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Plug-in hybrid cars emit almost five times greater global warming pollution than lab-reported data show, according to a recent analysis.

Widening Gap In Official and Actual CO2 Output

Statistics reveals that PHEVs emit only 19% lower CO₂ than conventional petrol and diesel vehicles, according to analysis carried out by a non-profit group. This contrasts significantly with lab estimates, which assumed a 75% decrease in pollution.

Analysts studied information from onboard energy use meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are falling,” said a senior analyst involved in the study. “This discrepancy is growing and poses a serious issue. Consequently, PHEVs pollute almost as much as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of miles travelled in battery mode relative to total mileage. The team determined that only a quarter of travel was completed in EV mode, whereas lab estimates suggested over four-fifths.

Even, when running in EV mode, emission amounts were well above official estimates. This happened because EV motors were not strong enough to operate independently, leading to engines using gasoline for nearly one-third of the distance completed in electric mode.

Regulatory and Economic Consequences

Based on estimates, the underestimation of PHEV emissions enabled four major automaker companies to escape more than €5bn in fines between 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay about €500 extra annually in running expenses than would be estimated under laboratory tests.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are obviously far from the mark,” stated a automotive expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy consumption, CO₂ production, and running costs.”

Political Discussion and Industry Pressure

Hybrid cars have recently been brought back into policy debates as automakers have lobbied the European Union to relax CO₂ standards. A planned ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with significant automotive manufacturing.

Some high-level politicians have suggested plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

An independent energy economics specialist, who was unaffiliated with the study, called the report a “very useful addition” after a long period in which parts of the car sector claimed there was too little information to accurately assess real-world CO2 output.

“These findings show, beyond any doubt, that the difference in official and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or diesel vehicles,” the expert stated. “Any policy adjustments regarding PHEVs should be made with utmost caution and in the light of this data.”