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Plug-in hybrid electric vehicles produce nearly 5x greater global warming pollution than official figures show, as per a recent report.

Growing Gap Between Lab and Real-World Emissions

Data shows that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, according to research conducted by a advocacy organization. That differs significantly with lab estimates, which assumed a three-quarters decrease in pollution.

Analysts studied information from in-vehicle fuel consumption meters of eight hundred thousand vehicles registered in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” stated a lead analyst participating in the study. “That discrepancy is widening and creates a serious problem. As a result, PHEVs pollute nearly as much as gasoline cars.”

Primary Factors Behind the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in electric power relative to total distance. The team found that just 27% of driving was done in EV mode, while lab estimates assumed 84%.

Even, when operating in electric mode, emission amounts were significantly higher than official projections. That happened because electric motors were not strong enough to function alone, resulting to combustion motors using fossil fuels for nearly a third of the travel covered in EV mode.

Policy and Financial Implications

According to estimates, the underestimation of PHEV emissions enabled several major carmaker groups to avoid over €5bn in fines between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 extra per year in running costs than would be estimated under laboratory tests.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are obviously far from the mark,” stated a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Debate and Industry Pressure

Hybrid vehicles have recently been brought again into political debates as carmakers have pressed the EU to relax CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy lobbying from the car industry and resistance from member states with significant automotive manufacturing.

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

One external energy economics expert, who was not involved with the research, described the report a “very useful addition” after a long period in which segments of the automotive sector claimed there was too little data to properly evaluate actual emissions.

“The results show, without question, that the gap between lab and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” the expert stated. “Any policy changes regarding PHEVs should be implemented with extreme care and considering that evidence.”