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Plug-in hybrid cars produce nearly five times greater global warming emissions than official figures indicate, according to a recent analysis.

Growing Gap In Lab and Actual Emissions

Data shows that PHEVs release just one-fifth less CO₂ than conventional petrol and diesel cars, according to analysis carried out by a advocacy organization. That contrasts sharply with lab tests, which assumed a three-quarters reduction in emissions.

Analysts examined data from onboard fuel consumption meters of 800,000 cars registered in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from three and a half times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” stated a lead analyst participating in the report. “That gap is growing and poses a serious issue. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Key Factors Behind the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in electric mode compared to total mileage. The team found that just 27% of driving was completed in EV mode, whereas lab estimates assumed over four-fifths.

Additionally, when operating in electric mode, pollution levels were well above lab projections. This happened because electric motors were insufficiently powerful sufficient to operate independently, resulting to engines using fossil fuels for nearly one-third of the distance completed in electric mode.

Regulatory and Economic Consequences

Based on calculations, the underestimation of PHEV emissions allowed four major automaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could spend about €500 extra per year in running expenses than would be assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” commented a automotive analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Political Debate and Industry Lobbying

Hybrid cars have recently been brought again into political discussions as carmakers have pressed the European Union to weaken CO₂ targets. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and resistance from member states with significant car industries.

Some senior officials have proposed PHEVs as a possible “compromise” solution to include in the regulation.

An independent energy policy specialist, who was unaffiliated with the research, described the report a “highly valuable addition” after a long period in which parts of the automotive sector argued there was too little information to accurately evaluate real-world CO2 output.

“These findings show, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel cars,” the expert stated. “All policy changes concerning PHEVs should be implemented with utmost care and considering that evidence.”