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Plug-in hybrid electric vehicles emit almost five times more global warming pollution than official figures indicate, according to a recent analysis.

Growing Gap In Official and Real-World Emissions

Statistics reveals that PHEVs release just one-fifth less CO₂ than traditional petrol and diesel cars, according to research carried out by a advocacy group. This contrasts sharply with laboratory estimates, which suggested a 75% reduction in emissions.

Researchers examined data from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a senior analyst involved in the study. “This gap is growing and creates a serious problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Primary Reasons Driving the Discrepancy

Researchers linked most of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to overall mileage. They found that only 27% of travel was done in EV mode, whereas official estimates suggested over four-fifths.

Even, when operating in EV mode, emission levels were significantly higher than official estimates. That occurred because electric motors were not strong sufficient to operate alone, leading to engines using fossil fuels for nearly a third of the distance completed in EV mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four major carmaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs would spend approximately €500 more annually in operating expenses than would be assumed under lab tests.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Debate and Automotive Lobbying

Plug-in hybrid cars have recently been brought back into political debates as automakers have pressed the EU to relax CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with significant car industries.

Several high-level politicians have proposed PHEVs as a potential “compromise” option to include in the regulation.

An independent energy economics specialist, who was unaffiliated with the study, called the analysis a “very useful addition” after a long period in which parts of the car industry argued there was too little data to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ output is significantly larger than for petrol or diesel cars,” they said. “Any policy changes concerning PHEVs should be made with utmost care and in the light of this evidence.”