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Plug-in hybrid electric vehicles emit nearly five times greater global warming emissions than official data indicate, according to a new analysis.

Growing Discrepancy In Lab and Real-World Emissions

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel vehicles, according to analysis carried out by a advocacy organization. That contrasts significantly with laboratory estimates, which suggested a 75% decrease in pollution.

Analysts studied information from onboard energy use monitors of eight hundred thousand cars sold in the EU from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are falling,” stated a senior analyst participating in the study. “That gap is widening and creates a significant problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Primary Factors Behind the Discrepancy

Analysts linked the majority of the difference to overestimates of the “utility factor” – the ratio of miles travelled in electric mode compared to overall distance. The team found that only a quarter of travel was completed in EV mode, whereas official estimates assumed 84%.

Additionally, when running in electric mode, emission levels were well above lab estimates. This occurred because electric motors were not strong enough to operate alone, resulting to engines burning fossil fuels for nearly a third of the travel completed in EV mode.

Policy and Economic Implications

According to calculations, the lowballing of PHEV emissions enabled several large carmaker groups to avoid more than €5bn in fines between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend approximately €500 more annually in operating costs than is assumed under laboratory tests.

“The strong claims that manufacturers like to make about their plug-in hybrid cars are obviously way off the truth,” commented a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little better than regular gas and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Political Discussion and Automotive Pressure

Plug-in hybrid vehicles have recently been brought again into political discussions as carmakers have lobbied the European Union to relax CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced intense lobbying from the automotive sector and opposition from member states with large car industries.

Several senior officials have proposed PHEVs as a potential “flexibility” solution to include in the legislation.

An external energy policy expert, who was unaffiliated with the research, called the report a “highly valuable addition” after a long period in which parts of the car sector claimed there was too little information to properly evaluate actual CO2 output.

“The results demonstrate, without question, that the gap in lab and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel vehicles,” the expert said. “All regulatory changes regarding PHEVs should be implemented with utmost caution and considering this evidence.”