🔗 Share this article

PHEVs produce nearly five times more global warming pollution than lab-reported data indicate, as per a new analysis.

Widening Gap In Official and Real-World Emissions

Data reveals that PHEVs emit only one-fifth less CO₂ than traditional petrol and diesel vehicles, based on research conducted by a non-profit organization. That contrasts significantly with laboratory estimates, which suggested a three-quarters reduction in emissions.

Researchers studied data from onboard energy use monitors of 800,000 vehicles sold in Europe between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are decreasing,” said a lead researcher involved in the study. “That discrepancy is widening and poses a serious problem. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric mode compared to total distance. The team found that just 27% of travel was completed in electric mode, whereas official estimates suggested over four-fifths.

Additionally, when running in EV mode, emission levels were well above lab projections. That occurred because electric motors were not strong sufficient to function alone, resulting to combustion motors burning gasoline for nearly a third of the travel covered in EV mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV CO2 output allowed four large automaker companies to avoid over €5bn in penalties from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could pay approximately €500 extra per year in running costs than would be assumed under lab tests.

“The bold statements that manufacturers like to make about their PHEV cars are obviously far from the mark,” commented a automotive analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have recently been brought back into political debates as carmakers have lobbied the EU to weaken CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with large car manufacturing.

Several senior politicians have proposed PHEVs as a possible “flexibility” solution to include in the regulation.

One external energy policy expert, who was unaffiliated with the study, called the analysis a “highly valuable contribution” after a long period in which parts of the automotive industry claimed there was too little data to accurately assess real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or conventional vehicles,” they said. “Any regulatory changes concerning PHEVs should be made with extreme care and considering this evidence.”