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Plug-in hybrid electric vehicles release nearly 5x more planet-heating pollution than lab-reported data indicate, according to a recent report.

Widening Gap Between Official and Actual Emissions

Statistics shows that PHEVs release just 19% less CO₂ than traditional petrol and diesel cars, based on research carried out by a advocacy organization. This contrasts sharply with laboratory tests, which suggested a 75% decrease in emissions.

Analysts studied information from onboard energy use meters of eight hundred thousand vehicles registered in the EU from 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are rising, while official emissions are decreasing,” stated a lead analyst participating in the report. “That gap is growing and poses a significant problem. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Key Factors Behind the Discrepancy

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of miles travelled in electric mode compared to total mileage. The team found that only a quarter of driving was done in EV mode, whereas lab assumptions suggested 84%.

Even, when running in electric mode, emission levels were significantly higher than official estimates. That happened because EV motors were insufficiently powerful sufficient to function alone, leading to combustion motors burning gasoline for almost a third of the distance completed in electric mode.

Regulatory and Economic Consequences

Based on estimates, the underestimation of PHEV emissions allowed four large carmaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ standards.

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

“The bold claims that automakers often promote about their PHEV cars are clearly far from the truth,” commented a transport analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little improved than regular petrol and diesel cars in terms of energy use, CO₂ production, and running expenses.”

Political Discussion and Automotive Lobbying

Hybrid vehicles have lately been brought back into policy debates as carmakers have pressed the European Union to weaken CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and opposition from EU countries with large car manufacturing.

Some high-level officials have suggested plug-in hybrids as a possible “compromise” option to introduce in the regulation.

One independent energy economics expert, who was not involved with the study, called the report a “highly valuable addition” after years in which segments of the automotive sector claimed there was insufficient data to accurately assess actual emissions.

“These findings show, without question, that the gap in lab and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional cars,” the expert stated. “All regulatory changes regarding PHEVs should be made with utmost caution and in the light of this evidence.”