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PHEVs release almost 5x greater planet-heating emissions than lab-reported figures indicate, according to a new report.

Growing Gap In Lab and Real-World CO2 Output

Data shows that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel cars, according to research conducted by a non-profit group. That differs significantly with laboratory estimates, which suggested a three-quarters decrease in emissions.

Analysts examined information from onboard fuel consumption meters of eight hundred thousand cars sold in Europe from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while official emissions are decreasing,” said a senior analyst involved in the study. “This discrepancy is widening and creates a significant problem. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Key Factors Behind the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric mode compared to total distance. They determined that only a quarter of travel was done in EV mode, whereas official assumptions assumed 84%.

Even, when operating in electric mode, pollution levels were well above official estimates. This happened because EV motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors using gasoline for almost one-third of the travel covered in EV mode.

Regulatory and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several large automaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

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

“The strong statements that automakers like to make about their plug-in hybrid vehicles are obviously far from the mark,” stated a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the planet and saving money. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Policy Discussion and Automotive Lobbying

Hybrid vehicles have lately been drawn again into political debates as carmakers have pressed the EU to weaken CO₂ standards. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive industry and resistance from member states with large car industries.

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

An external energy economics specialist, who was unaffiliated with the research, called the analysis a “highly valuable addition” after a long period in which parts of the car industry argued there was too little data to properly assess actual emissions.

“The results demonstrate, beyond any doubt, that the gap between official and real-world PHEV energy use and CO₂ output is significantly greater than for gasoline or conventional cars,” they stated. “All regulatory adjustments regarding PHEVs should be implemented with extreme caution and in the light of that evidence.”