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Plug-in hybrid electric vehicles emit almost five times greater global warming pollution than official figures indicate, as per a recent report.

Widening Discrepancy In Lab and Real-World Emissions

Statistics shows that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel cars, based on research carried out by a non-profit organization. This differs significantly with lab tests, which suggested a three-quarters decrease in pollution.

Researchers examined data from in-vehicle energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” said a senior researcher involved in the report. “That gap is widening and creates a significant issue. As a result, PHEVs emit nearly as much as petrol cars.”

Key Factors Behind the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers driven in battery mode relative to overall distance. The team determined that just a quarter of driving was done in electric mode, while official estimates assumed over four-fifths.

Even, when running in EV mode, emission amounts were significantly higher than official projections. That occurred because EV motors were insufficiently powerful enough to function alone, resulting to engines using gasoline for nearly a third of the distance covered in electric mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output allowed several large automaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs would pay about €500 extra annually in running expenses than would be estimated under lab tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are obviously way off the mark,” commented a transport expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn back into policy debates as automakers have pressed the EU to weaken CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with significant car industries.

Some senior politicians have suggested plug-in hybrids as a possible “flexibility” option to introduce in the regulation.

One external energy policy specialist, who was not involved with the study, described the report a “highly valuable contribution” after years in which segments of the automotive industry claimed there was too little information to properly evaluate actual CO2 output.

“The results demonstrate, without question, that the difference in lab and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or conventional vehicles,” they stated. “Any regulatory adjustments regarding PHEVs should be implemented with utmost caution and considering this data.”