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Plug-in hybrid cars release nearly 5x more global warming pollution than official figures show, according to a recent report.

Widening Gap Between Official and Actual Emissions

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than traditional petrol and diesel cars, based on research carried out by a advocacy organization. This contrasts significantly with lab tests, which assumed a three-quarters reduction in pollution.

Researchers studied information from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported emissions are decreasing,” said a lead analyst involved in the report. “This gap is growing and poses a significant problem. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Researchers linked most of the difference to overestimates of the “electric driving share” – the percentage of kilometers driven in battery power compared to total mileage. The team determined that only 27% of travel was done in electric mode, whereas lab assumptions assumed over four-fifths.

Even, when running in EV mode, pollution amounts were significantly higher than official projections. This occurred because electric motors were not strong sufficient to operate independently, leading to engines using fossil fuels for nearly a third of the distance completed in EV mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV emissions enabled four large carmaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 extra per year in operating expenses than is estimated under laboratory conditions.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are obviously way off the mark,” stated a transport analyst. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little better than regular petrol and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Political Discussion and Automotive Pressure

Plug-in hybrid cars have lately been drawn again into political discussions as automakers have pressed the EU to weaken CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and resistance from EU countries with significant automotive industries.

Several senior officials have proposed PHEVs as a potential “flexibility” option to include in the regulation.

One external energy policy expert, who was not involved with the research, called the analysis a “very useful addition” after years in which segments of the automotive industry argued there was too little information to properly evaluate real-world CO2 output.

“The results show, without question, that the gap between lab and real-world PHEV energy use and CO₂ emissions is significantly larger than for gasoline or diesel cars,” they stated. “All regulatory adjustments regarding PHEVs should be made with utmost care and considering this data.”