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Plug-in hybrid electric vehicles produce almost five times greater planet-heating emissions than official data show, as per a recent report.

Growing Discrepancy In Lab and Actual Emissions

Data shows that PHEVs release just 19% lower CO₂ than traditional gas and diesel vehicles, based on analysis carried out by a advocacy group. This contrasts sharply with laboratory tests, which assumed a three-quarters decrease in emissions.

Analysts studied data from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in Europe between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official figures are falling,” stated a lead analyst participating in the study. “That gap is growing and poses a serious issue. Consequently, PHEVs pollute almost as heavily as gasoline cars.”

Key Factors Behind the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in electric power compared to total distance. The team determined that just a quarter of driving was completed in electric mode, while lab assumptions suggested over four-fifths.

Additionally, when operating in EV mode, emission levels were well above lab estimates. That occurred because EV motors were not strong sufficient to function alone, leading to engines burning fossil fuels for almost a third of the travel completed in EV mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV CO2 output enabled four large automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ targets.

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

“The strong statements that automakers like to make about their PHEV cars are obviously far from the truth,” commented a transport analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have recently been drawn again into policy discussions as carmakers have pressed the EU to relax CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced heavy pressure from the car industry and resistance from member states with significant automotive manufacturing.

Some high-level politicians have suggested plug-in hybrids as a potential “flexibility” option to include in the regulation.

One external energy policy expert, who was unaffiliated with the study, described the report a “highly valuable contribution” after years in which segments of the automotive industry argued there was insufficient information to accurately evaluate actual emissions.

“The results show, beyond any doubt, that the difference in official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel vehicles,” the expert said. “All policy changes regarding PHEVs should be implemented with utmost care and considering this data.”