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Plug-in hybrid electric vehicles emit almost five times greater planet-heating pollution than lab-reported data show, as per a recent analysis.

Growing Discrepancy Between Lab and Actual CO2 Output

Statistics reveals that PHEVs release only 19% less CO₂ than traditional petrol and diesel vehicles, based on research conducted by a non-profit organization. This contrasts significantly with laboratory tests, which assumed a three-quarters decrease in emissions.

Analysts studied data from onboard fuel consumption meters of 800,000 vehicles registered in Europe from 2021 and 2023. They discovered 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 CO2 output are increasing, while official figures are falling,” stated a lead analyst participating in the report. “This gap is widening and creates a significant problem. Consequently, PHEVs pollute nearly as heavily as petrol cars.”

Primary Factors Driving the Discrepancy

Analysts linked the majority of the gap to overestimates of the “utility factor” – the percentage of miles travelled in electric power compared to total mileage. The team determined that just 27% of driving was done in electric mode, while official assumptions assumed over four-fifths.

Even, when running in EV mode, pollution levels were well above lab projections. This happened because EV motors were not strong enough to operate independently, resulting to combustion motors burning fossil fuels for almost one-third of the distance covered in EV mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output allowed four large automaker companies to escape more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs would spend about €500 more annually in running expenses than would be estimated under lab conditions.

“The strong statements that manufacturers often promote about their PHEV vehicles are clearly far from the mark,” stated a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Debate and Automotive Lobbying

Plug-in hybrid cars have recently been brought again into political debates as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced intense lobbying from the car industry and resistance from EU countries with large automotive manufacturing.

Some senior politicians have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

An independent energy policy specialist, who was unaffiliated with the research, described the report a “highly valuable addition” after a long period in which segments of the automotive industry argued there was too little data to accurately assess real-world emissions.

“The results show, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel vehicles,” the expert stated. “All regulatory adjustments regarding PHEVs should be implemented with extreme caution and considering that evidence.”