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Plug-in hybrid electric vehicles emit nearly 5x more global warming emissions than lab-reported figures indicate, as per a new analysis.

Growing Gap Between Lab and Actual CO2 Output

Statistics shows that PHEVs emit only 19% less CO₂ than traditional petrol and diesel vehicles, according to research conducted by a non-profit organization. That contrasts sharply with laboratory tests, which suggested a 75% reduction in emissions.

Researchers studied information from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from three and a half times in 2021.

“Actual emissions are increasing, while lab-reported emissions are decreasing,” stated a lead researcher involved in the study. “That discrepancy is growing and creates a serious problem. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Key Reasons Behind the Emissions Gap

Analysts linked most of the difference to overestimates of the “utility factor” – the percentage of miles travelled in battery power relative to overall distance. The team found that just 27% of driving was done in electric mode, while lab assumptions assumed 84%.

Even, when operating in electric mode, emission levels were significantly higher than official projections. That occurred because EV motors were insufficiently powerful enough to operate alone, resulting to engines burning fossil fuels for almost one-third of the travel completed in EV mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV emissions allowed several large automaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs would pay about €500 extra annually in operating costs than is assumed under lab tests.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are obviously far from the mark,” commented a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have lately been brought again into political discussions as carmakers have lobbied the EU to weaken CO₂ targets. A planned ban on new internal combustion vehicles in 2035 has faced intense lobbying from the car sector and opposition from EU countries with significant car manufacturing.

Some senior politicians have proposed plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

One independent energy economics specialist, who was unaffiliated with the study, called the analysis a “highly valuable contribution” after a long period in which parts of the automotive industry claimed there was insufficient information to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ output is much, much greater than for petrol or diesel vehicles,” they said. “All policy adjustments concerning PHEVs should be implemented with utmost caution and considering this evidence.”