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Plug-in hybrid cars produce almost 5x greater global warming pollution than official figures show, as per a new report.

Widening Discrepancy In Official and Real-World CO2 Output

Statistics reveals that PHEVs release only one-fifth less CO₂ than conventional gas and diesel cars, according to analysis carried out by a non-profit group. That differs significantly with lab estimates, which assumed a three-quarters decrease in pollution.

Researchers studied data from in-vehicle energy use monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a lead analyst involved in the report. “This discrepancy is growing and creates a serious problem. As a result, PHEVs emit nearly as much as gasoline vehicles.”

Primary Factors Driving the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the percentage of miles driven in battery mode compared to overall distance. The team found that just a quarter of driving was completed in electric mode, while lab estimates assumed 84%.

Even, when operating in electric mode, emission levels were significantly higher than official estimates. This occurred because EV motors were not strong enough to operate independently, leading to engines burning gasoline for nearly one-third of the distance covered in EV mode.

Policy and Economic Implications

According to calculations, the underestimation of PHEV emissions allowed several major carmaker groups to escape more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ targets.

Additionally, owners of PHEVs could spend about €500 more per year in operating expenses than is estimated under lab tests.

“The bold statements that automakers like to make about their PHEV cars are clearly far from the mark,” commented a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Political Debate and Automotive Pressure

Plug-in hybrid cars have recently been brought back into political debates as carmakers have pressed the EU to relax CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car sector and resistance from member states with significant car manufacturing.

Several high-level officials have suggested PHEVs as a potential “flexibility” solution to introduce in the legislation.

An external energy policy specialist, who was not involved with the study, described the analysis a “very useful contribution” after a long period in which parts of the automotive sector argued there was too little data to properly evaluate actual emissions.

“The results show, without question, that the difference in lab and real-world PHEV energy use and CO₂ emissions is much, much larger than for petrol or conventional cars,” they stated. “All policy adjustments regarding PHEVs should be made with utmost caution and in the light of that data.”