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Plug-in hybrid electric vehicles release almost five times greater planet-heating emissions than lab-reported data show, as per a recent analysis.

Widening Discrepancy Between Official and Real-World Emissions

Statistics reveals that PHEVs release just one-fifth lower CO₂ than traditional gas and diesel cars, based on analysis carried out by a advocacy group. That contrasts sharply with lab estimates, which assumed a 75% decrease in emissions.

Analysts studied data from in-vehicle energy use monitors of 800,000 cars registered in the EU from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported figures are falling,” said a lead analyst involved in the report. “This discrepancy is growing and creates a significant issue. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Key Factors Behind the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in battery power compared to total distance. They found that just 27% of driving was completed in EV mode, while lab assumptions assumed over four-fifths.

Even, when operating in EV mode, emission levels were significantly higher than lab estimates. This occurred because electric motors were insufficiently powerful enough to function alone, leading to engines using gasoline for nearly a third of the distance completed in electric mode.

Policy and Economic Implications

Based on calculations, the underestimation of PHEV emissions allowed several major automaker companies to avoid over €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Additionally, owners of PHEVs would spend approximately €500 extra per year in running costs than would be assumed under lab tests.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are obviously way off the mark,” stated a automotive analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little better than standard petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Industry Pressure

Hybrid vehicles have lately been drawn again into political discussions as carmakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced heavy pressure from the car sector and resistance from EU countries with significant car manufacturing.

Several high-level officials have suggested plug-in hybrids as a possible “compromise” solution to include in the regulation.

One independent energy policy expert, who was not involved with the study, called the report a “highly valuable contribution” after a long period in which segments of the automotive sector argued there was insufficient data to accurately assess real-world CO2 output.

“These findings demonstrate, without question, that the difference between official and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel cars,” they stated. “All policy changes regarding PHEVs should be made with extreme care and considering that evidence.”