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Plug-in hybrid electric vehicles release nearly 5x more planet-heating pollution than lab-reported data show, as per a recent report.

Widening Discrepancy Between Official and Real-World CO2 Output

Data shows that PHEVs release only one-fifth less CO₂ than traditional gas and diesel vehicles, according to research conducted by a non-profit organization. That contrasts sharply with lab estimates, which assumed a 75% decrease in pollution.

Analysts examined information from onboard fuel consumption monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” said a senior analyst participating in the study. “This gap is widening and poses a serious issue. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Key Reasons Driving the Discrepancy

Analysts linked the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery mode compared to overall mileage. The team determined that only a quarter of travel was done in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in EV mode, emission amounts were significantly higher than official projections. This occurred because electric motors were not strong sufficient to function alone, resulting to combustion motors using gasoline for almost a third of the distance covered in EV mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV CO2 output enabled several large automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 more per year in running expenses than is estimated under lab tests.

“The bold claims that automakers like to make about their PHEV vehicles are clearly far from the truth,” commented a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into policy debates as carmakers have pressed the EU to weaken CO₂ targets. A proposed ban on new combustion engine vehicles in 2035 has faced intense pressure from the automotive industry and opposition from member states with large automotive manufacturing.

Some senior officials have suggested plug-in hybrids as a possible “flexibility” solution to include in the regulation.

An external energy economics specialist, who was unaffiliated with the research, described the report a “highly valuable contribution” after years in which segments of the automotive industry claimed there was insufficient data to accurately evaluate actual CO2 output.

“The results show, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” the expert said. “All policy changes regarding PHEVs should be implemented with extreme caution and in the light of this evidence.”