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Plug-in hybrid electric vehicles release nearly 5x more planet-heating emissions than official data show, as per a recent analysis.

Growing Gap In Lab and Real-World Emissions

Data reveals that PHEVs release just 19% less CO₂ than conventional petrol and diesel vehicles, according to research conducted by a non-profit group. This contrasts significantly with lab estimates, which suggested a three-quarters decrease in pollution.

Researchers studied information from in-vehicle energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” said a senior analyst participating in the report. “This discrepancy is growing and poses a serious issue. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Key Factors Behind the Emissions Gap

Analysts linked the majority of the difference to overestimates of the “utility factor” – the percentage of miles travelled in battery power relative to overall distance. They determined that only 27% of driving was done in electric mode, while official estimates assumed 84%.

Even, when running in electric mode, pollution amounts were significantly higher than lab estimates. This happened because EV motors were insufficiently powerful enough to function independently, leading to engines burning gasoline for nearly one-third of the distance covered in EV mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output allowed several major carmaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely simplifying compliance with EU average fleet CO₂ targets.

Additionally, owners of PHEVs could spend approximately €500 more per year in operating costs than is estimated under lab conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the mark,” commented a transport analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running expenses.”

Policy Discussion and Automotive Pressure

Plug-in hybrid cars have recently been brought back into political debates as carmakers have pressed the European Union to weaken CO₂ targets. A proposed ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car industry and opposition from EU countries with large automotive manufacturing.

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

One independent energy policy expert, who was not involved with the study, described the report a “very useful contribution” after years in which segments of the automotive sector claimed there was too little data to properly evaluate real-world emissions.

“The results demonstrate, without question, that the gap between official and real-world PHEV energy use and CO₂ output is significantly larger than for petrol or diesel cars,” they said. “All regulatory adjustments concerning PHEVs should be made with extreme caution and in the light of that data.”