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PHEVs emit nearly 5x more global warming emissions than lab-reported data indicate, according to a recent analysis.

Growing Gap Between Lab and Actual CO2 Output

Data reveals that PHEVs release only one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on research conducted by a advocacy group. This contrasts sharply with lab tests, which assumed a 75% decrease in emissions.

Analysts examined information from in-vehicle fuel consumption meters of 800,000 cars sold in the EU from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official figures, up from three and a half times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” said a senior researcher participating in the study. “This discrepancy is growing and poses a significant problem. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Key Factors Driving the Emissions Gap

Analysts linked most of the gap to inflated estimates of the “utility factor” – the ratio of miles driven in electric power compared to total mileage. They found that only a quarter of travel was completed in electric mode, whereas lab assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution amounts were well above official projections. This occurred because EV motors were insufficiently powerful enough to function alone, leading to combustion motors using gasoline for almost one-third of the distance covered in electric mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output allowed several large carmaker companies to escape over €5bn in penalties from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay about €500 more annually in running expenses than is assumed under lab tests.

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the mark,” stated a transport analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little improved than standard gas and diesel cars in terms of energy consumption, CO₂ emissions, and running costs.”

Political Debate and Industry Pressure

Plug-in hybrid cars have lately been brought again into political debates as automakers have lobbied the European Union to relax CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced heavy pressure from the car industry and resistance from EU countries with significant car manufacturing.

Several high-level officials have suggested PHEVs as a possible “flexibility” solution to introduce in the legislation.

An independent energy economics expert, who was not involved with the research, called the analysis a “highly valuable contribution” after a long period in which segments of the automotive sector claimed there was too little information to accurately assess actual emissions.

“These findings demonstrate, without question, that the difference between official and actual PHEV energy use and CO₂ output is much, much larger than for petrol or conventional cars,” the expert stated. “Any regulatory adjustments concerning PHEVs should be implemented with utmost care and in the light of that data.”