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Plug-in hybrid electric vehicles emit nearly five times more global warming emissions than lab-reported data show, as per a recent report.

Widening Discrepancy Between Lab and Real-World Emissions

Statistics reveals that PHEVs emit only 19% lower CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a advocacy organization. This contrasts sharply with lab estimates, which assumed a three-quarters decrease in emissions.

Analysts examined information from in-vehicle fuel consumption monitors of 800,000 cars sold in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from three and a half times in 2021.

“Actual emissions are increasing, while official figures are falling,” said a lead analyst involved in the study. “This gap is growing and creates a serious problem. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric power relative to overall distance. The team found that just a quarter of travel was done in electric mode, whereas lab assumptions assumed over four-fifths.

Even, when running in electric mode, emission amounts were well above lab estimates. That happened because EV motors were insufficiently powerful enough to operate alone, resulting to engines using gasoline for nearly a third of the distance completed in EV mode.

Regulatory and Economic Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled four large carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 more annually in operating costs than would be estimated under lab conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid cars are obviously far from the truth,” commented a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and running costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been brought again into policy debates as carmakers have pressed the EU to weaken CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the car sector and opposition from member states with large car industries.

Several high-level officials have suggested PHEVs as a potential “flexibility” solution to introduce in the regulation.

An external energy policy specialist, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after years in which segments of the car industry claimed there was too little information to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or conventional cars,” they said. “Any regulatory changes regarding PHEVs should be made with utmost care and in the light of this evidence.”