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PHEVs produce nearly 5x greater planet-heating emissions than official figures show, according to a recent report.

Widening Discrepancy In Lab and Actual Emissions

Data shows that PHEVs emit just 19% less CO₂ than conventional petrol and diesel cars, based on research carried out by a advocacy group. That differs significantly with laboratory estimates, which suggested a 75% decrease in pollution.

Researchers examined data from onboard fuel consumption meters of 800,000 cars sold in the EU from 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” said a lead analyst participating in the study. “That gap is widening and creates a serious issue. Consequently, PHEVs pollute almost as much as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Researchers linked most of the gap to overestimates of the “electric driving share” – the ratio of miles driven in electric power compared to overall mileage. They determined that only a quarter of driving was completed in EV mode, while lab estimates assumed 84%.

Additionally, when operating in electric mode, pollution levels were well above lab projections. This occurred because EV motors were not strong enough to function alone, leading to engines using fossil fuels for almost one-third of the distance covered in electric mode.

Regulatory and Financial Implications

According to calculations, the lowballing of PHEV emissions allowed four large carmaker groups to escape more than €5bn in fines from 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend about €500 extra annually in running costs than is assumed under lab conditions.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are obviously way off the truth,” commented a transport expert. “Buyers are being duped into believing that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Political Discussion and Automotive Pressure

Hybrid vehicles have recently been drawn back into political debates as automakers have lobbied the European Union to weaken CO₂ standards. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the automotive sector and opposition from EU countries with large car manufacturing.

Several high-level officials have suggested PHEVs as a potential “flexibility” solution to introduce in the regulation.

One external energy policy expert, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after years in which segments of the automotive industry claimed there was insufficient information to accurately assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the gap in lab and actual PHEV fuel consumption and CO₂ output is much, much greater than for petrol or conventional cars,” the expert said. “Any regulatory adjustments concerning PHEVs should be made with utmost care and considering this evidence.”