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Plug-in hybrid cars release almost 5x more global warming emissions than lab-reported data indicate, according to a new report.

Widening Gap In Lab and Real-World Emissions

Data shows that PHEVs release just 19% lower CO₂ than conventional gas and diesel cars, based on analysis carried out by a non-profit organization. This differs sharply with lab tests, which assumed a three-quarters decrease in pollution.

Researchers studied information from in-vehicle energy use monitors of 800,000 cars sold in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are falling,” stated a lead analyst involved in the report. “This gap is growing and creates a significant issue. As a result, PHEVs pollute nearly as much as gasoline vehicles.”

Key Factors Behind the Emissions Gap

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in battery mode compared to total mileage. The team determined that just 27% of driving was completed in electric mode, whereas official assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution levels were significantly higher than official projections. That happened because EV motors were insufficiently powerful enough to operate alone, resulting to combustion motors burning gasoline for almost a third of the travel covered in EV mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV emissions enabled four major carmaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely easing compliance 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 conditions.

“The bold statements that manufacturers often promote about their plug-in hybrid vehicles are obviously way off the truth,” stated a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are little improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Debate and Industry Lobbying

Hybrid vehicles have lately been brought back into policy discussions as automakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with significant car manufacturing.

Some senior politicians have proposed plug-in hybrids as a possible “flexibility” solution to introduce in the regulation.

One independent energy policy specialist, who was not involved with the study, described the analysis a “highly valuable addition” after years in which parts of the car industry claimed there was insufficient data to accurately assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or diesel cars,” they stated. “All policy adjustments regarding PHEVs should be implemented with extreme care and in the light of that evidence.”