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Plug-in hybrid electric vehicles release almost five times more planet-heating pollution than lab-reported figures indicate, as per a recent report.

Widening Discrepancy Between Lab and Actual CO2 Output

Data reveals that PHEVs release just 19% less CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a advocacy organization. This differs sharply with lab tests, which suggested a 75% decrease in emissions.

Analysts examined data from in-vehicle energy use meters of eight hundred thousand cars sold in Europe from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from 3.5 times in 2021.

“Actual emissions are increasing, while lab-reported emissions are falling,” stated a senior researcher participating in the study. “That discrepancy is widening and poses a significant problem. As a result, PHEVs emit nearly as heavily as gasoline cars.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers driven in electric mode compared to overall distance. The team determined that only a quarter of driving was completed in electric mode, while lab estimates suggested 84%.

Even, when operating in electric mode, emission levels were significantly higher than official estimates. This occurred because EV motors were insufficiently powerful enough to operate alone, leading to combustion motors using gasoline for nearly a third of the distance covered in electric mode.

Regulatory and Financial Implications

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

Furthermore, drivers of PHEVs could spend about €500 extra per year in running expenses than would be assumed under lab tests.

“The strong statements that manufacturers like to make about their PHEV cars are clearly way off the mark,” stated a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting money. In reality, PHEVs are little better than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating expenses.”

Policy Debate and Automotive Pressure

Plug-in hybrid cars have recently been drawn back into policy discussions as automakers have lobbied the EU to weaken CO₂ standards. A planned ban on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the car industry and opposition from member states with large automotive manufacturing.

Some high-level officials have suggested plug-in hybrids as a possible “flexibility” solution to introduce in the regulation.

One external energy economics specialist, who was not involved with the study, called the analysis a “highly valuable addition” after a long period in which segments of the automotive industry claimed there was too little data to properly assess actual CO2 output.

“These findings demonstrate, beyond any doubt, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” they said. “Any regulatory changes concerning PHEVs should be implemented with extreme care and considering that data.”