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Plug-in hybrid cars produce nearly 5x more planet-heating pollution than official data indicate, as per a new report.

Growing Gap Between Lab and Real-World Emissions

Data reveals that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel vehicles, based on analysis carried out by a advocacy organization. This contrasts sharply with lab estimates, which suggested a three-quarters reduction in emissions.

Analysts studied information from in-vehicle energy use meters of 800,000 vehicles sold in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” stated a senior analyst involved in the study. “This discrepancy is widening and creates a significant problem. As a result, PHEVs pollute almost as much as petrol cars.”

Key Factors Driving the Discrepancy

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric power compared to total distance. They determined that only a quarter of driving was done in electric mode, whereas official assumptions assumed over four-fifths.

Additionally, when running in EV mode, emission amounts were significantly higher than official estimates. This occurred because EV motors were insufficiently powerful sufficient to function independently, resulting to engines burning gasoline for nearly a third of the travel completed in EV mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV emissions allowed four major carmaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

Additionally, owners of PHEVs could spend about €500 more per year in running costs than would be assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid cars are obviously far from the truth,” commented a transport expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Political Debate and Industry Lobbying

Hybrid cars have lately been brought again into political debates as carmakers have lobbied the EU to weaken CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from member states with large automotive manufacturing.

Several senior politicians have proposed PHEVs as a potential “compromise” option to include in the legislation.

One external energy policy specialist, who was not involved with the research, described the analysis a “very useful contribution” after years in which segments of the car sector claimed there was insufficient data to accurately evaluate real-world emissions.

“The results demonstrate, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ emissions is much, much greater than for petrol or conventional cars,” the expert stated. “All regulatory adjustments concerning PHEVs should be made with utmost caution and considering that data.”