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Plug-in hybrid cars produce nearly 5x greater planet-heating pollution than official data indicate, as per a recent report.

Widening Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs release just 19% less CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a advocacy group. That differs significantly with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers studied information from in-vehicle fuel consumption meters of eight hundred thousand cars registered in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported emissions are falling,” said a senior analyst participating in the report. “That discrepancy is growing and poses a significant issue. As a result, PHEVs pollute almost as heavily as gasoline vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers linked most of the gap to overestimates of the “utility factor” – the percentage of miles driven in electric power compared to total distance. They determined that just 27% of travel was completed in EV mode, while official assumptions suggested 84%.

Additionally, when running in EV mode, pollution amounts were significantly higher than lab estimates. That occurred because electric motors were insufficiently powerful sufficient to operate alone, leading to engines burning fossil fuels for almost one-third of the distance completed in electric mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled four major automaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Additionally, owners of PHEVs could pay about €500 extra annually in operating costs than would be estimated under lab tests.

“The strong statements that automakers like to make about their PHEV cars are clearly way off the mark,” stated a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the planet and saving costs. Actually, PHEVs are little better than regular gas and diesel cars in terms of energy use, CO₂ emissions, and running costs.”

Policy Discussion and Industry Pressure

Hybrid cars have recently been drawn back into political debates as carmakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced heavy pressure from the car sector and resistance from EU countries with significant automotive industries.

Some senior politicians have suggested PHEVs as a potential “flexibility” option to introduce in the regulation.

One external energy economics specialist, who was not involved with the research, called the analysis a “very useful contribution” after a long period in which parts of the car industry claimed there was insufficient data to properly assess real-world emissions.

“These findings show, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert said. “All regulatory changes concerning PHEVs should be made with utmost caution and in the light of this data.”