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Plug-in hybrid electric vehicles produce nearly 5x greater planet-heating emissions than lab-reported data show, as per a recent report.

Widening Discrepancy In Official and Real-World Emissions

Statistics reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, based on analysis conducted by a advocacy group. That contrasts significantly with laboratory estimates, which assumed a three-quarters decrease in emissions.

Analysts studied data from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” stated a senior analyst participating in the report. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Key Factors Driving the Discrepancy

Analysts linked the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery mode relative to overall mileage. The team determined that only 27% of travel was completed in electric mode, whereas official assumptions suggested over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than official estimates. This happened because electric motors were insufficiently powerful sufficient to operate alone, resulting to combustion motors using gasoline for nearly a third of the travel covered in electric mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several major automaker groups to avoid more than €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 extra annually in running expenses than would be estimated under laboratory tests.

“The bold statements that automakers like to make about their PHEV cars are clearly far from the mark,” stated a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Debate and Industry Pressure

Hybrid cars have recently been brought back into policy debates as automakers have lobbied the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the car sector and resistance from member states with large car manufacturing.

Several senior politicians have proposed plug-in hybrids as a potential “flexibility” solution to introduce in the legislation.

One external energy policy specialist, who was not involved with the study, described the report a “very useful contribution” after a long period in which parts of the car sector claimed there was insufficient information to properly assess real-world emissions.

“These findings show, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or conventional vehicles,” they said. “All policy adjustments regarding PHEVs should be implemented with utmost care and in the light of that data.”