🔗 Share this article

Plug-in hybrid cars emit almost 5x greater global warming emissions than lab-reported figures indicate, according to a new analysis.

Widening Gap Between Lab and Real-World CO2 Output

Statistics reveals that PHEVs release just 19% lower CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a non-profit group. This differs significantly with lab estimates, which suggested a 75% decrease in emissions.

Analysts studied data from in-vehicle fuel consumption monitors of 800,000 cars registered in Europe between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” said a lead analyst participating in the study. “That discrepancy is widening and poses a significant problem. As a result, PHEVs emit almost as heavily as petrol cars.”

Primary Reasons Behind the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in battery power relative to overall distance. The team determined that only a quarter of driving was completed in electric mode, whereas official estimates suggested 84%.

Additionally, when running in EV mode, emission amounts were significantly higher than official projections. This occurred because EV motors were insufficiently powerful enough to function alone, leading to combustion motors burning gasoline for nearly one-third of the travel covered in EV mode.

Regulatory and Economic Implications

According to calculations, the underestimation of PHEV CO2 output allowed four large automaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would spend about €500 more per year in operating costs than is estimated under lab tests.

“The strong statements that automakers often promote about their PHEV vehicles are clearly way off the truth,” commented a transport analyst. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and operating costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been brought again into political debates as automakers have lobbied the EU to relax CO₂ standards. A proposed ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and resistance from member states with large car manufacturing.

Some high-level politicians have suggested plug-in hybrids as a potential “flexibility” option to introduce in the regulation.

An external energy policy expert, who was unaffiliated with the research, described the report a “highly valuable contribution” after a long period in which segments of the car industry claimed there was insufficient information to properly evaluate actual emissions.

“These findings show, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel cars,” they stated. “All regulatory adjustments concerning PHEVs should be implemented with extreme care and in the light of this data.”