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Plug-in hybrid electric vehicles produce nearly 5x more planet-heating pollution than official figures show, as per a new report.

Widening Gap In Lab and Real-World CO2 Output

Statistics reveals that PHEVs release just 19% lower CO₂ than conventional gas and diesel cars, according to analysis conducted by a advocacy organization. This differs significantly with lab estimates, which suggested a three-quarters reduction in emissions.

Analysts examined information from in-vehicle fuel consumption monitors of eight hundred thousand cars sold in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” stated a lead researcher involved in the report. “That gap is growing and creates a significant issue. Consequently, PHEVs emit almost as heavily as petrol cars.”

Key Factors Behind the Emissions Gap

Researchers linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in battery power compared to total distance. They determined that just 27% of travel was done in electric mode, whereas lab estimates assumed 84%.

Even, when operating in electric mode, emission levels were well above official projections. This happened because EV motors were insufficiently powerful enough to operate alone, resulting to combustion motors burning fossil fuels for nearly a third of the distance completed in EV mode.

Policy and Economic Consequences

Based on estimates, the underestimation of PHEV emissions allowed four major carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 more per year in running costs than is estimated under lab tests.

“The strong statements that automakers often promote about their PHEV vehicles are obviously far from the truth,” commented a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have recently been drawn again into political debates as carmakers have pressed the EU to weaken CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with large car manufacturing.

Some senior politicians have proposed PHEVs as a possible “flexibility” solution to introduce in the regulation.

One independent energy economics specialist, who was unaffiliated with the study, described the analysis a “very useful contribution” after a long period in which parts of the automotive industry claimed there was insufficient information to accurately evaluate actual CO2 output.

“The results show, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or diesel cars,” they said. “All regulatory changes regarding PHEVs should be implemented with extreme care and in the light of that evidence.”