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Plug-in hybrid electric vehicles emit nearly five times greater global warming pollution than official figures indicate, as per a recent analysis.

Growing Discrepancy Between Lab and Actual CO2 Output

Data reveals that PHEVs release just one-fifth less CO₂ than conventional gas and diesel vehicles, based on research carried out by a non-profit group. That differs sharply with lab tests, which suggested a three-quarters reduction in emissions.

Analysts studied data from in-vehicle fuel consumption meters of 800,000 cars registered in the EU from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported figures are decreasing,” said a senior analyst involved in the study. “This discrepancy is growing and creates a significant problem. Consequently, PHEVs pollute nearly as much as petrol cars.”

Primary Factors Behind the Emissions Gap

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric mode relative to total mileage. The team found that just 27% of driving was completed in EV mode, whereas official assumptions suggested over four-fifths.

Even, when operating in EV mode, pollution amounts were well above official projections. That occurred because electric motors were insufficiently powerful enough to operate alone, leading to engines using fossil fuels for nearly one-third of the travel completed in electric mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output allowed several large carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs would spend about €500 more per year in operating expenses than would be assumed under lab conditions.

“The bold statements that manufacturers often promote about their PHEV vehicles are clearly way off the mark,” commented a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of energy consumption, CO₂ production, and running costs.”

Political Discussion and Automotive Pressure

Hybrid vehicles have recently been drawn again into policy debates as automakers have pressed the EU to relax CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with large car manufacturing.

Several senior politicians have suggested plug-in hybrids as a potential “compromise” solution to include in the regulation.

An external energy economics specialist, who was unaffiliated with the research, called the analysis a “very useful addition” after years in which segments of the car industry claimed there was too little information to accurately assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ output is significantly larger than for petrol or diesel cars,” they stated. “Any regulatory changes regarding PHEVs should be made with utmost care and in the light of that evidence.”