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PHEVs emit almost five times more planet-heating pollution than official data show, as per a recent report.

Widening Discrepancy In Official and Real-World CO2 Output

Data shows that PHEVs emit just 19% less CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a non-profit organization. That contrasts significantly with laboratory tests, which suggested a three-quarters reduction in pollution.

Researchers examined data from onboard fuel consumption monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported emissions are falling,” stated a senior researcher participating in the report. “That discrepancy is widening and poses a significant problem. Consequently, PHEVs pollute almost as much as petrol cars.”

Primary Factors Behind the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric power compared to total mileage. The team found that only a quarter of driving was completed in electric mode, while official estimates suggested over four-fifths.

Additionally, when running in electric mode, pollution amounts were significantly higher than lab projections. That occurred because EV motors were not strong sufficient to function independently, resulting to combustion motors burning fossil fuels for almost a third of the travel completed in electric mode.

Regulatory and Financial Implications

According to estimates, the underestimation of PHEV emissions enabled four major automaker companies to avoid more than €5bn in fines from 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs could pay about €500 extra per year in operating expenses than is estimated under laboratory tests.

“The strong claims that automakers often promote about their plug-in hybrid cars are clearly far from the truth,” commented a transport analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of energy use, CO₂ emissions, and running expenses.”

Political Debate and Industry Lobbying

Hybrid cars have recently been drawn back into policy debates as carmakers have pressed the EU to relax CO₂ targets. A proposed ban on new internal combustion vehicles in 2035 has faced heavy pressure from the car sector and resistance from member states with significant car manufacturing.

Some senior officials have suggested PHEVs as a potential “compromise” solution to introduce in the regulation.

One external energy policy expert, who was unaffiliated with the research, described the report a “very useful addition” after a long period in which parts of the car industry argued there was insufficient information to accurately evaluate real-world CO2 output.

“The results demonstrate, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel vehicles,” they said. “All regulatory changes concerning PHEVs should be implemented with utmost care and considering this evidence.”