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PHEVs emit nearly 5x more planet-heating pollution than official data show, according to a new report.

Widening Discrepancy In Official and Real-World Emissions

Statistics shows that PHEVs release just 19% lower CO₂ than traditional petrol and diesel vehicles, based on analysis conducted by a advocacy organization. That contrasts sharply with lab tests, which assumed a 75% decrease in pollution.

Analysts examined data from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in the EU between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported figures are decreasing,” said a senior researcher involved in the study. “This gap is widening and poses a significant issue. Consequently, PHEVs pollute nearly as much as gasoline vehicles.”

Key Reasons Behind the Emissions Gap

Analysts linked most of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric power relative to total mileage. The team determined that just 27% of driving was done in electric mode, while lab estimates suggested over four-fifths.

Even, when operating in electric mode, emission amounts were well above lab projections. This happened because EV motors were insufficiently powerful enough to function independently, resulting to combustion motors burning gasoline for nearly one-third of the travel completed in EV mode.

Policy and Economic Implications

According to calculations, the lowballing of PHEV CO2 output allowed several major carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ standards.

Additionally, owners of PHEVs could pay about €500 extra annually in running costs than would be assumed under lab conditions.

“The bold statements that automakers like to make about their PHEV cars are obviously far from the truth,” commented a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little improved than regular gas and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been brought back into policy discussions as carmakers have lobbied the EU to relax CO₂ targets. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with significant automotive industries.

Some high-level politicians have suggested plug-in hybrids as a potential “flexibility” solution to introduce in the legislation.

One independent energy economics specialist, who was unaffiliated with the study, described the report a “very useful contribution” after years in which segments of the car industry argued there was too little information to properly assess real-world CO2 output.

“The results show, beyond any doubt, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional vehicles,” the expert stated. “Any policy adjustments regarding PHEVs should be made with utmost caution and in the light of this data.”