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PHEVs emit almost five times greater planet-heating emissions than official figures indicate, according to a recent report.

Widening Discrepancy Between Lab and Actual Emissions

Statistics shows that PHEVs release only 19% less CO₂ than traditional gas and diesel vehicles, based on analysis carried out by a advocacy group. This differs significantly with laboratory estimates, which assumed a three-quarters decrease in pollution.

Researchers examined information from onboard energy use monitors of 800,000 cars sold in the EU from 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” stated a lead analyst involved in the report. “This discrepancy is widening and poses a significant problem. As a result, PHEVs pollute almost as much as petrol cars.”

Key Reasons Driving the Discrepancy

Analysts linked most of the gap to overestimates of the “utility factor” – the ratio of miles driven in battery mode compared to total mileage. The team found that just a quarter of driving was completed in EV mode, whereas official estimates suggested over four-fifths.

Even, when running in electric mode, pollution amounts were significantly higher than official estimates. This happened because electric motors were insufficiently powerful sufficient to function independently, leading to engines using gasoline for nearly one-third of the distance completed in electric mode.

Policy and Economic Consequences

Based on estimates, the underestimation of PHEV CO2 output enabled several major carmaker companies to escape over €5bn in penalties from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs would pay approximately €500 extra per year in operating costs than is assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their PHEV vehicles are clearly way off the mark,” commented a automotive analyst. “Consumers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting money. In reality, PHEVs are only slightly better than standard petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Political Discussion and Automotive Lobbying

Hybrid cars have recently been brought again into political debates as carmakers have pressed the EU to weaken CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the car industry and resistance from member states with significant car manufacturing.

Some high-level politicians have suggested PHEVs as a possible “flexibility” solution to include in the regulation.

An external energy policy expert, who was not involved with the research, described the report a “very useful addition” after years in which parts of the automotive industry claimed there was insufficient data to properly evaluate real-world CO2 output.

“The results show, without question, that the gap in official and real-world PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” the expert said. “All policy adjustments regarding PHEVs should be made with extreme caution and considering that evidence.”