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Plug-in hybrid cars emit nearly five times greater planet-heating pollution than official data indicate, according to a recent analysis.

Widening Discrepancy In Lab and Actual CO2 Output

Data shows that PHEVs release just 19% lower CO₂ than traditional petrol and diesel vehicles, according to research carried out by a advocacy organization. This differs sharply with laboratory estimates, which assumed a 75% reduction in emissions.

Analysts examined data from in-vehicle energy use monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” stated a senior researcher participating in the report. “This discrepancy is widening and poses a significant problem. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Researchers linked most of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in electric power relative to overall mileage. The team determined that just 27% of travel was done in electric mode, whereas lab assumptions assumed 84%.

Additionally, when operating in EV mode, pollution amounts were significantly higher than lab estimates. This occurred because EV motors were not strong enough to operate independently, leading to engines using fossil fuels for nearly a third of the distance covered in electric mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV emissions enabled four major automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could pay about €500 extra per year in operating expenses than is estimated under lab conditions.

“The bold claims that automakers often promote about their PHEV cars are obviously way off the mark,” stated a transport analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Political Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been drawn back into policy discussions as carmakers have pressed the European Union to relax CO₂ targets. A planned prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and opposition from member states with significant automotive manufacturing.

Some senior officials have suggested plug-in hybrids as a possible “flexibility” solution to include in the regulation.

One independent energy economics expert, who was unaffiliated with the study, called the report a “very useful contribution” after a long period in which parts of the car sector claimed there was insufficient information to properly evaluate actual emissions.

“These findings 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 considering this data.”