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Plug-in hybrid electric vehicles release almost 5x more planet-heating emissions than official data show, as per a new analysis.

Growing Discrepancy Between Lab and Real-World Emissions

Statistics reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a non-profit group. That differs significantly with lab tests, which assumed a three-quarters reduction in pollution.

Analysts examined data from onboard fuel consumption meters of 800,000 vehicles registered in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, increased from three and a half times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” stated a lead researcher participating in the study. “This gap is widening and poses a serious problem. As a result, PHEVs emit almost as much as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers linked most of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric power relative to total distance. They found that only 27% of driving was completed in EV mode, whereas official estimates suggested 84%.

Additionally, when running in EV mode, pollution amounts were well above lab estimates. That occurred because electric motors were not strong sufficient to operate alone, leading to engines using fossil fuels for almost a third of the distance covered in electric mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV emissions allowed four large carmaker companies to escape more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay approximately €500 extra per year in operating expenses than would be estimated under laboratory tests.

“The strong statements that manufacturers like to make about their PHEV vehicles are obviously far from the truth,” commented a transport expert. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating expenses.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn again into political debates as carmakers have pressed the European Union to weaken CO₂ targets. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and resistance from member states with large automotive manufacturing.

Several senior politicians have proposed PHEVs as a potential “flexibility” solution to include in the regulation.

One independent energy policy expert, who was unaffiliated with the research, called the report a “very useful addition” after years in which parts of the automotive sector claimed there was too little data to properly assess actual emissions.

“These findings show, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel vehicles,” they stated. “Any regulatory adjustments concerning PHEVs should be implemented with utmost care and considering that evidence.”