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Plug-in hybrid cars produce nearly 5x greater planet-heating emissions than official data show, as per a new analysis.

Widening Discrepancy In Lab and Real-World Emissions

Data reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel vehicles, according to research conducted by a advocacy group. This differs significantly with laboratory estimates, which assumed a three-quarters decrease in pollution.

Researchers examined information from onboard energy use meters of eight hundred thousand cars registered in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are decreasing,” said a senior analyst participating in the study. “This discrepancy is growing and poses a serious issue. Consequently, PHEVs pollute almost as much as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the percentage of miles travelled in electric power relative to total distance. They determined that just 27% of driving was done in electric mode, whereas lab estimates assumed over four-fifths.

Even, when running in EV mode, emission levels were well above lab projections. That occurred because EV motors were insufficiently powerful sufficient to function alone, resulting to engines burning gasoline for almost one-third of the travel covered in EV mode.

Policy and Economic Consequences

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

Additionally, drivers of PHEVs would pay about €500 extra per year in operating expenses than would be estimated under lab conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the mark,” commented a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are only slightly improved than regular gas and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Lobbying

Plug-in hybrid cars have lately been drawn again into policy debates as carmakers have lobbied the EU to relax CO₂ targets. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the car sector and resistance from EU countries with large automotive manufacturing.

Some senior politicians have proposed plug-in hybrids as a potential “compromise” solution to include in the regulation.

An external energy policy expert, who was not involved with the study, described the report a “highly valuable addition” after a long period in which segments of the car sector argued there was insufficient information to properly assess actual emissions.

“These findings demonstrate, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ emissions is much, much larger than for gasoline or conventional cars,” the expert said. “Any policy adjustments regarding PHEVs should be implemented with utmost caution and in the light of that evidence.”