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PHEVs emit almost 5x more planet-heating emissions than lab-reported data indicate, as per a new analysis.

Growing Discrepancy Between Lab and Actual Emissions

Statistics shows that PHEVs emit just one-fifth lower CO₂ than traditional petrol and diesel cars, according to research carried out by a advocacy group. This differs sharply with laboratory tests, which suggested a three-quarters reduction in pollution.

Analysts studied data from in-vehicle energy use meters of eight hundred thousand cars sold in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, up from three and a half times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” said a lead researcher participating in the study. “That gap is widening and creates a significant problem. Consequently, PHEVs pollute nearly as much as gasoline cars.”

Primary Reasons Driving the Discrepancy

Researchers linked most of the gap to overestimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to overall distance. They determined that only a quarter of travel was done in EV mode, while lab assumptions assumed 84%.

Even, when operating in EV mode, emission amounts were significantly higher than official estimates. That happened because electric motors were not strong sufficient to function independently, leading to engines burning fossil fuels for almost a third of the travel completed in EV mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV emissions allowed several large carmaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 extra annually in running costs than would be estimated under laboratory conditions.

“The bold statements that manufacturers often promote about their PHEV cars are obviously way off the truth,” commented a transport expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Political Debate and Industry Pressure

Hybrid vehicles have recently been brought back into political debates as automakers have pressed the EU to relax CO₂ standards. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense pressure from the car industry and opposition from EU countries with large car manufacturing.

Several senior politicians have suggested plug-in hybrids as a possible “compromise” solution to include in the regulation.

An independent energy policy specialist, who was not involved with the study, called the report a “very useful contribution” after a long period in which segments of the car sector argued there was too little data to accurately assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference between official and real-world PHEV energy use and CO₂ emissions is much, much larger than for gasoline or diesel cars,” they stated. “All regulatory adjustments regarding PHEVs should be implemented with utmost caution and considering that evidence.”