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Plug-in hybrid electric vehicles emit almost five times more planet-heating pollution than official figures indicate, as per a new report.

Widening Gap In Lab and Real-World Emissions

Data shows that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel cars, based on analysis conducted by a advocacy organization. This contrasts significantly with laboratory estimates, which suggested a 75% reduction in pollution.

Analysts studied data from onboard energy use meters of 800,000 cars sold in the EU between 2021 and 2023. They found 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 CO2 output are increasing, while lab-reported emissions are falling,” stated a senior researcher participating in the study. “This gap is widening and creates a significant problem. As a result, PHEVs pollute almost as much as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Researchers linked most of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in electric mode compared to overall mileage. They found that just a quarter of driving was done in electric mode, while official estimates suggested 84%.

Even, when operating in EV mode, pollution amounts were well above lab projections. This happened because EV motors were insufficiently powerful sufficient to function independently, leading to engines burning fossil fuels for nearly one-third of the distance completed in electric mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV emissions enabled several large carmaker groups to avoid over €5bn in fines between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay approximately €500 extra per year in operating costs than is assumed under lab conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the truth,” stated a transport expert. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the planet and saving costs. Actually, PHEVs are little improved than standard petrol and diesel cars in terms of fuel use, CO₂ emissions, and operating costs.”

Political Debate and Automotive Pressure

Hybrid vehicles have lately been brought back into political debates as automakers have lobbied the EU to relax CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the car sector and opposition from member states with large car manufacturing.

Several senior officials have proposed PHEVs 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 addition” after years in which parts of the automotive sector claimed there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the difference in official and real-world PHEV energy use and CO₂ emissions is significantly larger than for gasoline or diesel cars,” they stated. “Any policy changes regarding PHEVs should be made with extreme caution and considering that evidence.”