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Plug-in hybrid cars produce almost 5x greater planet-heating emissions than lab-reported figures show, as per a new analysis.

Widening Gap Between Lab and Actual Emissions

Statistics shows that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel vehicles, based on research carried out by a non-profit group. This differs sharply with lab tests, which suggested a 75% decrease in pollution.

Analysts studied information from in-vehicle energy use meters of eight hundred thousand vehicles registered in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official figures are falling,” said a lead researcher participating in the report. “This gap is widening and poses a significant issue. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Analysts linked most of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to total distance. They found that only a quarter of travel was done in electric mode, while official assumptions suggested 84%.

Additionally, when running in EV mode, emission amounts were well above lab projections. That occurred because electric motors were insufficiently powerful sufficient to function independently, leading to engines burning fossil fuels for almost a third of the travel completed in EV mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV emissions allowed four large automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs could pay about €500 more per year in running costs than is assumed under lab tests.

“The strong statements that automakers like to make about their PHEV cars are clearly far from the truth,” commented a automotive expert. “Consumers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Pressure

Hybrid cars have lately been brought again into policy discussions as carmakers have pressed the European Union to relax CO₂ targets. A proposed ban on new combustion engine cars in 2035 has faced heavy lobbying from the automotive sector and resistance from EU countries with large car manufacturing.

Some senior politicians have proposed PHEVs as a possible “compromise” option to include in the regulation.

An external energy policy expert, who was not involved with the research, called the report a “highly valuable contribution” after a long period in which parts of the car sector claimed there was insufficient data to accurately assess actual CO2 output.

“The results show, beyond any doubt, that the difference in official and actual PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” the expert stated. “All policy adjustments regarding PHEVs should be made with utmost caution and in the light of this data.”