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Plug-in hybrid cars emit almost five times more planet-heating emissions than official figures indicate, as per a recent report.

Growing Gap In Lab and Actual Emissions

Statistics reveals that PHEVs emit only one-fifth lower CO₂ than traditional gas and diesel cars, based on analysis carried out by a advocacy organization. This contrasts significantly with laboratory estimates, which assumed a 75% decrease in pollution.

Analysts examined data from onboard energy use meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are falling,” said a lead researcher participating in the study. “This gap is widening and poses a significant issue. As a result, PHEVs emit almost as much as petrol cars.”

Key Factors Behind the Emissions Gap

Analysts attributed most of the difference to overestimates of the “electric driving share” – the percentage of miles driven in electric power relative to overall mileage. They found that just 27% of driving was completed in EV mode, whereas official estimates suggested 84%.

Additionally, when operating in EV mode, pollution amounts were well above official estimates. That occurred because EV motors were not strong enough to operate independently, leading to combustion motors burning gasoline for nearly a third of the travel completed in EV mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV emissions allowed four major automaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 more per year in operating expenses than would be estimated under lab conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the truth,” stated a transport expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running expenses.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been drawn back into policy debates as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car industry and resistance from member states with significant car industries.

Some high-level officials have proposed plug-in hybrids as a potential “compromise” option to include in the regulation.

An independent energy economics expert, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after years in which parts of the automotive industry claimed there was insufficient information to accurately evaluate actual CO2 output.

“The results show, without question, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or conventional cars,” the expert stated. “All regulatory changes regarding PHEVs should be implemented with utmost caution and considering this evidence.”