concerning PHEVs should be implemented with utmost caution and in the light of this data.”