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PHEVs emit almost 5x more global warming emissions than lab-reported figures indicate, as per a new analysis.

Widening Discrepancy In Lab and Real-World Emissions

Data reveals that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel cars, based on analysis conducted by a advocacy group. That contrasts sharply with laboratory tests, which suggested a 75% reduction in emissions.

Researchers studied information from onboard fuel consumption meters of 800,000 cars registered in Europe from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while official figures are falling,” said a senior analyst involved in the study. “That gap is growing and poses a significant problem. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Key Factors Driving the Emissions Gap

Analysts attributed most of the gap to overestimates of the “electric driving share” – the percentage of miles travelled in electric mode compared to overall distance. They determined that only 27% of driving was completed in electric mode, while lab estimates suggested 84%.

Additionally, when operating in EV mode, emission levels were significantly higher than lab estimates. That occurred because EV motors were not strong sufficient to operate independently, leading to engines using gasoline for nearly a third of the distance completed in electric mode.

Regulatory and Financial Consequences

According to estimates, the underestimation of PHEV CO2 output allowed four major automaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ standards.

Additionally, drivers of PHEVs could spend about €500 extra per year in running expenses than would be estimated under lab conditions.

“The bold claims that automakers like to make about their plug-in hybrid vehicles are clearly way off the mark,” commented a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and saving costs. Actually, PHEVs are little better than regular gas and diesel vehicles in terms of fuel use, CO₂ production, and running costs.”

Political Debate and Automotive Lobbying

Hybrid vehicles have recently been drawn again into policy debates as carmakers have pressed the EU to relax CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with large automotive industries.

Several high-level officials have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

One independent energy policy expert, who was not involved with the study, described the analysis a “highly valuable contribution” after a long period in which parts of the automotive industry claimed there was insufficient data to accurately evaluate actual CO2 output.

“The results show, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ emissions is significantly greater than for petrol or conventional vehicles,” they stated. “Any regulatory adjustments regarding PHEVs should be implemented with extreme care and in the light of that data.”