Plug-in Hybrid Cars Emit Nearly as Heavily as Petrol Vehicles, Report Reveals

Plug-in hybrid electric vehicles emit nearly 5x more global warming pollution than lab-reported data indicate, as per a new report.

Widening Discrepancy Between Lab and Real-World Emissions

Data reveals that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel cars, based on research conducted by a non-profit organization. That contrasts significantly with laboratory estimates, which assumed a three-quarters reduction in emissions.

Researchers studied information from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in Europe between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a lead analyst participating in the report. “This gap is growing and poses a serious problem. As a result, PHEVs emit nearly as much as petrol cars.”

Key Factors Driving the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in battery power relative to total distance. They found that just 27% of travel was completed in electric mode, whereas official estimates suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were significantly higher than lab estimates. That occurred because electric motors were not strong sufficient to function alone, leading to engines using fossil fuels for nearly a third of the travel completed in EV mode.

Regulatory and Financial Consequences

According to estimates, the lowballing of PHEV CO2 output enabled several large carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could spend approximately €500 more per year in running expenses than is assumed under lab conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are obviously way off the truth,” commented a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn again into political discussions as automakers have lobbied the EU to relax CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the car sector and opposition from EU countries with significant car industries.

Several high-level politicians have proposed PHEVs as a potential “compromise” option to introduce in the regulation.

An independent energy economics expert, who was not involved with the study, called the analysis a “highly valuable contribution” after years in which parts of the automotive industry argued there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the gap between lab and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional vehicles,” the expert said. “All policy changes regarding PHEVs should be implemented with extreme care and in the light of that data.”