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Plug-in hybrid electric vehicles release almost 5x more global warming pollution than official figures show, as per a recent analysis.

Widening Discrepancy In Lab and Actual Emissions

Data shows that PHEVs release only 19% lower CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a advocacy organization. This contrasts sharply with lab tests, which assumed a three-quarters reduction in emissions.

Researchers studied information from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. The team found that real-world CO₂ output 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 decreasing,” stated a senior researcher involved in the report. “This gap is growing and poses a significant issue. Consequently, PHEVs pollute almost as much as petrol cars.”

Key Reasons Driving the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the percentage of miles driven in electric mode compared to overall distance. They found that only a quarter of travel was completed in EV mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in electric mode, emission levels were well above official projections. This happened because EV motors were insufficiently powerful sufficient to operate independently, leading to engines burning gasoline for almost a third of the travel covered in electric mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV CO2 output enabled several large automaker groups to avoid more than €5bn in fines from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

Additionally, owners of PHEVs could spend about €500 more per year in operating expenses than would be estimated under laboratory tests.

“The strong claims that manufacturers often promote 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 helping the planet and cutting money. Actually, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Discussion and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn back into political debates as automakers have lobbied the EU to weaken CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced intense pressure from the automotive sector and opposition from member states with large automotive manufacturing.

Several high-level politicians have proposed plug-in hybrids as a potential “flexibility” solution to introduce in the legislation.

An external energy economics specialist, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after a long period in which parts of the automotive sector claimed there was insufficient data to accurately assess actual CO2 output.

“The results show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” the expert stated. “All regulatory adjustments concerning PHEVs should be made with extreme care and considering this evidence.”