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Plug-in hybrid electric vehicles produce nearly 5x greater planet-heating pollution than lab-reported data indicate, according to a new analysis.

Widening Discrepancy In Lab and Real-World CO2 Output

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel cars, based on research carried out by a non-profit group. This contrasts sharply with lab estimates, which assumed a three-quarters reduction in emissions.

Researchers studied data from in-vehicle fuel consumption meters of 800,000 cars sold in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” stated a senior researcher participating in the study. “This discrepancy is growing and creates a serious issue. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Key Factors Behind the Discrepancy

Analysts attributed the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to overall mileage. The team found that just a quarter of driving was done in electric mode, whereas official estimates assumed over four-fifths.

Even, when operating in EV mode, pollution levels were significantly higher than lab projections. This happened because electric motors were not strong enough to function independently, resulting to combustion motors using fossil fuels for nearly one-third of the travel completed in electric mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV CO2 output enabled four major carmaker groups to escape over €5bn in fines between 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 more annually in operating expenses than is estimated under laboratory conditions.

“The bold statements that manufacturers like to make about their PHEV vehicles are obviously way off the mark,” commented a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Political Debate and Automotive Lobbying

Hybrid vehicles have recently been brought again into political discussions as automakers have pressed the European Union to relax CO₂ targets. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and opposition from EU countries with significant automotive industries.

Some senior politicians have suggested PHEVs as a potential “flexibility” option to introduce in the regulation.

One independent energy policy specialist, who was unaffiliated with the study, called the analysis a “highly valuable addition” after a long period in which segments of the car sector claimed there was insufficient information to properly evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the gap in official and actual PHEV energy use and CO₂ output is significantly greater than for gasoline or conventional cars,” the expert stated. “All regulatory adjustments concerning PHEVs should be made with utmost care and considering this data.”