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Plug-in hybrid cars release almost five times greater global warming emissions than lab-reported data show, as per a recent report.

Growing Discrepancy Between Lab and Actual CO2 Output

Statistics shows that PHEVs emit just one-fifth less CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a advocacy group. That differs sharply with lab estimates, which suggested a 75% decrease in pollution.

Analysts studied data from onboard fuel consumption meters of 800,000 vehicles registered in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” stated a senior researcher involved in the report. “That gap is widening and creates a significant issue. As a result, PHEVs emit nearly as much as gasoline cars.”

Primary Reasons Behind the Discrepancy

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

Even, when operating in electric mode, emission levels were well above lab estimates. That happened because EV motors were not strong enough to function independently, resulting to engines burning fossil fuels for nearly one-third of the travel completed in EV mode.

Regulatory and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output allowed four major automaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 more per year in operating expenses than is assumed under lab tests.

“The strong statements that automakers like to make about their plug-in hybrid cars are clearly far from the mark,” commented a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running costs.”

Political Discussion and Industry Pressure

Hybrid vehicles have lately been brought back into policy discussions as carmakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and opposition from EU countries with large automotive manufacturing.

Some senior politicians have suggested plug-in hybrids as a possible “flexibility” solution to introduce in the legislation.

An independent energy economics specialist, who was unaffiliated with the research, called the report a “very useful addition” after a long period in which segments of the automotive sector argued there was insufficient data to accurately evaluate actual CO2 output.

“The results show, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or conventional cars,” the expert stated. “All policy adjustments regarding PHEVs should be made with extreme care and in the light of this evidence.”