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Plug-in hybrid cars produce nearly 5x greater planet-heating emissions than official data show, as per a new report.

Widening Gap Between Lab and Real-World CO2 Output

Statistics reveals that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel cars, according to analysis conducted by a advocacy group. That contrasts sharply with lab estimates, which suggested a 75% reduction in pollution.

Analysts studied information from onboard fuel consumption monitors of eight hundred thousand vehicles registered in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are falling,” stated a lead analyst participating in the report. “This gap is widening and poses a serious problem. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in battery power relative to overall mileage. They found that only a quarter of travel was completed in EV mode, while lab assumptions assumed over four-fifths.

Even, when operating in electric mode, pollution levels were well above official projections. That happened because EV motors were not strong enough to function alone, resulting to combustion motors using fossil fuels for nearly one-third of the travel completed in electric mode.

Policy and Financial Consequences

Based on estimates, the lowballing of PHEV emissions allowed several large automaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ targets.

Additionally, owners of PHEVs could spend about €500 extra per year in operating expenses than would be estimated under lab tests.

“The strong claims that manufacturers often promote about their PHEV cars are clearly far from the truth,” stated a transport expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn again into policy debates as carmakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with significant automotive manufacturing.

Several senior politicians have suggested plug-in hybrids as a potential “compromise” option to include in the regulation.

An independent energy economics expert, who was not involved with the study, described the report a “highly valuable contribution” after a long period in which segments of the automotive industry argued there was insufficient data to properly assess actual emissions.

“These findings show, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ emissions 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 considering this data.”