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PHEVs produce nearly 5x greater planet-heating pollution than lab-reported figures show, according to a recent analysis.

Widening Gap Between Official and Actual Emissions

Statistics shows that PHEVs emit just 19% less CO₂ than conventional gas and diesel vehicles, based on research carried out by a advocacy organization. That differs sharply with laboratory estimates, which assumed a 75% decrease in pollution.

Analysts studied information from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are falling,” said a senior researcher participating in the study. “That discrepancy is growing and creates a serious problem. Consequently, PHEVs emit nearly as heavily as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers driven in battery power compared to total distance. The team determined that only 27% of driving was done in EV mode, whereas lab assumptions assumed over four-fifths.

Even, when running in EV mode, emission amounts were well above lab projections. That occurred because EV motors were insufficiently powerful enough to function alone, leading to combustion motors burning gasoline for nearly a third of the distance covered in EV mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled four major automaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would pay about €500 extra per year in running expenses than would be assumed under lab tests.

“The strong statements that manufacturers often promote about their PHEV vehicles are obviously way off the mark,” commented a automotive expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of fuel use, CO₂ production, and running costs.”

Political Debate and Industry Lobbying

Hybrid cars have lately been brought back into policy discussions as carmakers have pressed the EU to weaken CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with large automotive industries.

Several senior officials have proposed PHEVs as a possible “compromise” option to introduce in the legislation.

One external energy policy expert, who was not involved with the research, called the report a “highly valuable contribution” after a long period in which parts of the car industry claimed there was insufficient information to accurately evaluate real-world CO2 output.

“These findings demonstrate, without question, that the gap in official and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or diesel cars,” the expert said. “Any regulatory changes regarding PHEVs should be made with extreme care and in the light of that evidence.”