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PHEVs produce almost 5x greater global warming emissions than lab-reported data indicate, as per a recent report.

Growing Gap In Lab and Real-World CO2 Output

Data reveals that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel cars, according to analysis carried out by a advocacy organization. That contrasts sharply with laboratory estimates, which assumed a 75% decrease in pollution.

Analysts examined data from onboard fuel consumption monitors of 800,000 vehicles registered in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” stated a lead analyst involved in the report. “This discrepancy is growing and poses a serious problem. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Primary Factors Behind the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of miles travelled in battery mode compared to total distance. The team determined that only a quarter of travel was completed in EV mode, whereas lab estimates assumed 84%.

Even, when operating in electric mode, emission levels were well above lab estimates. That occurred because EV motors were not strong enough to function alone, leading to combustion motors burning gasoline for nearly one-third of the travel covered in electric mode.

Regulatory and Financial Consequences

According to estimates, the underestimation of PHEV emissions allowed four large carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 more annually in running costs than would be assumed under laboratory tests.

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the mark,” stated a automotive analyst. “Buyers are being misled into thinking that by buying a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy use, CO₂ emissions, and running expenses.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought back into policy discussions as carmakers have pressed the EU to weaken CO₂ standards. A proposed ban on new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and opposition from EU countries with large automotive manufacturing.

Several high-level officials have suggested plug-in hybrids as a possible “flexibility” solution to include in the legislation.

An external energy policy expert, who was not involved with the study, called the analysis a “very useful contribution” after years in which segments of the automotive sector argued there was insufficient data to properly assess actual emissions.

“The results demonstrate, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional vehicles,” the expert stated. “Any regulatory adjustments concerning PHEVs should be implemented with utmost care and in the light of that data.”