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Plug-in hybrid electric vehicles emit almost five times greater global warming pollution than official figures indicate, according to a recent analysis.

Growing Discrepancy In Official and Real-World CO2 Output

Data shows that PHEVs release just 19% less CO₂ than conventional petrol and diesel vehicles, based on research carried out by a advocacy group. This contrasts sharply with laboratory tests, which suggested a three-quarters reduction in pollution.

Researchers examined information from onboard energy use monitors of 800,000 cars registered in the EU from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official figures are falling,” stated a lead researcher involved in the report. “That discrepancy is widening and poses a serious issue. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Primary Factors Behind the Discrepancy

Analysts linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric power relative to total distance. The team found that just a quarter of driving was completed in EV mode, while lab assumptions suggested 84%.

Additionally, when operating in electric mode, pollution amounts were well above official projections. That happened because EV motors were insufficiently powerful enough to function alone, resulting to engines using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Financial Consequences

According to estimates, the lowballing of PHEV CO2 output allowed several major automaker companies to escape over €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 extra annually in operating costs than would be estimated under laboratory conditions.

“The strong statements that automakers often promote about their PHEV cars are clearly far from the truth,” commented a transport expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving money. In reality, PHEVs are little improved than standard petrol and diesel cars in terms of energy use, CO₂ emissions, and running costs.”

Political Discussion and Industry Pressure

Hybrid vehicles have recently been brought again into policy discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A proposed ban on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from member states with large car manufacturing.

Several senior officials have proposed PHEVs as a possible “compromise” option to introduce in the regulation.

An independent energy economics expert, who was unaffiliated with the research, called the analysis a “highly valuable addition” after a long period in which parts of the car industry claimed there was too little data to accurately evaluate real-world emissions.

“These findings demonstrate, without question, that the difference between official and actual PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” the expert said. “Any regulatory changes regarding PHEVs should be made with extreme caution and in the light of this data.”