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Plug-in hybrid cars produce almost 5x greater planet-heating emissions than official data show, according to a recent analysis.

Growing Discrepancy In Lab and Real-World Emissions

Data shows that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel cars, according to analysis conducted by a non-profit organization. That contrasts sharply with lab tests, which assumed a three-quarters decrease in pollution.

Analysts examined information from in-vehicle energy use meters of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while official emissions are decreasing,” said a lead analyst participating in the study. “This discrepancy is widening and poses a significant issue. Consequently, PHEVs emit nearly as heavily as gasoline cars.”

Key Factors Driving the Emissions Gap

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers driven in electric mode relative to overall mileage. The team determined that only 27% of travel was completed in EV mode, while official estimates assumed 84%.

Additionally, when operating in electric mode, emission amounts were well above official projections. That occurred because electric motors were insufficiently powerful sufficient to operate independently, resulting to engines using gasoline for nearly a third of the travel covered in electric mode.

Regulatory and Financial Consequences

According to estimates, the lowballing of PHEV CO2 output enabled several large automaker companies to escape over €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs could spend approximately €500 more annually in running expenses than is estimated under lab tests.

“The strong claims that manufacturers often promote about their PHEV vehicles are obviously far from the mark,” commented a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ production, and operating costs.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn again into political discussions as automakers have pressed the European Union to relax CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced intense lobbying from the automotive industry and resistance from member states with significant automotive manufacturing.

Several high-level politicians have proposed plug-in hybrids as a potential “compromise” option to include in the regulation.

One external energy economics expert, who was unaffiliated with the research, called the analysis a “highly valuable addition” after years in which parts of the automotive industry argued there was too little information to properly assess actual emissions.

“The results show, beyond any doubt, that the gap between lab and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert stated. “All regulatory adjustments concerning PHEVs should be made with extreme caution and in the light of that data.”