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PHEVs produce almost five times more planet-heating emissions than official data show, according to a new report.

Widening Gap In Official and Real-World Emissions

Data reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, according to research conducted by a non-profit organization. This differs sharply with laboratory estimates, which suggested a three-quarters reduction in pollution.

Analysts examined data from in-vehicle fuel consumption monitors of 800,000 cars sold in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” said a senior researcher participating in the report. “This gap is growing and creates a serious issue. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Analysts attributed most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in battery mode relative to overall mileage. They found that only 27% of travel was completed in EV mode, while lab estimates assumed 84%.

Additionally, when running in EV mode, pollution levels were well above official projections. That occurred because electric motors were insufficiently powerful sufficient to function independently, leading to engines using gasoline for nearly one-third of the travel completed in electric mode.

Regulatory and Financial Implications

According to calculations, the lowballing of PHEV emissions allowed four large automaker groups to escape over €5bn in fines between 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ standards.

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

“The bold statements that manufacturers like to make about their plug-in hybrid cars are obviously far from the mark,” stated a automotive expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Political Debate and Industry Lobbying

Plug-in hybrid cars have recently been drawn back into political discussions as carmakers have pressed the European Union to relax CO₂ standards. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the car sector and resistance from EU countries with significant car manufacturing.

Several senior officials have proposed PHEVs as a possible “compromise” solution to include in the regulation.

An independent energy policy expert, who was unaffiliated with the research, described the analysis a “very useful addition” after a long period in which segments of the automotive sector argued there was too little data to properly evaluate actual CO2 output.

“The results show, without question, that the gap between lab and actual PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel cars,” they said. “All regulatory adjustments regarding PHEVs should be made with utmost care and considering this evidence.”