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PHEVs release almost five times more global warming emissions than official data indicate, according to a recent analysis.

Widening Discrepancy Between Lab and Actual Emissions

Data reveals that PHEVs emit only 19% less CO₂ than traditional petrol and diesel cars, based on research carried out by a advocacy organization. This differs sharply with lab estimates, which assumed a three-quarters decrease in emissions.

Researchers examined information from in-vehicle energy use monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. The team discovered that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, up from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” stated a lead researcher involved in the study. “That gap is widening and creates a serious issue. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Key Factors Driving the Emissions Gap

Analysts attributed the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery power relative to overall distance. The team determined that just 27% of driving was completed in electric mode, while official estimates suggested 84%.

Even, when operating in EV mode, pollution amounts were well above official estimates. That occurred because electric motors were not strong sufficient to operate alone, leading to combustion motors using fossil fuels for almost a third of the distance covered in electric mode.

Regulatory and Financial Implications

Based on estimates, the lowballing of PHEV CO2 output allowed four large carmaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ targets.

Additionally, owners of PHEVs could spend about €500 extra per year in running costs than would be assumed under laboratory conditions.

“The strong claims that manufacturers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Political Debate and Automotive Lobbying

Hybrid vehicles have lately been drawn again into policy debates as automakers have pressed the European Union to relax CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive industry and resistance from member states with large car manufacturing.

Some senior officials have proposed plug-in hybrids as a potential “flexibility” solution to include in the legislation.

An independent energy economics expert, who was not involved with the study, called the report a “highly valuable addition” after years in which segments of the automotive industry argued there was too little information to accurately assess actual CO2 output.

“The results show, without question, that the difference between lab and real-world PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel cars,” the expert stated. “Any policy changes regarding PHEVs should be made with extreme care and in the light of that evidence.”