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PHEVs produce nearly five times greater global warming emissions than official figures indicate, as per a new analysis.

Growing Gap Between Official and Actual Emissions

Data shows that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a non-profit group. That contrasts significantly with lab estimates, which assumed a 75% decrease in emissions.

Researchers studied information from onboard fuel consumption monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” said a lead analyst involved in the report. “This gap is growing and poses a serious problem. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Key Factors Driving the Discrepancy

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

Even, when operating in electric mode, emission levels were significantly higher than official projections. This occurred because electric motors were not strong enough to function independently, resulting to engines burning fossil fuels for almost a third of the distance completed in electric mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV emissions allowed four large carmaker companies to escape more than €5bn in fines from 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ targets.

Additionally, owners of PHEVs would pay about €500 extra per year in operating costs than would be estimated under lab conditions.

“The bold statements that manufacturers often promote about their PHEV cars are clearly way off the truth,” commented a automotive expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have recently been brought again into political discussions as automakers have pressed the European Union to relax CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced intense pressure from the car sector and opposition from EU countries with large car industries.

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

One independent energy policy specialist, who was unaffiliated with the research, described the report a “very useful contribution” after years in which parts of the automotive sector argued there was insufficient data to accurately assess actual emissions.

“These findings show, without question, that the gap between lab and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel vehicles,” the expert said. “Any regulatory adjustments regarding PHEVs should be made with extreme care and in the light of that data.”