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PHEVs release nearly 5x more planet-heating emissions than official data indicate, as per a new report.

Growing Discrepancy Between Official and Real-World Emissions

Data shows that PHEVs emit just one-fifth less CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a non-profit organization. That differs significantly with laboratory estimates, which suggested a three-quarters decrease in pollution.

Researchers studied information from onboard fuel consumption monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official estimates, up from three and a half times in 2021.

“Actual emissions are increasing, while official figures are decreasing,” stated a senior analyst participating in the study. “This discrepancy is widening and poses a serious issue. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Factors Driving the Discrepancy

Analysts linked most of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in battery mode compared to overall mileage. They found that just a quarter of travel was completed in EV mode, whereas lab assumptions assumed 84%.

Additionally, when running in EV mode, emission levels were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful enough to function independently, resulting to combustion motors burning fossil fuels for nearly one-third of the travel completed in electric mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four major automaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would spend about €500 more per year in running costs than would be estimated under laboratory tests.

“The bold statements that automakers like to make about their PHEV vehicles are clearly way off the truth,” stated a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of energy use, CO₂ production, and running costs.”

Political Debate and Automotive Lobbying

Hybrid vehicles have recently been brought again into political debates as automakers have pressed the EU to weaken CO₂ targets. A proposed ban on new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with large car industries.

Several high-level officials have proposed PHEVs as a potential “flexibility” solution to introduce in the legislation.

One independent energy policy specialist, who was unaffiliated with the research, called the analysis a “very useful contribution” after years in which parts of the car sector argued there was too little data to properly assess actual emissions.

“These findings show, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ output is significantly greater than for gasoline or diesel vehicles,” the expert said. “All regulatory changes concerning PHEVs should be implemented with utmost care and in the light of this evidence.”