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PHEVs release almost five times more global warming pollution than lab-reported data indicate, as per a new report.

Widening Discrepancy Between Official and Real-World CO2 Output

Data reveals that PHEVs release just 19% less CO₂ than conventional petrol and diesel cars, based on analysis conducted by a advocacy group. This differs significantly with lab estimates, which assumed a 75% reduction in pollution.

Researchers examined data from onboard energy use meters of eight hundred thousand cars sold in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are decreasing,” said a senior analyst participating in the study. “This discrepancy is growing and creates a serious problem. Consequently, PHEVs pollute almost as much as petrol cars.”

Primary Factors Behind the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in battery mode relative to total mileage. The team found that just a quarter of driving was completed in EV mode, while lab assumptions suggested over four-fifths.

Even, when running in electric mode, emission amounts were well above official projections. This happened because electric motors were not strong enough to function alone, resulting to combustion motors burning gasoline for almost a third of the distance covered in EV mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV emissions allowed four large automaker companies to avoid more than €5bn in fines between 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would spend about €500 more annually in operating expenses than is estimated under laboratory tests.

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are clearly far from the mark,” commented a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Debate and Industry Pressure

Hybrid cars have lately been drawn back into policy discussions as automakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the car sector and resistance from member states with significant car manufacturing.

Some high-level officials have suggested plug-in hybrids as a possible “flexibility” option to introduce in the legislation.

An external energy economics specialist, who was unaffiliated with the research, called the analysis a “very useful contribution” after a long period in which parts of the car industry argued there was insufficient data to accurately assess actual CO2 output.

“These findings show, beyond any doubt, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or diesel vehicles,” the expert said. “Any policy adjustments regarding PHEVs should be made with extreme caution and considering this data.”