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Plug-in hybrid cars emit almost 5x more planet-heating emissions than official data indicate, as per a recent report.

Growing Discrepancy In Lab and Actual Emissions

Data shows that PHEVs release just one-fifth less CO₂ than traditional gas and diesel cars, based on research carried out by a advocacy group. This contrasts significantly with laboratory tests, which suggested a three-quarters reduction in pollution.

Researchers examined information from onboard fuel consumption monitors of eight hundred thousand vehicles registered in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are falling,” stated a lead researcher participating in the study. “That discrepancy is growing and poses a serious problem. Consequently, PHEVs emit nearly as much as petrol cars.”

Primary Factors Driving the Emissions Gap

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in battery power relative to total distance. The team found that just a quarter of driving was completed in EV mode, whereas lab estimates suggested over four-fifths.

Even, when running in EV mode, pollution amounts were well above lab projections. That occurred because EV motors were not strong sufficient to function alone, resulting to combustion motors burning fossil fuels for nearly one-third of the travel covered in EV mode.

Policy and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output enabled four large automaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs could pay approximately €500 more per year in running costs than would be assumed under lab conditions.

“The strong statements that manufacturers like to make about their PHEV cars are obviously far from the truth,” stated a transport analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting money. Actually, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Political Debate and Industry Pressure

Hybrid cars have recently been drawn again into policy debates as carmakers have pressed the EU to relax CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with large car industries.

Some senior politicians have proposed plug-in hybrids as a potential “compromise” option to introduce in the regulation.

An independent energy economics specialist, who was unaffiliated with the study, described the report a “very useful addition” after years in which segments of the automotive sector claimed there was too little data to accurately evaluate real-world emissions.

“These findings demonstrate, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or conventional vehicles,” the expert stated. “Any regulatory adjustments regarding PHEVs should be implemented with utmost care and in the light of that data.”