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PHEVs emit almost five times greater planet-heating pollution than official data indicate, according to a new report.

Growing Gap In Lab and Real-World Emissions

Statistics shows that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to research conducted by a non-profit group. This contrasts sharply with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers examined information from in-vehicle fuel consumption meters of eight hundred thousand cars registered in the EU from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, up from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” said a senior analyst participating in the study. “This discrepancy is widening and creates a serious problem. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Primary Reasons Behind the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers driven in battery power relative to overall mileage. The team determined that only a quarter of driving was completed in EV mode, whereas lab assumptions assumed over four-fifths.

Even, when running in EV mode, pollution amounts were well above official projections. This occurred because electric motors were insufficiently powerful enough to operate independently, leading to combustion motors using fossil fuels for nearly one-third of the travel completed in EV mode.

Policy and Financial Consequences

According to calculations, the lowballing of PHEV emissions enabled several major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Additionally, owners of PHEVs would pay about €500 extra annually in operating costs than would be assumed under laboratory conditions.

“The strong claims that manufacturers like to make about their PHEV cars are clearly far from the mark,” commented a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Industry Lobbying

Hybrid cars have lately been drawn again into political debates as carmakers have lobbied the EU to weaken CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with significant automotive manufacturing.

Several high-level politicians have suggested PHEVs as a potential “compromise” option to include in the regulation.

One external energy policy expert, who was not involved with the study, described the analysis a “highly valuable contribution” after a long period in which parts of the automotive industry claimed there was insufficient data to properly evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional cars,” the expert stated. “Any regulatory adjustments regarding PHEVs should be made with extreme caution and in the light of this data.”