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Plug-in hybrid electric vehicles emit almost 5x more global warming emissions than lab-reported data indicate, as per a new analysis.

Growing Gap Between Official and Actual CO2 Output

Data reveals that PHEVs emit just one-fifth lower CO₂ than conventional gas and diesel vehicles, according to analysis conducted by a non-profit group. This differs significantly with laboratory estimates, which assumed a 75% decrease in pollution.

Researchers examined information from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while official figures are falling,” stated a lead researcher involved in the study. “This discrepancy is widening and creates a significant issue. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Reasons Behind the Discrepancy

Researchers linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of miles travelled in battery mode relative to total distance. The team determined that only a quarter of driving was completed in electric mode, whereas lab assumptions suggested 84%.

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

Policy and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output enabled four large automaker groups to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay about €500 extra per year in operating expenses than is assumed under lab tests.

“The strong statements that automakers often promote about their PHEV cars are clearly far from the mark,” commented a transport expert. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are little improved than regular petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Political Discussion and Industry Lobbying

Hybrid cars have recently been drawn back into policy discussions as automakers have pressed the European Union to relax CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced intense pressure from the car industry and resistance from member states with significant car manufacturing.

Some high-level politicians have proposed PHEVs as a possible “compromise” solution to introduce in the regulation.

One independent energy policy specialist, who was unaffiliated with the study, described the report a “very useful addition” after a long period in which parts of the car sector argued there was too little information to accurately assess real-world emissions.

“These findings demonstrate, without question, that the gap in official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or conventional cars,” they stated. “All policy changes regarding PHEVs should be made with extreme caution and in the light of that data.”