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Plug-in hybrid cars produce almost five times more global warming pollution than lab-reported figures indicate, according to a recent report.

Growing Discrepancy In Official and Real-World CO2 Output

Statistics shows that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel vehicles, based on analysis conducted by a non-profit organization. This differs sharply with laboratory tests, which suggested a three-quarters reduction in emissions.

Analysts examined data from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” stated a lead analyst involved in the study. “This discrepancy is widening and poses a significant problem. As a result, PHEVs pollute nearly as much as gasoline cars.”

Key Reasons Behind the Discrepancy

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the percentage of miles driven in battery mode compared to overall distance. They determined that just 27% of travel was completed in EV mode, while official assumptions suggested 84%.

Even, when running in EV mode, emission amounts were well above official projections. That occurred because EV motors were insufficiently powerful enough to function independently, leading to engines burning fossil fuels for almost one-third of the distance completed in electric mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV emissions enabled several large automaker groups to avoid over €5bn in penalties from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

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

“The strong claims that automakers often promote about their PHEV cars are clearly far from the truth,” stated a transport analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and running expenses.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn back into political debates as carmakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on new internal combustion cars in 2035 has faced heavy pressure from the car sector and opposition from EU countries with large car manufacturing.

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

An independent energy policy expert, who was not involved with the study, described the analysis a “highly valuable contribution” after years in which parts of the automotive sector argued there was insufficient information to properly evaluate real-world CO2 output.

“The results demonstrate, without question, that the difference between official and actual PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel vehicles,” they stated. “All regulatory adjustments concerning PHEVs should be implemented with utmost care and in the light of that evidence.”