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Plug-in hybrid cars emit almost 5x more planet-heating pollution than official figures show, as per a recent analysis.

Widening Discrepancy Between Official and Real-World Emissions

Statistics shows that PHEVs release just one-fifth lower CO₂ than conventional gas and diesel cars, based on analysis carried out by a advocacy group. This contrasts significantly with laboratory tests, which assumed a 75% reduction in pollution.

Analysts studied data from in-vehicle energy use meters of 800,000 vehicles sold in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are falling,” stated a senior analyst involved in the study. “This discrepancy is widening and creates a serious issue. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “electric driving share” – the percentage of kilometers driven in battery mode compared to total distance. The team determined that just a quarter of travel was completed in electric mode, whereas official estimates assumed over four-fifths.

Additionally, when operating in electric mode, pollution levels were significantly higher than official estimates. This happened because EV motors were insufficiently powerful enough to function independently, leading to combustion motors using fossil fuels for almost one-third of the travel covered in EV mode.

Policy and Economic Implications

According to estimates, the lowballing of PHEV emissions enabled several major carmaker companies to avoid more than €5bn in penalties from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Additionally, owners of PHEVs could pay about €500 more annually in operating costs than is assumed under lab tests.

“The strong claims that automakers like to make about their PHEV vehicles are clearly far from the mark,” stated a automotive expert. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving costs. In reality, PHEVs are little better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have recently been drawn back into policy discussions as carmakers have pressed the EU to relax CO₂ standards. A proposed prohibition on new combustion engine cars in 2035 has faced intense pressure from the car sector and resistance from member states with large car industries.

Some high-level officials have proposed plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

One external energy policy specialist, who was not involved with the research, called the report a “very useful contribution” after years in which segments of the automotive industry claimed there was too little information to accurately assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ output is much, much larger than for gasoline or diesel vehicles,” the expert said. “Any policy adjustments concerning PHEVs should be made with utmost care and considering this data.”