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PHEVs emit nearly five times greater global warming emissions than official data indicate, according to a new report.

Widening Discrepancy In Lab and Real-World CO2 Output

Statistics reveals that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel cars, based on analysis carried out by a non-profit organization. That differs significantly with lab tests, which suggested a 75% decrease in emissions.

Analysts examined data from onboard energy use meters of eight hundred thousand cars registered in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” said a senior analyst involved in the report. “This discrepancy is growing and poses a significant problem. As a result, PHEVs pollute nearly as much as petrol cars.”

Primary Factors Driving the Discrepancy

Researchers attributed the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric power relative to total distance. They determined that just a quarter of driving was completed in EV mode, while lab estimates suggested 84%.

Additionally, when operating in EV mode, pollution levels were significantly higher than official projections. This occurred because EV motors were insufficiently powerful sufficient to operate alone, leading to combustion motors using gasoline for nearly one-third of the distance completed in EV mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV emissions allowed four major carmaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs would spend about €500 more per year in running expenses than would be assumed under laboratory tests.

“The strong statements that manufacturers often promote about their PHEV cars are clearly way off the truth,” stated a transport analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the planet and saving costs. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into policy discussions as carmakers have lobbied the European Union to relax CO₂ standards. A proposed ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with large automotive manufacturing.

Several senior officials have proposed plug-in hybrids as a potential “flexibility” solution to include in the regulation.

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

“The results show, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ output is much, much larger than for petrol or conventional vehicles,” the expert stated. “All policy adjustments concerning PHEVs should be implemented with extreme caution and in the light of that data.”