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Plug-in hybrid electric vehicles produce almost 5x greater global warming pollution than lab-reported data show, as per a new report.

Growing Discrepancy In Official and Real-World CO2 Output

Statistics shows that PHEVs emit only 19% lower CO₂ than traditional petrol and diesel cars, based on research carried out by a advocacy group. This contrasts sharply with lab estimates, which suggested a 75% decrease in emissions.

Analysts studied data from in-vehicle energy use meters of 800,000 cars sold in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are falling,” stated a senior researcher involved in the study. “This discrepancy is growing and creates a significant issue. As a result, PHEVs pollute nearly as heavily as gasoline vehicles.”

Key Factors Behind the Emissions Gap

Researchers linked most of the gap to inflated estimates of the “electric driving share” – the percentage of miles travelled in battery mode relative to total mileage. The team found that only a quarter of driving was completed in electric mode, while official assumptions suggested over four-fifths.

Even, when running in electric mode, pollution amounts were well above official projections. That happened because electric motors were not strong enough to operate independently, leading to engines burning gasoline for almost one-third of the distance completed in electric mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV emissions enabled several large carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 more annually in operating costs than is estimated under laboratory tests.

“The bold claims that manufacturers like to make about their PHEV vehicles are clearly far from the truth,” commented a transport expert. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Political Discussion and Industry Pressure

Plug-in hybrid vehicles have lately been brought back into political debates as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with significant car manufacturing.

Some senior politicians have suggested PHEVs as a possible “flexibility” option to introduce in the legislation.

One independent energy policy expert, who was not involved with the research, called the report a “highly valuable addition” after a long period in which parts of the car sector argued there was insufficient information to properly evaluate real-world emissions.

“These findings show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ output is much, much greater than for petrol or diesel vehicles,” the expert said. “All regulatory adjustments concerning PHEVs should be made with utmost caution and in the light of this evidence.”