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Plug-in hybrid electric vehicles produce almost five times more global warming emissions than lab-reported figures show, as per a recent report.

Growing Discrepancy In Lab and Actual Emissions

Statistics reveals that PHEVs release just one-fifth less CO₂ than conventional petrol and diesel cars, based on research carried out by a advocacy organization. That contrasts sharply with lab tests, which assumed a 75% decrease in emissions.

Analysts studied data from onboard energy use monitors of 800,000 vehicles registered in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” stated a lead researcher participating in the report. “This gap is growing and poses a serious issue. As a result, PHEVs emit almost as heavily as gasoline cars.”

Key Factors Behind the Emissions Gap

Researchers linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric mode relative to overall mileage. They determined that only a quarter of travel was completed in electric mode, while official assumptions suggested over four-fifths.

Even, when running in electric mode, pollution levels were significantly higher than lab estimates. That happened because EV motors were insufficiently powerful enough to function alone, leading to engines burning gasoline for almost a third of the distance completed in EV mode.

Policy and Economic Consequences

Based on estimates, the underestimation of PHEV emissions enabled several large automaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs could pay approximately €500 more per year in running costs than is estimated under lab conditions.

“The strong claims that manufacturers like to make about their PHEV vehicles are clearly way off the mark,” commented a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of fuel use, CO₂ production, and running costs.”

Policy Debate and Industry Pressure

Plug-in hybrid cars have recently been drawn again into political debates as automakers have pressed the EU to weaken CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive sector and resistance from EU countries with large automotive industries.

Some high-level officials have suggested plug-in hybrids as a possible “flexibility” option to introduce in the regulation.

An external energy policy specialist, who was unaffiliated with the study, described the report a “highly valuable contribution” after a long period in which segments of the car sector claimed there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, without question, that the gap between lab and real-world PHEV energy use and CO₂ emissions is much, much greater than for petrol or diesel cars,” they said. “Any regulatory adjustments concerning PHEVs should be implemented with extreme care and in the light of this evidence.”