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Plug-in hybrid electric vehicles release nearly 5x greater global warming emissions than lab-reported data show, as per a recent analysis.

Growing Gap Between Official and Real-World CO2 Output

Data reveals that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a advocacy organization. That differs significantly with lab tests, which assumed a 75% decrease in pollution.

Analysts studied data from onboard energy use meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” said a senior analyst involved in the study. “This discrepancy is widening and creates a significant issue. Consequently, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Factors Behind the Emissions Gap

Researchers linked the majority of the difference to overestimates of the “electric driving share” – the percentage of miles driven in electric power relative to overall distance. The team found that only 27% of travel was completed in electric mode, whereas official estimates assumed 84%.

Even, when running in EV mode, pollution levels were well above lab projections. This occurred because electric motors were not strong enough to function independently, leading to combustion motors burning fossil fuels for almost a third of the travel covered in EV mode.

Policy and Economic Consequences

According to calculations, the underestimation of PHEV CO2 output enabled several large carmaker companies to escape more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 extra per year in running expenses than is assumed under lab conditions.

“The bold statements that automakers often promote about their PHEV cars are obviously far from the mark,” stated a transport analyst. “Buyers are being misled into thinking that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are little better than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have lately been drawn again into policy discussions as carmakers have lobbied the European Union to relax CO₂ targets. A planned ban on new internal combustion vehicles in 2035 has faced intense lobbying from the car industry and resistance from member states with significant car industries.

Several high-level politicians have proposed PHEVs as a potential “compromise” option to include in the legislation.

An independent energy economics expert, who was not involved with the study, described the analysis a “very useful addition” after a long period in which segments of the car industry claimed there was too little information to accurately assess actual CO2 output.

“These findings show, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ output is significantly greater than for gasoline or diesel vehicles,” they said. “Any regulatory adjustments regarding PHEVs should be implemented with extreme caution and in the light of that data.”