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Plug-in hybrid electric vehicles emit almost 5x greater global warming pollution than lab-reported data indicate, as per a recent report.

Widening Discrepancy In Official and Real-World CO2 Output

Statistics reveals that PHEVs release just 19% lower CO₂ than conventional gas and diesel vehicles, based on research conducted by a advocacy group. This differs sharply with lab estimates, which assumed a 75% decrease in pollution.

Researchers studied data from onboard fuel consumption meters of 800,000 vehicles registered in the EU between 2021 and 2023. They discovered that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official figures, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while official figures are decreasing,” said a senior analyst participating in the study. “That gap is widening and poses a serious issue. Consequently, PHEVs pollute almost as much as petrol vehicles.”

Key Reasons Behind the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in electric power compared to overall distance. They determined that just a quarter of driving was done in electric mode, while official estimates suggested 84%.

Additionally, when operating in EV mode, pollution amounts were significantly higher than lab projections. This occurred because EV motors were insufficiently powerful enough to operate independently, leading to engines burning fossil fuels for nearly one-third of the travel completed in electric mode.

Policy and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output enabled several large carmaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 more annually in running expenses than would be assumed under laboratory tests.

“The bold statements that automakers often promote about their plug-in hybrid vehicles are obviously far from the mark,” stated a transport expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the environment and cutting money. Actually, PHEVs are little improved than regular gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Policy Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought again into political discussions as carmakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the automotive industry and resistance from EU countries with large car industries.

Some senior politicians have proposed plug-in hybrids as a potential “compromise” solution to introduce in the legislation.

One external energy economics specialist, who was unaffiliated with the study, described the report a “very useful contribution” after years in which parts of the car sector argued there was insufficient information to accurately evaluate actual emissions.

“These findings demonstrate, beyond any doubt, that the gap between official and actual PHEV fuel consumption and CO₂ output is much, much greater than for petrol or conventional vehicles,” they said. “All policy changes concerning PHEVs should be made with utmost care and considering that evidence.”