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Plug-in hybrid electric vehicles emit almost five times greater global warming pollution than official data indicate, according to a new analysis.

Widening Gap In Lab and Actual CO2 Output

Data shows that PHEVs release just 19% less CO₂ than traditional gas and diesel vehicles, according to analysis conducted by a advocacy group. This differs significantly with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers examined information from in-vehicle energy use meters of eight hundred thousand vehicles registered in Europe between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” said a lead analyst involved in the study. “That discrepancy is growing and poses a serious problem. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Key Factors Driving the Emissions Gap

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the ratio of miles driven in battery power compared to total distance. They found that just a quarter of travel was completed in electric mode, whereas lab estimates suggested over four-fifths.

Even, when operating in electric mode, pollution levels were well above official estimates. That occurred because EV motors were insufficiently powerful enough to operate independently, resulting to engines burning gasoline for almost one-third of the travel completed in EV mode.

Regulatory and Economic Implications

According to calculations, the lowballing of PHEV emissions allowed several major automaker groups to avoid over €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 extra per year in running costs than is assumed under lab conditions.

“The strong statements that manufacturers often promote about their PHEV vehicles are obviously way off the mark,” commented a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting money. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Policy Debate and Industry Pressure

Hybrid vehicles have recently been drawn again into political debates as carmakers have pressed the EU to relax CO₂ targets. A proposed prohibition on new combustion engine cars in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with large car manufacturing.

Some high-level politicians have proposed PHEVs as a potential “flexibility” option to introduce in the legislation.

One independent energy policy expert, who was unaffiliated with the research, described the analysis a “very useful contribution” after years in which segments of the car industry argued there was too little data to accurately evaluate actual CO2 output.

“These findings show, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or conventional cars,” the expert stated. “Any policy adjustments concerning PHEVs should be implemented with extreme care and considering this evidence.”