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Plug-in hybrid cars release almost five times more global warming emissions than lab-reported data show, as per a new analysis.

Widening Gap In Official and Real-World CO2 Output

Data reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel vehicles, based on research conducted by a non-profit group. This differs significantly with laboratory tests, which assumed a three-quarters reduction in emissions.

Analysts studied information from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” stated a lead analyst participating in the report. “This discrepancy is widening and creates a significant issue. Consequently, PHEVs pollute nearly as heavily as petrol cars.”

Key Reasons Driving the Discrepancy

Researchers linked most of the gap to inflated estimates of the “electric driving share” – the ratio of miles driven in electric power relative to overall distance. The team found that only 27% of travel was done in electric mode, whereas lab estimates suggested 84%.

Additionally, when running in electric mode, emission amounts were significantly higher than lab projections. That occurred because EV motors were insufficiently powerful sufficient to operate alone, resulting to combustion motors burning gasoline for nearly one-third of the travel completed in electric mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV emissions allowed several large automaker groups to avoid over €5bn in fines between 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend approximately €500 more per year in running costs than is estimated under lab tests.

“The bold claims that automakers often promote about their PHEV cars are obviously far from the mark,” commented a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little better than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been brought again into policy discussions as carmakers have pressed the EU to relax CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and opposition from EU countries with large automotive manufacturing.

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

An independent energy economics specialist, who was not involved with the study, called the analysis a “highly valuable contribution” after a long period in which parts of the car industry claimed there was too little information to accurately assess real-world CO2 output.

“The results demonstrate, without question, that the gap between official and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or conventional cars,” they stated. “Any regulatory changes concerning PHEVs should be implemented with utmost care and in the light of that evidence.”