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PHEVs release nearly five times greater global warming pollution than official data show, according to a new report.

Growing Discrepancy In Official and Real-World CO2 Output

Statistics reveals that PHEVs emit only 19% lower CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a advocacy group. That contrasts sharply with laboratory estimates, which assumed a three-quarters reduction in pollution.

Researchers studied information from in-vehicle energy use meters of 800,000 cars registered in the EU between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are decreasing,” stated a senior researcher involved in the report. “That discrepancy is growing and poses 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 gap to inflated estimates of the “electric driving share” – the percentage of miles driven in electric mode relative to total distance. The team determined that only a quarter of driving was done in electric mode, while official estimates assumed 84%.

Additionally, when running in electric mode, pollution amounts were significantly higher than official projections. This occurred because EV motors were insufficiently powerful enough to function independently, leading to engines burning gasoline for nearly a third of the distance covered in EV mode.

Policy and Economic Implications

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

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

“The bold statements that automakers like to make about their plug-in hybrid cars are clearly way off the mark,” stated a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little better than regular gas and diesel cars in terms of energy consumption, CO₂ production, and operating expenses.”

Political Debate and Industry Pressure

Plug-in hybrid cars have lately been brought back into policy debates as automakers have lobbied the European Union to weaken CO₂ standards. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with significant automotive manufacturing.

Some senior politicians have proposed PHEVs as a potential “compromise” option to introduce in the regulation.

An independent energy policy expert, who was not involved with the research, described the report a “very useful addition” after years in which parts of the car sector argued there was too little information to properly assess real-world emissions.

“These findings demonstrate, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ emissions is much, much larger than for petrol or diesel cars,” the expert stated. “Any regulatory changes regarding PHEVs should be implemented with extreme care and in the light of that data.”