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Plug-in hybrid cars produce nearly five times greater planet-heating emissions than official data show, according to a recent report.

Growing Discrepancy Between Official and Real-World Emissions

Data shows that PHEVs emit just one-fifth less CO₂ than traditional gas and diesel cars, based on analysis carried out by a advocacy organization. That differs significantly with lab estimates, which assumed a 75% reduction in emissions.

Researchers studied information from onboard energy use monitors of eight hundred thousand cars sold in Europe from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” stated a senior researcher participating in the report. “This gap is growing and poses a serious problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Primary Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers driven in battery mode compared to overall distance. The team found that just a quarter of travel was completed in EV mode, while lab estimates assumed 84%.

Even, when running in electric mode, pollution amounts were significantly higher than lab projections. That happened because electric motors were not strong sufficient to function alone, resulting to combustion motors using gasoline for almost a third of the travel covered in electric mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV emissions allowed several major carmaker companies to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs could pay approximately €500 more annually in running costs than is estimated under laboratory tests.

“The bold claims that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the mark,” stated a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Political Discussion and Automotive Lobbying

Hybrid cars have lately been drawn again into political debates as carmakers have lobbied the European Union to relax CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with large automotive manufacturing.

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

An external energy policy specialist, who was not involved with the research, described the analysis a “highly valuable contribution” after a long period in which parts of the car industry claimed there was insufficient data to properly assess real-world emissions.

“The results show, without question, that the difference in lab and real-world PHEV fuel consumption and CO₂ output is much, much larger than for petrol or conventional vehicles,” the expert stated. “All regulatory adjustments regarding PHEVs should be implemented with extreme caution and in the light of that data.”