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PHEVs emit almost 5x more planet-heating emissions than lab-reported data indicate, according to a new report.

Growing Gap Between Lab and Real-World CO2 Output

Statistics shows that PHEVs release only 19% lower CO₂ than conventional petrol and diesel cars, based on analysis conducted by a advocacy group. This differs significantly with lab estimates, which assumed a three-quarters decrease in pollution.

Researchers studied data from onboard fuel consumption meters of 800,000 vehicles registered in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, up from 3.5 times in 2021.

“Actual emissions are increasing, while official figures are falling,” said a senior researcher involved in the report. “That discrepancy is widening and poses a significant issue. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Key Factors Behind the Discrepancy

Analysts attributed most of the gap to overestimates of the “utility factor” – the ratio of miles driven in electric power relative to total mileage. They determined that only 27% of driving was done in electric mode, while official assumptions suggested 84%.

Additionally, when running in electric mode, emission levels were significantly higher than lab estimates. That happened because EV motors were insufficiently powerful enough to function independently, resulting to combustion motors using fossil fuels for almost a third of the travel completed in electric mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed four large automaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 extra per year in running expenses than would be estimated under lab conditions.

“The bold statements that manufacturers like to make about their PHEV vehicles are obviously way off the mark,” commented a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Discussion and Industry Lobbying

Hybrid cars have lately been brought again into political discussions as carmakers have lobbied the EU to relax CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the car sector and resistance from member states with significant car industries.

Some senior officials have suggested PHEVs as a potential “flexibility” option to introduce in the legislation.

One independent energy policy expert, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after years in which parts of the car industry claimed there was insufficient information to accurately evaluate actual CO2 output.

“These findings show, beyond any doubt, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” they stated. “Any regulatory adjustments concerning PHEVs should be implemented with extreme caution and considering that data.”