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Plug-in hybrid electric vehicles release nearly five times more planet-heating emissions than official figures show, according to a recent report.

Widening Gap Between Lab and Actual Emissions

Statistics reveals that PHEVs release just 19% less CO₂ than conventional petrol and diesel cars, based on analysis conducted by a non-profit group. This differs sharply with lab estimates, which assumed a three-quarters reduction in pollution.

Researchers examined information from onboard energy use meters of eight hundred thousand cars sold in Europe between 2021 and 2023. They found that actual CO₂ output 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 increasing, while lab-reported emissions are falling,” stated a senior analyst participating in the study. “This gap is widening and poses a serious problem. As a result, PHEVs pollute nearly as heavily as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric power relative to total distance. The team determined that just 27% of driving was done in EV mode, whereas lab estimates suggested 84%.

Additionally, when running in electric mode, pollution levels were well above official projections. This occurred because electric motors were not strong enough to function independently, resulting to engines using fossil fuels for almost a third of the distance completed in electric mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output allowed several major carmaker groups to avoid more than €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

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

“The bold statements that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” commented a automotive analyst. “Buyers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are little better than regular petrol and diesel vehicles in terms of energy use, CO₂ production, and operating expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have recently been brought back into political discussions as automakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the car sector and resistance from member states with large car manufacturing.

Some senior politicians have suggested plug-in hybrids as a potential “flexibility” option to include in the regulation.

One external energy policy specialist, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after a long period in which segments of the car industry claimed there was insufficient data to properly evaluate actual emissions.

“These findings show, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or conventional vehicles,” the expert stated. “All regulatory adjustments concerning PHEVs should be made with utmost care and considering that evidence.”