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PHEVs emit nearly five times more global warming emissions than official figures show, as per a new analysis.

Growing Discrepancy In Lab and Real-World CO2 Output

Data reveals that PHEVs release only one-fifth less CO₂ than traditional gas and diesel vehicles, according to research carried out by a non-profit group. This contrasts significantly with lab estimates, which assumed a 75% decrease in pollution.

Researchers studied data from in-vehicle fuel consumption monitors of eight hundred thousand vehicles registered 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 lab figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported figures are falling,” said a senior researcher involved in the report. “That discrepancy is growing and creates a serious issue. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Factors Behind the Discrepancy

Analysts linked most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery mode compared to total distance. They found that just 27% of driving was completed in electric mode, whereas lab estimates assumed over four-fifths.

Even, when running in electric mode, pollution amounts were well above lab estimates. This occurred because electric motors were insufficiently powerful sufficient to operate alone, resulting to combustion motors using gasoline for almost a third of the distance completed in EV mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV emissions enabled four major carmaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could spend approximately €500 extra annually in operating expenses than would be estimated under laboratory tests.

“The strong claims that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” stated a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Policy Discussion and Industry Pressure

Plug-in hybrid vehicles have recently been drawn back into political debates as carmakers have pressed the EU to relax CO₂ standards. A planned prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the car industry and opposition from member states with large automotive industries.

Several senior officials have suggested plug-in hybrids as a potential “flexibility” solution to include in the legislation.

One independent energy economics expert, who was unaffiliated with the research, described the report a “highly valuable contribution” after a long period in which parts of the automotive industry claimed there was too little information to accurately evaluate actual emissions.

“These findings demonstrate, without question, that the difference in official and actual PHEV energy use and CO₂ output is significantly larger than for gasoline or diesel cars,” they said. “All regulatory adjustments regarding PHEVs should be implemented with utmost caution and considering this data.”