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PHEVs release nearly 5x more global warming emissions than official data indicate, as per a new report.

Widening Gap Between Lab and Real-World Emissions

Data reveals that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a non-profit organization. This contrasts significantly with lab tests, which assumed a three-quarters reduction in pollution.

Analysts studied data from in-vehicle energy use monitors of eight hundred thousand vehicles registered in Europe from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” stated a lead researcher participating in the study. “This discrepancy is growing and creates a serious issue. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Key Factors Behind the Discrepancy

Analysts linked most of the difference to overestimates of the “utility factor” – the ratio of miles travelled in battery power compared to overall distance. The team found that only a quarter of driving was done in electric mode, whereas official estimates suggested over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than official projections. That happened because electric motors were not strong sufficient to function alone, resulting 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 allowed several large automaker groups to escape over €5bn in fines between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 more annually in operating expenses than would be assumed under laboratory conditions.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are obviously far from the truth,” stated a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and running costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have lately been brought again into political debates as carmakers have lobbied the EU to relax CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced intense lobbying from the car industry and opposition from member states with large automotive manufacturing.

Some senior officials have proposed PHEVs as a potential “flexibility” option to include in the regulation.

One independent energy economics expert, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which parts of the car sector argued there was too little information to accurately assess real-world emissions.

“These findings demonstrate, beyond any doubt, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” they said. “Any regulatory adjustments concerning PHEVs should be implemented with extreme caution and considering that data.”