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PHEVs release nearly five times greater planet-heating emissions than official data show, as per a recent analysis.

Growing Discrepancy Between Official and Actual Emissions

Data reveals that PHEVs emit only 19% lower CO₂ than conventional petrol and diesel vehicles, according to analysis carried out by a non-profit organization. That contrasts significantly with laboratory estimates, which assumed a 75% reduction in pollution.

Researchers examined information from onboard energy use monitors of 800,000 vehicles sold in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are falling,” said a senior researcher participating in the study. “This gap is widening and poses a serious issue. Consequently, PHEVs emit nearly as much as gasoline vehicles.”

Key Factors Behind the Emissions Gap

Researchers attributed the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in battery power compared to overall distance. The team determined that just a quarter of driving was completed in electric mode, whereas official estimates suggested 84%.

Even, when operating in electric mode, emission levels were well above official projections. This happened because electric motors were insufficiently powerful enough to operate alone, leading to engines using fossil fuels for almost a third of the travel completed in electric mode.

Regulatory and Financial Implications

According to calculations, the lowballing of PHEV CO2 output allowed several major carmaker groups to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ targets.

Additionally, owners of PHEVs would pay approximately €500 more per year in operating expenses than would be estimated under laboratory tests.

“The bold claims that manufacturers like to make about their plug-in hybrid cars are clearly way off the mark,” stated a automotive expert. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating costs.”

Political Debate and Industry Pressure

Plug-in hybrid vehicles have recently been drawn again into political discussions as carmakers have lobbied the EU to weaken CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with large car industries.

Several senior officials have suggested PHEVs as a possible “compromise” solution to include in the legislation.

One independent energy policy specialist, who was unaffiliated with the research, described the analysis a “very useful contribution” after years in which parts of the automotive industry claimed there was insufficient data to properly evaluate real-world emissions.

“The results show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel cars,” the expert stated. “All policy adjustments concerning PHEVs should be implemented with extreme caution and considering this evidence.”