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Plug-in hybrid electric vehicles emit almost 5x more planet-heating emissions than lab-reported figures indicate, according to a recent report.

Widening Gap Between Lab and Real-World Emissions

Statistics reveals that PHEVs emit only one-fifth lower CO₂ than conventional petrol and diesel cars, based on analysis conducted by a non-profit group. This contrasts significantly with laboratory tests, which suggested a three-quarters decrease in emissions.

Researchers studied information from onboard fuel consumption monitors of 800,000 vehicles registered in the EU between 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while official figures are decreasing,” stated a lead analyst participating in the study. “This gap is widening and poses a significant issue. As a result, PHEVs emit nearly as much as petrol cars.”

Primary Reasons Driving the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery power compared to total mileage. They found that only a quarter of driving was completed in electric mode, while lab estimates assumed 84%.

Even, when operating in electric mode, emission levels were significantly higher than official estimates. This happened because electric motors were not strong sufficient to function independently, resulting to combustion motors burning gasoline for nearly one-third of the travel completed in electric mode.

Policy and Economic Implications

According to estimates, the lowballing of PHEV emissions enabled several large carmaker groups to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ targets.

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

“The strong claims that automakers often promote about their PHEV cars are clearly way off the mark,” commented a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Political Discussion and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn back into political debates as automakers have lobbied the European Union to relax CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced intense pressure from the automotive sector and opposition from member states with large car manufacturing.

Several senior officials have proposed plug-in hybrids as a possible “compromise” option to introduce in the legislation.

One independent energy policy expert, who was unaffiliated with the research, called the analysis a “highly valuable addition” after years in which segments of the automotive sector claimed there was insufficient data to accurately assess real-world CO2 output.

“The results demonstrate, without question, that the gap in lab and real-world PHEV energy use and CO₂ output is significantly greater than for petrol or diesel cars,” the expert stated. “Any regulatory adjustments regarding PHEVs should be implemented with extreme care and considering this evidence.”