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PHEVs release almost five times more global warming pollution than official figures indicate, as per a recent analysis.

Growing Gap In Official and Real-World CO2 Output

Data reveals that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, based on research carried out by a non-profit group. That differs significantly with laboratory tests, which assumed a 75% reduction in emissions.

Researchers studied data from onboard energy use meters of 800,000 cars registered in Europe from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” stated a senior researcher involved in the report. “This discrepancy is widening and creates a serious problem. As a result, PHEVs emit almost as much as petrol cars.”

Key Factors Behind the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric mode relative to total mileage. They determined that only 27% of driving was done in EV mode, whereas lab assumptions suggested 84%.

Additionally, when running in electric mode, emission amounts were well above lab projections. This occurred because EV motors were insufficiently powerful enough to function alone, leading to engines burning fossil fuels for almost one-third of the travel completed in EV mode.

Regulatory and Economic Implications

According to estimates, the underestimation of PHEV emissions enabled four major automaker groups to avoid over €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 extra annually in running costs than would be estimated under lab tests.

“The bold claims that manufacturers like to make about their PHEV cars are clearly far from the mark,” stated a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have lately been drawn back into political discussions as automakers have lobbied the EU to weaken CO₂ targets. A proposed ban on new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from EU countries with significant automotive industries.

Several high-level politicians have proposed PHEVs as a possible “flexibility” solution to include in the regulation.

An independent energy economics expert, who was not involved with the study, called the report a “very useful contribution” after a long period in which segments of the car industry argued there was too little information to properly evaluate real-world CO2 output.

“The results show, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is much, much greater than for petrol or diesel cars,” the expert stated. “Any regulatory adjustments concerning PHEVs should be implemented with utmost caution and considering that evidence.”