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Plug-in hybrid electric vehicles emit nearly five times more planet-heating emissions than official data show, according to a recent analysis.

Widening Gap Between Official and Real-World CO2 Output

Statistics shows that PHEVs release just 19% lower CO₂ than traditional petrol and diesel vehicles, according to analysis conducted by a non-profit organization. This contrasts significantly with laboratory estimates, which assumed a 75% decrease in pollution.

Analysts studied information from in-vehicle energy use monitors of 800,000 cars sold in the EU between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab figures, increased from three and a half times in 2021.

“Actual CO2 output are rising, while official figures are falling,” stated a senior researcher participating in the report. “That discrepancy is growing and creates a serious issue. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of miles driven in battery power relative to total mileage. They determined that only 27% of driving was done in electric mode, while official assumptions assumed over four-fifths.

Even, when operating in electric mode, pollution levels were significantly higher than lab projections. This occurred because electric motors were not strong enough to operate alone, leading to combustion motors using fossil fuels for nearly one-third of the travel completed in electric mode.

Policy and Economic Implications

Based on estimates, the lowballing of PHEV CO2 output allowed several major carmaker companies to avoid more than €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more annually in operating costs than is assumed under laboratory conditions.

“The bold statements that manufacturers like to make about their PHEV vehicles are obviously far from the truth,” stated a automotive analyst. “Consumers are being misled into believing that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are little improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and running expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have recently been brought again into political debates as carmakers have pressed the EU to relax CO₂ targets. A planned ban on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive sector and resistance from member states with significant automotive manufacturing.

Some senior officials have suggested plug-in hybrids as a possible “flexibility” solution to introduce in the legislation.

An external energy economics specialist, who was unaffiliated with the research, called the analysis a “very useful addition” after years in which parts of the car sector argued there was insufficient data to accurately assess actual emissions.

“The results show, beyond any doubt, that the gap in lab and real-world PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel cars,” the expert said. “Any policy changes regarding PHEVs should be made with extreme caution and considering this data.”