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Plug-in hybrid electric vehicles emit nearly five times greater global warming emissions than official figures show, according to a recent report.

Widening Discrepancy In Lab and Real-World CO2 Output

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel vehicles, based on research conducted by a non-profit organization. That contrasts sharply with laboratory tests, which suggested a three-quarters decrease in pollution.

Analysts examined data from onboard fuel consumption monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are decreasing,” said a senior researcher participating in the study. “That gap is growing and poses a serious issue. As a result, PHEVs pollute almost as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Researchers linked the majority of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in battery power relative to total distance. They determined that only 27% of driving was completed in EV mode, whereas official assumptions assumed 84%.

Even, when operating in EV mode, pollution levels were well above official projections. That occurred because EV motors were not strong enough to operate alone, leading to engines burning fossil fuels for almost a third of the distance covered in EV mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed several large carmaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 extra annually in running expenses than would be estimated under lab conditions.

“The bold claims that manufacturers like to make about their PHEV vehicles are clearly far from the mark,” commented a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running expenses.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been brought back into political discussions as carmakers have pressed the EU to weaken CO₂ standards. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the automotive industry and opposition from member states with significant car industries.

Some high-level officials have proposed plug-in hybrids as a possible “flexibility” option to introduce in the legislation.

One external energy policy expert, who was not involved with the research, called the report a “highly valuable addition” after years in which parts of the car sector argued there was insufficient information to properly assess real-world CO2 output.

“These findings show, without question, that the gap between lab and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or diesel cars,” they stated. “All policy changes regarding PHEVs should be implemented with extreme care and considering that evidence.”