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PHEVs produce nearly five times more planet-heating pollution than lab-reported figures show, according to a new analysis.

Growing Gap Between Official and Actual CO2 Output

Data reveals that PHEVs release just 19% less CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a advocacy group. This contrasts sharply with lab tests, which suggested a 75% decrease in emissions.

Analysts examined information from onboard fuel consumption monitors of eight hundred thousand vehicles registered in the EU between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” said a lead researcher participating in the report. “That gap is widening and poses a significant issue. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Key Reasons Behind the Discrepancy

Analysts attributed most of the difference to overestimates of the “utility factor” – the ratio of miles driven in battery power relative to total distance. The team determined that just 27% of travel was done in EV mode, while lab assumptions assumed 84%.

Additionally, when operating in EV mode, emission amounts were well above official estimates. That happened because electric motors were not strong sufficient to operate alone, resulting to combustion motors burning fossil fuels for nearly a third of the travel covered in EV mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV emissions allowed four large carmaker companies to avoid over €5bn in fines between 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ targets.

Additionally, owners of PHEVs would spend approximately €500 extra per year in running costs than would be estimated under lab conditions.

“The strong claims that automakers like to make about their PHEV cars are obviously way off the mark,” stated a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little improved than standard gas and diesel vehicles in terms of energy consumption, CO₂ production, and running costs.”

Policy Debate and Industry Lobbying

Hybrid cars have lately been drawn again into political discussions as automakers have lobbied the European Union to weaken CO₂ standards. A planned ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the car sector and opposition from member states with significant car manufacturing.

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

An external energy policy expert, who was not involved with the study, described the analysis a “very useful addition” after years in which segments of the automotive sector argued there was insufficient information to accurately assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel cars,” the expert said. “All regulatory adjustments regarding PHEVs should be made with utmost caution and in the light of that evidence.”