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Plug-in hybrid cars emit nearly five times more global warming pollution than official figures indicate, according to a recent report.

Widening Gap In Official and Actual CO2 Output

Data reveals that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel cars, according to research conducted by a non-profit organization. That contrasts significantly with lab estimates, which assumed a 75% reduction in emissions.

Analysts studied data from in-vehicle energy use monitors of 800,000 cars sold in Europe between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Actual emissions are increasing, while official figures are decreasing,” stated a senior researcher involved in the report. “That gap is growing and creates a serious problem. Consequently, PHEVs pollute almost as much as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts linked most of the gap to overestimates of the “utility factor” – the ratio of kilometers driven in electric power relative to overall mileage. The team determined that just a quarter of travel was done in EV mode, while lab estimates assumed over four-fifths.

Even, when operating in EV mode, emission amounts were well above official projections. That happened because electric motors were insufficiently powerful enough to function independently, leading to combustion motors using gasoline for nearly one-third of the distance completed in EV mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV emissions allowed several major automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could pay approximately €500 extra annually in running costs than would be estimated under laboratory tests.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are obviously far from the truth,” commented a automotive analyst. “Buyers are being misled into thinking that by buying a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have recently been drawn again into policy debates as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on new internal combustion vehicles in 2035 has faced intense lobbying from the car industry and opposition from EU countries with significant automotive manufacturing.

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

One external energy policy expert, who was unaffiliated with the study, called the report a “highly valuable addition” after years in which parts of the car sector argued there was insufficient information to properly evaluate real-world CO2 output.

“These findings demonstrate, without question, that the gap between lab and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or diesel vehicles,” the expert stated. “Any policy changes regarding PHEVs should be implemented with utmost care and in the light of that evidence.”