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PHEVs emit almost five times more planet-heating emissions than lab-reported figures indicate, as per a new analysis.

Growing Gap In Official and Actual CO2 Output

Statistics shows that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a non-profit group. That contrasts sharply with lab estimates, which assumed a 75% decrease in pollution.

Analysts examined information from in-vehicle energy use monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from 3.5 times in 2021.

“Actual emissions are increasing, while official figures are falling,” said a lead researcher participating in the study. “This discrepancy is widening and poses a serious problem. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Key Factors Driving the Discrepancy

Researchers linked most of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in battery mode compared to overall distance. They found that only 27% of travel was done in EV mode, whereas official assumptions assumed 84%.

Additionally, when running in electric mode, emission levels were well above official estimates. That happened because EV motors were not strong sufficient to operate alone, resulting to engines using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output enabled several major automaker companies to escape over €5bn in fines between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 more annually in running expenses than is estimated under lab conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are obviously far from the mark,” stated a transport expert. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn back into policy debates as automakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and opposition from EU countries with significant automotive manufacturing.

Some senior officials have suggested PHEVs as a possible “compromise” option to introduce in the regulation.

An independent energy policy expert, who was unaffiliated with the study, described the analysis a “very useful contribution” after years in which segments of the automotive industry claimed there was insufficient data to accurately assess real-world emissions.

“These findings show, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or conventional vehicles,” they said. “All regulatory changes concerning PHEVs should be implemented with extreme care and considering that evidence.”