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PHEVs emit almost 5x greater global warming emissions than lab-reported data show, as per a new analysis.

Growing Discrepancy Between Lab and Actual CO2 Output

Data reveals that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel cars, according to research carried out by a non-profit organization. That differs sharply with lab estimates, which suggested a three-quarters reduction in emissions.

Analysts studied data from in-vehicle fuel consumption monitors of 800,000 cars registered in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported emissions are falling,” said a lead analyst involved in the report. “That discrepancy is widening and poses a serious problem. As a result, PHEVs pollute nearly as much as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Researchers linked most of the gap to inflated estimates of the “utility factor” – the percentage of miles driven in battery power compared to overall mileage. They found that just 27% of driving was done in EV mode, whereas lab estimates assumed 84%.

Even, when running in EV mode, pollution levels were significantly higher than official projections. That occurred because EV motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors burning gasoline for nearly one-third of the travel covered in electric mode.

Policy and Economic Consequences

According to calculations, the underestimation of PHEV emissions allowed several large automaker companies to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more per year in running costs than is estimated under lab conditions.

“The strong claims that manufacturers like to make about their plug-in hybrid vehicles are obviously way off the truth,” commented a automotive analyst. “Consumers are being misled into believing that by buying a PHEV, they are helping the environment and saving costs. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Policy Discussion and Automotive Pressure

Hybrid cars have recently been brought back into political discussions as carmakers have pressed the EU to relax CO₂ standards. A planned ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the car sector and resistance from member states with significant automotive industries.

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

One independent energy policy expert, who was unaffiliated with the research, described the report a “very useful addition” after years in which parts of the car industry argued there was insufficient information to properly evaluate real-world emissions.

“The results show, beyond any doubt, that the difference between lab and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel cars,” the expert said. “Any regulatory adjustments regarding PHEVs should be made with utmost caution and in the light of this data.”