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PHEVs emit almost 5x greater global warming emissions than lab-reported figures indicate, as per a new report.

Growing Gap Between Lab and Real-World Emissions

Data reveals that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on analysis conducted by a advocacy group. This contrasts sharply with lab estimates, which assumed a three-quarters reduction in emissions.

Researchers examined information from in-vehicle energy use monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” stated a senior researcher participating in the study. “That discrepancy is widening and creates a significant problem. As a result, PHEVs emit nearly as much as petrol cars.”

Primary Factors Behind the Emissions Gap

Analysts attributed most of the difference to overestimates of the “utility factor” – the ratio of miles travelled in electric power compared to overall mileage. They found that only a quarter of driving was done in electric mode, while lab estimates assumed 84%.

Even, when running in EV mode, pollution amounts were significantly higher than lab projections. That happened because electric motors were not strong enough to operate alone, resulting to combustion motors burning fossil fuels for almost one-third of the distance covered in EV mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV CO2 output allowed several major automaker companies to avoid more than €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay approximately €500 more per year in operating expenses than is assumed under lab tests.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are clearly way off the mark,” commented a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Political Discussion and Automotive Lobbying

Hybrid cars have recently been brought back into political debates as automakers have pressed the EU to weaken CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the car industry and resistance from member states with large automotive manufacturing.

Some high-level officials have proposed PHEVs as a potential “compromise” solution to include in the legislation.

One independent energy policy specialist, who was not involved with the study, called the report a “highly valuable addition” after years in which segments of the automotive industry argued there was too little data to accurately assess real-world emissions.

“The results show, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or conventional vehicles,” they said. “Any regulatory adjustments regarding PHEVs should be implemented with extreme caution and considering that evidence.”