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PHEVs release almost 5x greater planet-heating pollution than official data indicate, according to a new analysis.

Growing Gap Between Lab and Actual Emissions

Statistics reveals that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel vehicles, based on research conducted by a advocacy group. This contrasts significantly with laboratory estimates, which suggested a 75% decrease in pollution.

Analysts studied information from in-vehicle energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” stated a senior analyst involved in the study. “That gap is growing and poses a significant problem. As a result, PHEVs emit almost as heavily as gasoline cars.”

Primary Factors Behind the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in electric mode compared to total mileage. They found that only a quarter of driving was done in electric mode, while official estimates suggested 84%.

Additionally, when running in EV mode, pollution levels were significantly higher than lab projections. That occurred because EV motors were insufficiently powerful enough to operate independently, leading to combustion motors using fossil fuels for nearly one-third of the distance covered in EV mode.

Policy and Economic Consequences

According to estimates, the lowballing of PHEV CO2 output enabled several major automaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs could pay approximately €500 more per year in operating expenses than is assumed under lab tests.

“The strong claims that automakers like to make about their PHEV cars are obviously far from the mark,” commented a automotive analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel use, CO₂ production, and running costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have lately been brought back into political discussions as automakers have pressed the European Union to weaken CO₂ standards. A proposed ban on new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and resistance from member states with significant automotive manufacturing.

Some high-level officials have suggested plug-in hybrids as a possible “flexibility” option to include in the regulation.

One external energy policy specialist, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after years in which segments of the automotive industry claimed there was insufficient data to properly evaluate real-world emissions.

“These findings show, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for gasoline or conventional vehicles,” the expert stated. “All policy adjustments regarding PHEVs should be made with utmost care and in the light of this data.”