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PHEVs emit nearly 5x more global warming emissions than lab-reported figures show, as per a new report.

Widening Gap In Official and Real-World CO2 Output

Statistics reveals that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel cars, according to research carried out by a non-profit organization. This differs significantly with lab estimates, which assumed a three-quarters reduction in pollution.

Researchers examined information from in-vehicle energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while official emissions are falling,” stated a senior analyst participating in the study. “This gap is growing and creates a significant issue. As a result, PHEVs pollute almost as much as petrol vehicles.”

Primary Factors Driving the Discrepancy

Researchers linked the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in electric power compared to total distance. They found that just 27% of driving was done in electric mode, while official assumptions suggested over four-fifths.

Even, when operating in EV mode, emission levels were significantly higher than official estimates. This occurred because electric motors were not strong sufficient to operate alone, resulting to engines using fossil fuels for nearly a third of the distance covered in EV mode.

Policy and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output enabled several major automaker groups to avoid over €5bn in fines between 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 extra annually in operating expenses than is assumed under laboratory tests.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are obviously far from the truth,” commented a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are helping the environment and saving money. Actually, PHEVs are little improved than standard gas and diesel cars in terms of fuel use, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Pressure

Plug-in hybrid cars have recently been drawn back into policy discussions as carmakers have pressed the EU to weaken CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with significant automotive manufacturing.

Some high-level officials have proposed PHEVs as a possible “compromise” option to introduce in the legislation.

One independent energy policy expert, who was unaffiliated with the study, called the report a “highly valuable contribution” after years in which segments of the car industry claimed there was too little information to accurately assess actual CO2 output.

“These findings show, without question, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel vehicles,” they said. “All policy changes regarding PHEVs should be made with utmost care and in the light of that evidence.”