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PHEVs release almost five times more planet-heating pollution than lab-reported figures indicate, as per a recent report.

Widening Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs emit only 19% less CO₂ than conventional gas and diesel cars, based on research conducted by a non-profit group. This contrasts sharply with lab tests, which suggested a 75% decrease in emissions.

Analysts examined information from in-vehicle fuel consumption meters of 800,000 vehicles sold in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while official figures are falling,” said a lead researcher participating in the report. “That discrepancy is widening and creates a significant problem. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Key Reasons Behind the Discrepancy

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the percentage of miles travelled in electric power compared to total distance. The team found that only a quarter of travel was done in electric mode, whereas official assumptions assumed over four-fifths.

Even, when running in electric mode, emission amounts were well above official projections. That happened because electric motors were not strong sufficient to function alone, resulting to engines burning gasoline for almost one-third of the distance covered in electric mode.

Policy and Economic Consequences

According to estimates, the underestimation of PHEV CO2 output enabled several major carmaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 more per year in operating costs than is assumed under lab conditions.

“The bold claims that manufacturers like to make about their PHEV cars are obviously way off the truth,” commented a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting 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 operating costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into policy debates as carmakers have pressed the EU to relax CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced intense pressure from the automotive industry and opposition from member states with large automotive manufacturing.

Several senior politicians have suggested plug-in hybrids as a potential “compromise” option to introduce in the legislation.

An external energy policy specialist, who was unaffiliated with the study, described the analysis a “very useful addition” after a long period in which segments of the car industry argued there was too little data to properly evaluate actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional vehicles,” they said. “Any policy adjustments concerning PHEVs should be made with extreme caution and considering this evidence.”