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PHEVs produce nearly 5x more global warming pollution than official figures show, as per a new report.

Widening Gap In Lab and Real-World Emissions

Data shows that PHEVs emit only 19% lower CO₂ than conventional petrol and diesel cars, based on analysis conducted by a non-profit organization. This contrasts significantly with lab tests, which suggested a three-quarters decrease in pollution.

Analysts examined information from in-vehicle energy use monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” said a senior researcher involved in the study. “This gap is growing and creates a serious problem. As a result, PHEVs emit nearly as much as petrol cars.”

Primary Reasons Behind the Emissions Gap

Researchers attributed most of the gap to overestimates of the “utility factor” – the percentage of miles driven in battery power compared to total distance. The team found that just 27% of driving was done in electric mode, while lab estimates assumed 84%.

Even, when operating in EV mode, emission levels were well above lab projections. That occurred because electric motors were not strong sufficient to function independently, resulting to engines burning fossil fuels for almost a third of the distance completed in EV mode.

Policy and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output enabled several major carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend approximately €500 extra per year in operating costs than would be assumed under laboratory conditions.

“The strong statements that automakers like to make about their plug-in hybrid cars are obviously far from the mark,” stated a automotive expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Political Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been drawn back into political discussions as automakers have lobbied the EU to weaken CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the car sector and opposition from member states with significant automotive industries.

Some senior officials have suggested plug-in hybrids as a possible “flexibility” solution to include in the regulation.

An external energy economics expert, who was unaffiliated with the study, called the report a “very useful contribution” after a long period in which segments of the car sector argued there was insufficient information to accurately assess actual emissions.

“These findings demonstrate, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ output is much, much greater than for petrol or diesel cars,” the expert stated. “Any policy changes concerning PHEVs should be made with extreme caution and in the light of that evidence.”