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Plug-in hybrid cars produce almost 5x greater planet-heating emissions than lab-reported data indicate, according to a new report.

Growing Discrepancy Between Lab and Real-World Emissions

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel cars, according to analysis conducted by a advocacy organization. That differs significantly with lab estimates, which suggested a 75% reduction in emissions.

Analysts studied information from in-vehicle fuel consumption meters of 800,000 vehicles registered in Europe between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” stated a senior analyst involved in the study. “That discrepancy is growing and creates a serious problem. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Primary Reasons Behind the Emissions Gap

Analysts attributed most of the difference to overestimates of the “electric driving share” – the percentage of miles travelled in electric power compared to overall distance. They found that just a quarter of travel was done in EV mode, while official assumptions assumed over four-fifths.

Even, when operating in EV mode, pollution amounts were significantly higher than official estimates. This occurred because electric motors were not strong sufficient to function alone, resulting to combustion motors using fossil fuels for nearly one-third of the travel covered in EV mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV emissions allowed four large automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 extra per year in running costs than would be estimated under lab conditions.

“The strong claims that automakers like to make about their PHEV vehicles are obviously way off the truth,” stated a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Political Discussion and Industry Lobbying

Hybrid vehicles have lately been brought back into political debates as automakers have pressed the EU to relax CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced intense pressure from the automotive sector and opposition from member states with significant automotive manufacturing.

Some senior politicians have proposed plug-in hybrids as a possible “compromise” option to introduce in the regulation.

One external energy policy expert, who was not involved with the study, described the report a “very useful addition” after years in which segments of the car sector claimed there was insufficient data to properly assess real-world CO2 output.

“These findings show, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional vehicles,” they said. “All policy adjustments regarding PHEVs should be implemented with extreme care and considering this evidence.”