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Plug-in hybrid electric vehicles release almost five times greater planet-heating pollution than official figures show, according to a recent analysis.

Growing Discrepancy Between Official and Real-World CO2 Output

Statistics reveals that PHEVs emit just 19% less CO₂ than conventional petrol and diesel vehicles, according to research conducted by a non-profit group. That differs sharply with lab estimates, which assumed a three-quarters decrease in emissions.

Researchers studied data from in-vehicle energy use monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” stated a senior analyst participating in the study. “This gap is widening and creates a significant problem. Consequently, PHEVs pollute almost as much as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers linked most of the gap to inflated estimates of the “utility factor” – the percentage of miles travelled in electric power relative to total mileage. They found that only a quarter of driving was completed in EV mode, while official assumptions assumed over four-fifths.

Additionally, when operating in EV mode, emission levels were well above official estimates. This occurred because electric motors were insufficiently powerful sufficient to function independently, resulting to combustion motors burning gasoline for almost one-third of the distance completed in EV mode.

Policy and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output allowed several major automaker groups to escape over €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs could spend about €500 extra per year in running expenses than is estimated under lab conditions.

“The strong claims that automakers often promote about their PHEV cars are obviously far from the mark,” commented a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running expenses.”

Political Debate and Industry Pressure

Plug-in hybrid vehicles have lately been brought back into political discussions as automakers have lobbied the EU to weaken CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with large car industries.

Some senior officials have proposed plug-in hybrids as a potential “compromise” option to introduce in the regulation.

An external energy economics expert, who was not involved with the study, described the report a “highly valuable contribution” after a long period in which segments of the automotive industry argued there was too little data to accurately assess real-world CO2 output.

“The results show, without question, that the difference in lab and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or conventional vehicles,” the expert stated. “All regulatory adjustments regarding PHEVs should be implemented with utmost caution and considering that data.”