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Plug-in hybrid cars produce nearly five times more planet-heating pollution than lab-reported figures show, according to a recent analysis.

Growing Discrepancy Between Lab and Real-World Emissions

Statistics reveals that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to analysis carried out by a advocacy group. That differs significantly with laboratory tests, which assumed a 75% reduction in pollution.

Researchers examined data from onboard energy use monitors of eight hundred thousand cars registered in Europe between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” stated a lead researcher participating in the report. “That gap is widening and creates a significant problem. Consequently, PHEVs emit nearly as heavily as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Researchers linked most of the difference to overestimates of the “utility factor” – the ratio of miles driven in electric power compared to overall distance. They found that just 27% of travel was completed in EV mode, while lab assumptions suggested over four-fifths.

Additionally, when running in EV mode, pollution amounts were significantly higher than official estimates. This happened because electric motors were not strong enough to operate independently, resulting to combustion motors burning gasoline for nearly a third of the distance covered in electric mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV CO2 output allowed several major carmaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 more per year in operating expenses than is assumed under lab conditions.

“The bold statements that manufacturers like to make about their PHEV cars are obviously way off the mark,” commented a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly better than standard petrol and diesel cars in terms of energy use, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Lobbying

Hybrid cars have lately been brought again into policy debates as carmakers have lobbied the European Union to relax CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and resistance from member states with significant automotive industries.

Several senior politicians have suggested PHEVs as a possible “flexibility” option to introduce in the regulation.

An external energy economics specialist, who was not involved with the research, described the analysis a “very useful addition” after years in which segments of the car sector claimed there was too little information to accurately evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional cars,” the expert stated. “All policy adjustments concerning PHEVs should be made with extreme care and considering this evidence.”