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Plug-in hybrid cars produce almost 5x greater planet-heating emissions than lab-reported data indicate, as per a recent report.

Widening Gap In Official and Real-World CO2 Output

Data shows that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel vehicles, based on research carried out by a non-profit group. This differs significantly with lab estimates, which suggested a 75% reduction in pollution.

Analysts studied data from in-vehicle fuel consumption monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are rising, while official emissions are falling,” said a lead analyst participating in the report. “That gap is widening and creates a significant issue. Consequently, PHEVs pollute almost as much as gasoline cars.”

Primary Factors Behind the Discrepancy

Researchers linked most of the gap to inflated estimates of the “electric driving share” – the ratio of miles driven in battery mode compared to overall mileage. The team found that only 27% of driving was completed in EV mode, whereas lab assumptions assumed 84%.

Additionally, when running in EV mode, emission levels were well above official projections. That occurred because electric motors were not strong enough to function alone, resulting to engines using gasoline for almost a third of the travel completed in electric mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV CO2 output allowed several major carmaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 extra annually in operating costs than is estimated under laboratory conditions.

“The strong claims that manufacturers like to make about their PHEV vehicles are obviously far from the truth,” commented a automotive expert. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Political Debate and Automotive Pressure

Hybrid vehicles have recently been drawn again into political discussions as automakers have lobbied the European Union to relax CO₂ standards. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and resistance from member states with significant car industries.

Some high-level officials have suggested PHEVs as a possible “compromise” option to introduce in the regulation.

An external energy economics expert, who was unaffiliated with the study, called the report a “very useful contribution” after years in which segments of the automotive industry claimed there was too little information to properly assess real-world emissions.

“The results demonstrate, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or diesel vehicles,” the expert stated. “All regulatory changes regarding PHEVs should be implemented with extreme caution and in the light of this evidence.”