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Plug-in hybrid cars release nearly five times more planet-heating pollution than lab-reported figures indicate, as per a recent analysis.

Widening Gap In Lab and Real-World Emissions

Statistics shows that PHEVs release only one-fifth less CO₂ than conventional gas and diesel vehicles, based on analysis conducted by a non-profit group. That contrasts sharply with laboratory tests, which assumed a 75% decrease in emissions.

Researchers examined data from in-vehicle energy use meters of eight hundred thousand cars sold in the EU between 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported figures are falling,” said a senior analyst involved in the report. “That discrepancy is growing and creates a significant issue. Consequently, PHEVs emit nearly as much as gasoline cars.”

Primary Factors Driving the Discrepancy

Researchers linked the majority of the gap to overestimates of the “utility factor” – the percentage of miles travelled in battery mode relative to overall mileage. They determined that only 27% of travel was completed in EV mode, while lab assumptions suggested over four-fifths.

Even, when running in EV mode, pollution levels were well above official projections. This happened because electric motors were not strong enough to operate alone, leading to combustion motors using gasoline for almost one-third of the travel covered in EV mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV CO2 output allowed four large carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would pay approximately €500 extra per year in running costs than would be assumed under lab tests.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are obviously far from the mark,” stated a automotive analyst. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel use, CO₂ production, and operating costs.”

Political Debate and Industry Lobbying

Hybrid vehicles have lately been brought back into political debates as carmakers have pressed the EU to weaken CO₂ targets. A planned prohibition on new internal combustion cars in 2035 has faced intense pressure from the car industry and opposition from EU countries with significant automotive manufacturing.

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

An independent energy policy expert, who was not involved with the study, called the analysis a “very useful contribution” after years in which parts of the automotive sector argued there was too little data to accurately assess real-world emissions.

“The results show, without question, that the gap in official and actual PHEV energy use and CO₂ emissions is much, much greater than for gasoline or diesel cars,” they stated. “Any regulatory adjustments regarding PHEVs should be made with extreme care and in the light of this data.”