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PHEVs emit almost 5x more global warming pollution than official figures show, according to a new report.

Widening Gap In Official and Real-World CO2 Output

Data shows that PHEVs emit just 19% lower CO₂ than traditional gas and diesel vehicles, according to research conducted by a advocacy group. This contrasts sharply with lab estimates, which assumed a three-quarters decrease in emissions.

Researchers studied information from onboard energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. The team 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 CO2 output are increasing, while official figures are falling,” said a lead researcher involved in the study. “This gap is widening and creates a significant problem. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Reasons Behind the Discrepancy

Researchers linked most of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric mode relative to total mileage. The team found that only a quarter of travel was completed in EV mode, while lab assumptions suggested 84%.

Even, when operating in electric mode, emission levels were well above lab estimates. This occurred because electric motors were insufficiently powerful enough to function alone, resulting to engines using gasoline for nearly one-third of the travel covered in EV mode.

Policy and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled several large automaker companies to escape over €5bn in penalties from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 extra annually in operating costs than is estimated under lab conditions.

“The strong statements that manufacturers like to make about their plug-in hybrid cars are clearly far from the truth,” commented a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Debate and Automotive Pressure

Hybrid cars have lately been brought again into political discussions as carmakers have lobbied the EU to relax CO₂ targets. A proposed ban on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from member states with large automotive industries.

Several high-level politicians have suggested plug-in hybrids as a potential “compromise” option to introduce in the regulation.

One external energy economics specialist, who was unaffiliated with the study, described the analysis a “highly valuable addition” after a long period in which segments of the car sector argued there was insufficient data to accurately evaluate real-world emissions.

“The results show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” they stated. “Any regulatory adjustments regarding PHEVs should be implemented with extreme caution and considering that evidence.”