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PHEVs release nearly five times greater global warming emissions than official figures show, according to a recent report.

Growing Gap In Lab and Real-World Emissions

Data reveals that PHEVs emit only one-fifth less CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a advocacy group. That contrasts sharply with laboratory estimates, which assumed a three-quarters reduction in emissions.

Researchers studied information from in-vehicle fuel consumption monitors of 800,000 vehicles registered in the EU between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” said a senior researcher participating in the study. “That gap is growing and poses a serious issue. Consequently, PHEVs pollute almost as heavily as petrol cars.”

Key Reasons Driving the Emissions Gap

Analysts attributed the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery mode relative to total distance. The team determined that only a quarter of travel was done in electric mode, while official assumptions assumed over four-fifths.

Even, when operating in electric mode, pollution levels were well above lab estimates. This occurred because EV motors were insufficiently powerful enough to function alone, resulting to engines using gasoline for almost one-third of the travel completed in EV mode.

Regulatory and Financial Implications

According to calculations, the underestimation of PHEV CO2 output enabled four large carmaker companies to avoid over €5bn in penalties from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would pay about €500 extra annually in operating costs than is estimated under lab conditions.

“The bold statements that manufacturers like to make about their PHEV cars are obviously far from the mark,” commented a automotive analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little better than standard gas and diesel cars in terms of energy consumption, CO₂ emissions, and operating costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have recently been brought back into political debates as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the car industry and opposition from member states with large car manufacturing.

Some senior officials have proposed plug-in hybrids as a possible “compromise” solution to include in the regulation.

One external energy economics expert, who was unaffiliated with the study, described the analysis a “highly valuable contribution” after years in which parts of the car sector claimed there was too little data to accurately evaluate real-world CO2 output.

“The results show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel cars,” the expert stated. “All regulatory changes concerning PHEVs should be implemented with extreme caution and in the light of that evidence.”