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Plug-in hybrid electric vehicles produce almost 5x greater planet-heating emissions than official figures indicate, according to a recent analysis.

Widening Gap Between Official and Real-World CO2 Output

Statistics shows that PHEVs emit only one-fifth lower CO₂ than conventional gas and diesel cars, according to analysis conducted by a advocacy organization. This differs significantly with lab estimates, which suggested a three-quarters decrease in pollution.

Researchers examined data from in-vehicle energy use meters of eight hundred thousand cars sold in the EU between 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than official estimates, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” said a lead analyst participating in the report. “This discrepancy is widening and poses a significant issue. As a result, PHEVs emit nearly as much as petrol vehicles.”

Primary Factors Behind the Discrepancy

Analysts linked most of the difference to overestimates of the “utility factor” – the ratio of miles travelled in electric power relative to total mileage. They determined that just 27% of driving was done in electric mode, while official estimates suggested over four-fifths.

Even, when running in electric mode, emission levels were well above lab estimates. That happened because electric motors were insufficiently powerful enough to operate alone, leading to combustion motors using fossil fuels for almost one-third of the distance covered in electric mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV emissions enabled several major carmaker companies to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 more per year in operating costs than would be assumed under lab conditions.

“The bold claims that automakers often promote about their plug-in hybrid cars are clearly way off the mark,” commented a automotive expert. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Pressure

Hybrid cars have recently been drawn back into policy debates as automakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on new internal combustion cars in 2035 has faced intense lobbying from the car industry and opposition from member states with significant automotive manufacturing.

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

An independent energy economics expert, who was not involved with the research, called the report a “highly valuable addition” after a long period in which parts of the automotive industry claimed there was insufficient data to properly assess real-world CO2 output.

“These findings show, without question, that the difference between lab and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or diesel cars,” the expert stated. “Any policy adjustments regarding PHEVs should be made with utmost care and in the light of that evidence.”