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Plug-in hybrid electric vehicles produce almost 5x greater planet-heating emissions than official data show, as per a new analysis.

Growing Discrepancy Between Official and Actual Emissions

Statistics shows that PHEVs emit just 19% less CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a advocacy organization. This differs sharply with lab tests, which suggested a three-quarters reduction in emissions.

Analysts studied data from in-vehicle energy use meters of eight hundred thousand 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 figures, up from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are falling,” said a senior researcher involved in the study. “That discrepancy is widening and poses a significant problem. As a result, PHEVs emit almost as heavily as petrol vehicles.”

Primary Factors Driving the Emissions Gap

Researchers attributed the majority of the gap to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric power compared to total mileage. They found that just a quarter of driving was completed in electric mode, whereas official assumptions suggested 84%.

Even, when operating in EV mode, emission levels were well above lab estimates. This occurred because electric motors were not strong enough to operate independently, resulting to combustion motors burning fossil fuels for nearly one-third of the travel completed in EV mode.

Policy and Financial Implications

According to estimates, the underestimation of PHEV CO2 output allowed four large automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would pay about €500 more per year in running expenses than would be assumed under lab conditions.

“The bold statements that automakers often promote about their PHEV cars are obviously far from the mark,” commented a automotive analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little better than regular petrol and diesel cars in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Industry Pressure

Plug-in hybrid vehicles have lately been brought again into policy discussions as automakers have pressed the European Union to weaken CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive sector and resistance from member states with large car industries.

Some high-level politicians have suggested PHEVs as a possible “flexibility” option to include in the regulation.

One external energy economics expert, who was not involved with the research, called the analysis a “very useful addition” after years in which segments of the car industry argued there was too little data to accurately evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the gap between lab and actual PHEV energy use and CO₂ output is significantly greater than for gasoline or conventional cars,” the expert stated. “All regulatory adjustments concerning PHEVs should be made with utmost care and considering that data.”