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PHEVs produce nearly five times more global warming emissions than lab-reported figures indicate, as per a recent analysis.

Growing Discrepancy Between Official and Real-World Emissions

Data reveals that PHEVs release only one-fifth less CO₂ than traditional gas and diesel vehicles, based on research carried out by a advocacy organization. This contrasts sharply with laboratory estimates, which assumed a 75% decrease in pollution.

Analysts studied information from onboard energy use monitors of 800,000 vehicles sold in Europe from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while official figures are falling,” stated a senior analyst participating in the report. “That gap is widening and poses a serious issue. As a result, PHEVs emit nearly as heavily as petrol cars.”

Key Factors Behind the Emissions Gap

Researchers linked the majority of the difference to overestimates of the “utility factor” – the percentage of miles travelled in battery mode compared to overall mileage. The team determined that only 27% of driving was completed in electric mode, while lab estimates assumed over four-fifths.

Even, when operating in EV mode, pollution amounts were well above official estimates. That happened because EV motors were not strong enough to operate alone, resulting to engines burning gasoline for almost a third of the travel covered in electric mode.

Regulatory and Economic Implications

According to calculations, the underestimation of PHEV CO2 output allowed several large carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would spend approximately €500 extra annually in operating expenses than is estimated under lab conditions.

“The bold statements that automakers often promote about their plug-in hybrid cars are obviously far from the mark,” stated a transport expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Pressure

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

Several senior politicians have proposed PHEVs as a potential “compromise” option to introduce in the regulation.

One external energy policy specialist, who was unaffiliated with the research, called the report a “very useful contribution” after years in which segments of the car industry claimed there was too little data to accurately evaluate real-world emissions.

“The results demonstrate, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or diesel vehicles,” they stated. “All regulatory changes regarding PHEVs should be implemented with utmost caution and considering this evidence.”