🔗 Share this article

Plug-in hybrid electric vehicles release nearly five times more global warming pollution than official figures indicate, according to a recent analysis.

Widening Discrepancy In Official and Actual CO2 Output

Statistics reveals that PHEVs emit only 19% lower CO₂ than conventional gas and diesel vehicles, based on research carried out by a non-profit group. That differs sharply with lab estimates, which assumed a 75% decrease in emissions.

Researchers examined information from in-vehicle energy use monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported figures are falling,” said a lead analyst involved in the report. “That gap is widening and poses a significant problem. As a result, PHEVs emit nearly as much as petrol vehicles.”

Key Factors Driving the Discrepancy

Researchers linked most of the gap to inflated estimates of the “utility factor” – the ratio of miles driven in battery power compared to overall distance. The team determined that only 27% of travel was completed in electric mode, while official assumptions assumed over four-fifths.

Even, when running in EV mode, pollution levels were well above official estimates. This occurred because electric motors were not strong sufficient to function alone, leading to combustion motors using gasoline for almost a third of the travel completed in electric mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV CO2 output allowed several major carmaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 more per year in operating costs than is assumed under laboratory conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid cars are obviously far from the mark,” stated a transport analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have lately been drawn back into political debates as automakers have lobbied the EU to relax CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and resistance from member states with significant car industries.

Some senior officials have suggested plug-in hybrids as a possible “compromise” option to introduce in the legislation.

One independent energy economics expert, who was not involved with the research, called the analysis a “highly valuable addition” after years in which segments of the automotive sector argued there was insufficient information to accurately evaluate real-world emissions.

“The results show, without question, that the difference in official and real-world PHEV energy use and CO₂ emissions is much, much greater than for petrol or diesel cars,” the expert stated. “All regulatory adjustments regarding PHEVs should be made with extreme care and considering this evidence.”