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Plug-in hybrid electric vehicles produce nearly 5x greater planet-heating emissions than lab-reported data indicate, according to a recent analysis.

Widening Discrepancy In Lab and Real-World CO2 Output

Statistics shows that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a advocacy group. That differs sharply with laboratory estimates, which suggested a 75% decrease in pollution.

Researchers studied information from in-vehicle energy use monitors of eight hundred thousand cars sold in Europe from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while official emissions are decreasing,” said a senior analyst participating in the study. “That gap is growing and poses a significant problem. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Key Factors Behind the Emissions Gap

Analysts attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in battery power relative to overall mileage. They found that only 27% of driving was done in electric mode, whereas lab estimates suggested over four-fifths.

Even, when operating in EV mode, emission levels were significantly higher than official estimates. That occurred because electric motors were not strong sufficient to operate alone, resulting to engines burning fossil fuels for almost a third of the distance covered in EV mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV emissions enabled four major carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would pay about €500 extra per year in operating expenses than is assumed under laboratory tests.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are obviously way off the truth,” commented a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little better than regular gas and diesel cars in terms of energy use, CO₂ production, and running costs.”

Political Discussion and Industry Pressure

Hybrid vehicles have recently been drawn back into policy debates 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 automotive industry and resistance from member states with significant car industries.

Some high-level politicians have suggested PHEVs as a possible “flexibility” option to include in the legislation.

One independent energy economics expert, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after years in which parts of the automotive industry claimed there was too little information to accurately evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or conventional cars,” they said. “Any policy changes regarding PHEVs should be implemented with extreme care and in the light of that evidence.”