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Plug-in hybrid electric vehicles produce almost 5x more global warming pollution than official data indicate, according to a recent analysis.

Widening Discrepancy In Official and Actual Emissions

Data shows that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel cars, according to research conducted by a advocacy group. That differs significantly with laboratory estimates, which suggested a 75% decrease in pollution.

Analysts studied information from in-vehicle fuel consumption monitors of 800,000 cars registered in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from three and a half times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a senior researcher participating in the study. “This discrepancy is growing and creates a significant problem. As a result, PHEVs emit almost as heavily as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles driven in electric power relative to total distance. They determined that just 27% of driving was completed in electric mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in EV mode, pollution levels were well above lab projections. That occurred because electric motors were insufficiently powerful sufficient to function alone, leading to engines burning gasoline for nearly a third of the travel covered in EV mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV emissions enabled several large carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would pay approximately €500 more per year in running expenses than would be assumed under laboratory tests.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little improved than regular gas and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought again into political debates as carmakers have lobbied the EU to weaken CO₂ standards. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car sector and opposition from member states with large automotive industries.

Several high-level politicians have proposed PHEVs as a potential “flexibility” option to introduce in the regulation.

One independent energy policy specialist, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which parts of the automotive sector argued there was too little information to properly evaluate actual emissions.

“These findings show, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” the expert stated. “Any regulatory adjustments concerning PHEVs should be implemented with extreme care and in the light of this evidence.”