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PHEVs emit almost five times more planet-heating emissions than official data indicate, according to a recent analysis.

Widening Gap In Lab and Real-World CO2 Output

Statistics shows that PHEVs emit only one-fifth less CO₂ than conventional petrol and diesel cars, based on analysis carried out by a advocacy organization. That differs significantly with lab tests, which assumed a three-quarters decrease in pollution.

Analysts examined data from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in Europe from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” said a lead analyst participating in the report. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs pollute nearly as much as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Researchers linked most of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in electric power relative to total distance. They found that just 27% of travel was done in electric mode, while lab assumptions suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were significantly higher than official projections. That happened because EV motors were insufficiently powerful enough to function alone, leading to engines using gasoline for almost a third of the travel completed in EV mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed several major automaker companies to escape more than €5bn in fines between 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs could pay about €500 extra annually in operating costs than would be assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the mark,” commented a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and cutting money. In reality, PHEVs are only slightly improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Political Discussion and Automotive Pressure

Hybrid cars have recently been brought back into policy debates as automakers have pressed the EU to weaken CO₂ standards. A planned ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the car sector and opposition from EU countries with significant car manufacturing.

Some high-level officials have suggested plug-in hybrids as a potential “flexibility” solution to include in the legislation.

An external energy economics expert, who was not involved with the research, described the report a “highly valuable addition” after a long period in which segments of the car sector claimed there was insufficient data to accurately assess real-world emissions.

“These findings show, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or conventional cars,” they stated. “Any regulatory adjustments concerning PHEVs should be implemented with extreme caution and in the light of that evidence.”