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PHEVs release nearly 5x more planet-heating pollution than lab-reported data show, according to a recent report.

Growing Gap Between Official and Real-World Emissions

Data reveals that PHEVs emit only 19% less CO₂ than conventional petrol and diesel vehicles, based on analysis conducted by a advocacy group. That differs significantly with lab estimates, which suggested a 75% reduction in emissions.

Researchers examined data from in-vehicle energy use monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while official emissions are falling,” said a senior analyst involved in the study. “This discrepancy is growing and creates a serious issue. Consequently, PHEVs emit nearly as much as petrol cars.”

Primary Factors Behind the Emissions Gap

Analysts linked the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in electric power compared to overall distance. The team found that only a quarter of travel was done in electric mode, while lab estimates assumed 84%.

Additionally, when operating in EV mode, emission amounts were well above lab estimates. This occurred because EV motors were insufficiently powerful sufficient to function independently, leading to combustion motors using fossil fuels for almost one-third of the distance completed in EV mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV emissions allowed four large carmaker companies to avoid more than €5bn in fines between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could pay approximately €500 extra per year in running expenses than would be estimated under lab tests.

“The bold statements that automakers often promote about their PHEV cars are obviously way off the mark,” stated a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have lately been drawn back into political discussions as carmakers have lobbied the EU to weaken CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the car industry and opposition from EU countries with large car manufacturing.

Several senior politicians have proposed PHEVs as a possible “flexibility” solution to introduce in the regulation.

One external energy policy specialist, who was not involved with the study, described the analysis a “highly valuable contribution” after years in which segments of the automotive sector claimed there was insufficient information to accurately evaluate actual CO2 output.

“These findings demonstrate, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel vehicles,” they stated. “Any regulatory changes concerning PHEVs should be made with extreme care and considering that evidence.”