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PHEVs release almost five times greater planet-heating emissions than lab-reported data indicate, according to a new report.

Growing Discrepancy Between Official and Real-World Emissions

Data reveals that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel vehicles, based on analysis carried out by a non-profit group. That differs significantly with laboratory estimates, which assumed a three-quarters reduction in pollution.

Analysts examined information from in-vehicle fuel consumption monitors of 800,000 vehicles sold in Europe between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” said a lead analyst participating in the report. “This discrepancy is widening and poses a significant issue. Consequently, PHEVs pollute almost as heavily as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of miles driven in electric power compared to total distance. The team determined that just a quarter of travel was done in electric mode, whereas official assumptions assumed over four-fifths.

Even, when running in EV mode, pollution amounts were significantly higher than official projections. That occurred because EV motors were insufficiently powerful sufficient to operate independently, leading to engines using fossil fuels for nearly one-third of the distance completed in electric mode.

Regulatory and Economic Implications

Based on calculations, the underestimation of PHEV CO2 output allowed four large carmaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend approximately €500 more per year in running costs than would be estimated under laboratory conditions.

“The strong claims that manufacturers often promote about their PHEV vehicles are obviously far from the truth,” commented a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the planet and cutting money. Actually, PHEVs are little better than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Policy Discussion and Industry Pressure

Hybrid cars have lately been brought back into political debates as carmakers have lobbied the EU to weaken CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with large automotive manufacturing.

Several senior politicians have suggested plug-in hybrids as a possible “compromise” solution to include in the legislation.

One external energy policy expert, who was not involved with the study, described the analysis a “very useful addition” after a long period in which segments of the automotive sector argued there was too little data to properly evaluate actual CO2 output.

“The results demonstrate, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or diesel cars,” the expert stated. “Any policy changes regarding PHEVs should be implemented with extreme caution and considering this data.”