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PHEVs produce almost five times more planet-heating pollution than official figures indicate, as per a recent report.

Growing Discrepancy In Official and Real-World Emissions

Data shows that PHEVs release just one-fifth lower CO₂ than conventional gas and diesel cars, based on research conducted by a non-profit organization. That contrasts significantly with laboratory tests, which suggested a 75% decrease in emissions.

Researchers studied information from onboard fuel consumption monitors of 800,000 vehicles registered in the EU from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while official emissions are decreasing,” said a lead analyst participating in the report. “This gap is widening and creates a significant problem. Consequently, PHEVs emit almost as much as gasoline vehicles.”

Key Reasons Behind the Discrepancy

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the percentage of miles driven in electric power compared to total mileage. They determined that just 27% of driving was completed in EV mode, whereas official estimates assumed 84%.

Even, when running in EV mode, pollution amounts were significantly higher than lab estimates. That happened because EV motors were not strong sufficient to operate alone, resulting to engines burning fossil fuels for nearly a third of the travel completed in EV mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV emissions enabled four major automaker groups to avoid over €5bn in fines from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 extra per year in running expenses than is estimated under lab conditions.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are clearly far from the truth,” commented a automotive analyst. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid cars have lately been drawn again into political discussions as carmakers have pressed the European Union to weaken CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with significant automotive manufacturing.

Several senior politicians have suggested plug-in hybrids as a possible “compromise” option to introduce in the legislation.

One external energy economics expert, who was not involved with the research, described the report a “very useful contribution” after a long period in which segments of the car industry argued there was insufficient information to accurately evaluate real-world CO2 output.

“These findings show, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is much, much larger than for petrol or diesel vehicles,” the expert said. “All policy changes concerning PHEVs should be implemented with extreme caution and considering this data.”