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Plug-in hybrid electric vehicles emit nearly five times more planet-heating emissions than lab-reported data indicate, as per a recent analysis.

Growing Discrepancy In Official and Actual Emissions

Statistics shows that PHEVs emit only 19% less CO₂ than traditional petrol and diesel vehicles, based on research carried out by a non-profit group. That differs sharply with lab tests, which assumed a 75% reduction in emissions.

Analysts studied data from onboard fuel consumption monitors of 800,000 cars registered in Europe between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported figures are falling,” said a lead researcher participating in the report. “This discrepancy is growing and poses a significant problem. As a result, PHEVs pollute nearly as heavily as petrol cars.”

Key Factors Behind the Emissions Gap

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles driven in battery power relative to total mileage. The team determined that only 27% of travel was done in electric mode, whereas official estimates assumed over four-fifths.

Even, when operating in EV mode, pollution amounts were significantly higher than lab estimates. This happened because electric motors were not strong sufficient to function independently, resulting to engines using gasoline for almost one-third of the distance completed in EV mode.

Regulatory and Economic Implications

Based on calculations, the lowballing of PHEV emissions allowed four large carmaker companies to escape over €5bn in fines between 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ standards.

Additionally, drivers of PHEVs would pay about €500 extra annually in running expenses than would be assumed under lab tests.

“The strong statements that automakers like to make about their plug-in hybrid cars are obviously far from the mark,” commented a transport expert. “Buyers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are only slightly improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and operating costs.”

Political Debate and Industry Pressure

Hybrid vehicles have recently been drawn again into policy discussions as carmakers have lobbied the European Union to relax CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the car sector and opposition from member states with significant car industries.

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

An external energy policy expert, who was not involved with the study, called the report a “very useful contribution” after a long period in which parts of the automotive sector claimed there was insufficient information to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is much, much larger than for petrol or diesel vehicles,” they said. “All policy adjustments regarding PHEVs should be made with utmost care and considering this data.”