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PHEVs release almost five times more planet-heating emissions than lab-reported data show, as per a new report.

Widening Discrepancy Between Lab and Actual CO2 Output

Statistics reveals that PHEVs release just 19% less CO₂ than conventional petrol and diesel cars, according to research conducted by a advocacy organization. This differs sharply with laboratory tests, which suggested a three-quarters decrease in pollution.

Researchers examined data from in-vehicle fuel consumption meters of 800,000 vehicles sold in Europe between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” stated a lead researcher involved in the report. “That discrepancy is growing and creates a serious issue. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the ratio of miles driven in battery mode relative to overall mileage. They found that only 27% of travel was done in EV mode, whereas official estimates assumed 84%.

Additionally, when running in EV mode, pollution amounts were well above official projections. This happened because EV motors were insufficiently powerful enough to operate alone, leading to engines burning fossil fuels for almost a third of the travel covered in EV mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV CO2 output allowed four major automaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 extra per year in running expenses than is estimated under laboratory conditions.

“The strong statements that automakers often promote about their plug-in hybrid cars are clearly way off the truth,” stated a transport analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are little improved than standard petrol and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been brought back into political discussions as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion cars in 2035 has faced heavy pressure from the car industry and opposition from member states with large car industries.

Several senior politicians have suggested plug-in hybrids as a potential “compromise” solution to include in the regulation.

An independent energy policy specialist, who was unaffiliated with the study, called the report a “very useful contribution” after a long period in which segments of the automotive sector argued there was too little data to properly assess actual emissions.

“The results demonstrate, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or diesel cars,” they stated. “All policy adjustments concerning PHEVs should be made with utmost caution and considering that data.”