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Plug-in hybrid electric vehicles emit nearly 5x more planet-heating pollution than official data show, according to a recent analysis.

Growing Gap In Official and Actual CO2 Output

Statistics shows that PHEVs release only one-fifth lower CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a advocacy organization. This contrasts sharply with lab estimates, which suggested a 75% decrease in emissions.

Researchers examined information from in-vehicle fuel consumption meters of 800,000 cars sold in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” said a senior analyst involved in the study. “That discrepancy is widening and creates a serious problem. Consequently, PHEVs emit nearly as heavily as gasoline cars.”

Key Reasons Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers driven in battery power relative to total distance. They determined that just 27% of travel was completed in EV mode, while official estimates suggested over four-fifths.

Additionally, when running in electric mode, pollution levels were well above lab projections. That happened because EV motors were not strong enough to function alone, leading to combustion motors burning gasoline for nearly a third of the travel completed in electric mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV CO2 output allowed four large carmaker groups to avoid more than €5bn in fines from 2021 and 2023, by falsely simplifying compliance with European Union 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 strong claims that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the mark,” stated a transport expert. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little better than standard petrol and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have lately been brought again into political debates as automakers have pressed the European Union to relax CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with significant automotive manufacturing.

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

An external energy economics specialist, who was unaffiliated with the study, called the analysis a “highly valuable addition” after a long period in which segments of the automotive sector claimed there was too little information to properly evaluate actual emissions.

“These findings show, without question, that the difference between official and actual PHEV energy use and CO₂ output is much, much larger than for petrol or diesel vehicles,” the expert stated. “Any regulatory adjustments regarding PHEVs should be made with utmost caution and in the light of that data.”