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Plug-in hybrid cars emit almost 5x greater planet-heating pollution than official data show, as per a recent analysis.

Widening Discrepancy In Lab and Actual Emissions

Statistics shows that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel cars, based on research conducted by a non-profit organization. This differs sharply with laboratory tests, which assumed a 75% decrease in pollution.

Analysts studied data from onboard energy use monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Real-world emissions are increasing, while official emissions are decreasing,” said a lead researcher involved in the study. “This gap is widening and creates a significant problem. As a result, PHEVs emit nearly as much as petrol cars.”

Key Reasons Behind the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the ratio of miles travelled in battery mode relative to overall mileage. The team found that just 27% of travel was completed in electric mode, whereas lab assumptions suggested 84%.

Even, when operating in electric mode, emission amounts were significantly higher than official estimates. This happened because electric motors were not strong sufficient to operate independently, resulting to engines burning gasoline for nearly a third of the travel covered in electric mode.

Regulatory and Financial Implications

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

Furthermore, owners of PHEVs would pay about €500 more annually in operating expenses than is assumed under laboratory tests.

“The bold statements that manufacturers often promote about their PHEV vehicles are clearly way off the truth,” stated a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Lobbying

Hybrid vehicles have recently been brought again into policy debates as carmakers have lobbied the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and resistance from EU countries with large automotive manufacturing.

Several high-level politicians have proposed plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

One independent energy economics expert, who was unaffiliated with the research, called the analysis a “very useful contribution” after years in which parts of the car industry claimed there was too little data to properly evaluate actual CO2 output.

“The results show, without question, that the gap in official and real-world PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional vehicles,” the expert stated. “All policy changes concerning PHEVs should be implemented with extreme caution and in the light of this data.”