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PHEVs emit almost five times greater global warming emissions than lab-reported data show, as per a recent report.

Growing Gap Between Official and Actual CO2 Output

Statistics reveals that PHEVs release just one-fifth less CO₂ than conventional petrol and diesel cars, according to research conducted by a non-profit organization. That differs sharply with laboratory estimates, which suggested a three-quarters decrease in emissions.

Analysts examined information from in-vehicle fuel consumption meters of 800,000 vehicles registered in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while official figures are decreasing,” said a senior analyst participating in the report. “That gap is widening and poses a significant problem. Consequently, PHEVs pollute almost as heavily as petrol cars.”

Primary Reasons Behind the Emissions Gap

Analysts attributed most of the gap to overestimates of the “utility factor” – the percentage of miles travelled in electric mode relative to total distance. The team found that only a quarter of travel was done in electric mode, while lab estimates suggested 84%.

Additionally, when running in electric mode, pollution levels were well above official projections. This happened because electric motors were not strong enough to operate alone, resulting to combustion motors using fossil fuels for nearly a third of the distance covered in EV mode.

Policy and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output enabled four large carmaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ standards.

Additionally, owners of PHEVs would spend about €500 more per year in operating costs than would be estimated under laboratory tests.

“The bold claims that manufacturers like to make about their PHEV vehicles are obviously way off the truth,” commented a transport analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly better than standard petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Political Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been brought back into policy debates as carmakers have pressed the European Union to weaken CO₂ standards. A planned ban on new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and resistance from EU countries with large automotive industries.

Several high-level politicians have suggested plug-in hybrids as a possible “compromise” solution to include in the regulation.

One external energy economics specialist, who was unaffiliated with the study, described the report a “very useful contribution” after a long period in which segments of the car industry claimed there was too little data to accurately evaluate real-world CO2 output.

“The results demonstrate, without question, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel vehicles,” the expert stated. “All regulatory adjustments concerning PHEVs should be made with utmost caution and considering this data.”