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Plug-in hybrid electric vehicles emit almost five times greater planet-heating pollution than official data indicate, according to a new analysis.

Growing Discrepancy In Official and Actual CO2 Output

Statistics reveals that PHEVs release only 19% lower CO₂ than conventional petrol and diesel vehicles, according to research carried out by a non-profit group. This differs significantly with lab tests, which suggested a three-quarters decrease in pollution.

Analysts examined data from onboard energy use monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from three and a half times in 2021.

“Actual emissions are rising, while official emissions are falling,” stated a lead analyst involved in the study. “That gap is widening and creates a significant problem. As a result, PHEVs pollute nearly as much as petrol cars.”

Key Factors Behind the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric power compared to overall distance. They determined that just 27% of travel was done in electric mode, while official assumptions assumed over four-fifths.

Even, when running in EV mode, pollution levels were well above lab estimates. That happened because electric motors were not strong enough to function independently, leading to engines using gasoline for nearly one-third of the travel completed in electric mode.

Regulatory and Economic Consequences

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

Additionally, drivers of PHEVs would pay about €500 more per year in operating expenses than would be estimated under laboratory conditions.

“The strong claims that automakers like to make about their PHEV cars are obviously way off the mark,” stated a automotive analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have lately been drawn back into political discussions as automakers have pressed the EU to weaken CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and resistance from EU countries with large automotive industries.

Some senior politicians have suggested PHEVs as a potential “compromise” solution to include in the regulation.

One independent energy policy specialist, who was unaffiliated with the study, described the analysis a “very useful addition” after years in which parts of the automotive sector argued there was insufficient information to accurately evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” the expert said. “Any policy changes regarding PHEVs should be implemented with utmost care and in the light of this data.”