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PHEVs release nearly 5x more planet-heating pollution than lab-reported figures indicate, according to a new report.

Growing Gap Between Official and Actual CO2 Output

Data reveals that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy organization. This contrasts significantly with laboratory tests, which suggested a three-quarters reduction in emissions.

Analysts studied data from in-vehicle energy use meters of eight hundred thousand cars registered in Europe between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, up from 3.5 times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” said a senior analyst involved in the report. “That discrepancy is widening and poses a serious problem. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Factors Driving the Emissions Gap

Researchers linked most of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers travelled in electric power relative to total mileage. They found that just 27% of travel was done in electric mode, whereas lab assumptions suggested over four-fifths.

Additionally, when running in EV mode, emission levels were significantly higher than official projections. That happened because electric motors were not strong enough to function independently, leading to combustion motors burning gasoline for nearly a third of the distance covered in electric mode.

Regulatory and Financial Implications

According to estimates, the lowballing of PHEV CO2 output allowed several large carmaker groups to avoid more than €5bn in fines between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs could pay approximately €500 extra annually in operating costs than would be assumed under lab tests.

“The strong claims that manufacturers often promote about their PHEV cars are clearly way off the truth,” commented a transport analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and saving money. Actually, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and running expenses.”

Policy Debate and Industry Pressure

Hybrid cars have recently been drawn back into policy debates as carmakers have pressed the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with large car industries.

Several senior politicians have suggested PHEVs as a possible “flexibility” option to introduce in the legislation.

One independent energy economics expert, who was not involved with the study, called the analysis a “very useful addition” after years in which parts of the car sector claimed there was too little data to accurately assess actual CO2 output.

“These findings show, without question, that the difference in lab and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel cars,” they said. “All policy adjustments concerning PHEVs should be made with utmost caution and considering this data.”