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Plug-in hybrid cars produce almost 5x greater global warming pollution than official data indicate, as per a new analysis.

Growing Gap In Lab and Actual CO2 Output

Statistics shows that PHEVs release just 19% less CO₂ than conventional gas and diesel cars, according to analysis carried out by a advocacy organization. That differs significantly with lab tests, which assumed a 75% decrease in emissions.

Analysts studied information from in-vehicle fuel consumption monitors of eight hundred thousand vehicles registered in the EU from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” stated a lead researcher involved in the study. “This discrepancy is widening and poses a serious issue. As a result, PHEVs emit almost as heavily as petrol cars.”

Key Reasons Behind the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in battery power relative to overall mileage. They determined that just a quarter of driving was done in electric mode, whereas lab assumptions suggested 84%.

Additionally, when operating in electric mode, emission levels were significantly higher than lab estimates. That occurred because EV motors were not strong enough to function independently, resulting to combustion motors using fossil fuels for almost a third of the travel completed in EV mode.

Regulatory and Financial Implications

Based on calculations, the underestimation of PHEV CO2 output allowed four major carmaker companies to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs could pay about €500 extra per year in running costs than would be estimated under laboratory conditions.

“The strong statements that automakers like to make about their PHEV cars are clearly far from the truth,” commented a transport analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little improved than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating expenses.”

Political Discussion and Automotive Lobbying

Hybrid cars have recently been brought back into policy discussions as automakers have lobbied the EU to relax CO₂ targets. A proposed prohibition on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with significant automotive manufacturing.

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

One independent energy policy expert, who was not involved with the study, described the analysis a “highly valuable addition” after a long period in which parts of the automotive sector claimed there was too little information to properly assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or conventional cars,” they said. “Any policy changes regarding PHEVs should be made with extreme caution and considering that data.”