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PHEVs emit almost five times greater global warming pollution than official figures indicate, as per a new report.

Widening Discrepancy Between Lab and Real-World Emissions

Statistics reveals that PHEVs emit only one-fifth lower CO₂ than traditional gas and diesel cars, based on research conducted by a non-profit organization. That differs sharply with lab estimates, which suggested a 75% reduction in emissions.

Researchers studied information from onboard energy use meters of 800,000 vehicles registered in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” said a lead researcher involved in the study. “That gap is growing and creates a serious problem. Consequently, PHEVs pollute almost as much as gasoline cars.”

Key Reasons Behind the Emissions Gap

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery mode compared to overall mileage. They determined that only a quarter of driving was done in EV mode, whereas lab assumptions assumed 84%.

Even, when running in electric mode, emission amounts were significantly higher than official projections. This happened because electric motors were insufficiently powerful sufficient to function independently, leading to engines burning fossil fuels for nearly a third of the distance completed in electric mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output allowed four large carmaker companies to avoid over €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 extra annually in operating costs than is assumed under laboratory tests.

“The strong claims that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the mark,” stated a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of energy consumption, CO₂ production, and running costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into political debates as carmakers have lobbied the European Union to weaken CO₂ standards. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from member states with significant automotive industries.

Some high-level politicians have proposed plug-in hybrids as a possible “compromise” option to introduce in the legislation.

One external energy economics expert, who was unaffiliated with the study, called the report a “very useful addition” after a long period in which segments of the car industry argued there was insufficient information to accurately evaluate actual CO2 output.

“The results show, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with extreme care and in the light of this evidence.”