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Plug-in hybrid cars emit nearly 5x greater global warming emissions than lab-reported figures indicate, according to a recent analysis.

Growing Discrepancy Between Lab and Real-World Emissions

Statistics reveals that PHEVs emit only 19% lower CO₂ than traditional gas and diesel vehicles, based on research carried out by a non-profit organization. This contrasts sharply with lab tests, which suggested a three-quarters reduction in emissions.

Analysts studied data from onboard fuel consumption meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” said a senior researcher participating in the study. “This gap is growing and creates a significant issue. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Primary Reasons Behind the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the ratio of miles driven in battery mode relative to total distance. They determined that just a quarter of travel was done in electric mode, whereas official estimates suggested over four-fifths.

Even, when running in EV mode, pollution amounts were significantly higher than lab projections. That occurred because EV motors were not strong sufficient to function independently, leading to combustion motors burning fossil fuels for nearly one-third of the distance covered in electric mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV emissions allowed several major automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs could spend approximately €500 more annually in operating expenses than would be assumed under lab tests.

“The bold claims that manufacturers like to make about their PHEV vehicles are clearly way off the truth,” commented a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and saving costs. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have recently been brought back into political discussions as automakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with large automotive manufacturing.

Some senior officials have proposed PHEVs as a possible “flexibility” option to include in the regulation.

An independent energy policy expert, who was not involved with the research, described the analysis a “highly valuable addition” after a long period in which segments of the automotive sector argued there was insufficient data to accurately assess real-world CO2 output.

“The results demonstrate, without question, that the gap in official and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or conventional vehicles,” the expert said. “Any policy adjustments concerning PHEVs should be made with utmost caution and in the light of that data.”