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Plug-in hybrid cars emit nearly 5x greater global warming emissions than lab-reported data show, according to a recent report.

Growing Discrepancy In Official and Real-World CO2 Output

Statistics shows that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel cars, based on analysis conducted by a non-profit organization. That contrasts significantly with lab tests, which assumed a 75% decrease in emissions.

Researchers studied information from onboard fuel consumption monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while official figures are decreasing,” stated a senior analyst participating in the report. “That discrepancy is widening and creates a significant issue. As a result, PHEVs pollute almost as much as gasoline cars.”

Key Factors Driving the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric power relative to overall mileage. The team found that only a quarter of driving was completed in EV mode, while official assumptions assumed over four-fifths.

Even, when running in electric mode, pollution levels were significantly higher than official projections. This occurred because EV motors were not strong sufficient to function independently, leading to combustion motors using gasoline for almost one-third of the travel completed in EV mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV CO2 output enabled four large carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs would spend about €500 more per year in operating expenses than would be estimated under laboratory conditions.

“The bold claims that automakers often promote about their plug-in hybrid vehicles are obviously way off the truth,” stated a automotive analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little improved than standard gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have lately been brought again into policy debates as automakers have pressed the EU to relax CO₂ standards. A planned prohibition on new internal combustion cars in 2035 has faced heavy lobbying from the car industry and opposition from member states with large car manufacturing.

Some high-level officials have proposed PHEVs as a potential “compromise” option to introduce in the regulation.

One independent energy economics expert, who was not involved with the research, called the report a “very useful addition” after years in which parts of the car industry argued there was too little data to properly evaluate real-world emissions.

“The results show, without question, that the gap in official and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or diesel cars,” the expert stated. “Any policy changes concerning PHEVs should be made with extreme care and in the light of this evidence.”