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PHEVs produce almost 5x more planet-heating pollution than official data indicate, as per a recent analysis.

Growing Discrepancy Between Lab and Actual Emissions

Statistics reveals that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel cars, based on research carried out by a advocacy organization. That contrasts significantly with laboratory estimates, which assumed a three-quarters decrease in pollution.

Analysts examined data from in-vehicle energy use monitors of 800,000 cars registered in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” said a senior researcher involved in the report. “That discrepancy is widening and poses a serious problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Primary Reasons Behind the Emissions Gap

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric mode compared to overall distance. The team determined that just 27% of driving was done in electric mode, while lab estimates assumed 84%.

Additionally, when operating in EV mode, emission amounts were well above lab estimates. This happened because electric motors were not strong sufficient to operate independently, resulting to combustion motors using fossil fuels for nearly a third of the distance completed in electric mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV emissions enabled four large carmaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs could pay about €500 extra annually in operating costs than is estimated under lab tests.

“The strong claims that manufacturers like to make about their plug-in hybrid vehicles are obviously way off the mark,” commented a transport expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are little better than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Pressure

Hybrid cars have lately been drawn back into policy debates as carmakers have lobbied the EU to relax CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy lobbying from the automotive industry and resistance from member states with significant automotive industries.

Some senior politicians have proposed PHEVs as a possible “compromise” solution to include in the legislation.

One independent energy economics specialist, who was unaffiliated with the study, called the report a “highly valuable contribution” after a long period in which parts of the car industry claimed there was too little data to properly evaluate real-world CO2 output.

“These findings show, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” the expert said. “Any regulatory adjustments concerning PHEVs should be implemented with utmost care and in the light of this data.”