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Plug-in hybrid cars release nearly five times greater planet-heating emissions than official figures show, as per a recent analysis.

Growing Discrepancy Between Lab and Real-World CO2 Output

Statistics reveals that PHEVs emit only one-fifth lower CO₂ than traditional gas and diesel vehicles, based on research carried out by a non-profit organization. That differs sharply with laboratory estimates, which assumed a three-quarters decrease in pollution.

Analysts examined data from in-vehicle fuel consumption meters of 800,000 cars sold in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, up from three and a half times in 2021.

“Actual emissions are rising, while official emissions are falling,” said a senior analyst participating in the study. “This discrepancy is widening and creates a significant problem. As a result, PHEVs pollute almost as heavily as petrol cars.”

Primary Reasons Driving the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the percentage of miles driven in electric mode relative to overall mileage. They determined that only 27% of travel was done in EV mode, while official estimates assumed over four-fifths.

Even, when operating in EV mode, emission amounts were well above official estimates. That happened because EV motors were insufficiently powerful enough to function alone, resulting to engines using fossil fuels for almost a third of the travel covered in EV mode.

Regulatory and Financial Consequences

According to estimates, the underestimation of PHEV emissions enabled several large carmaker companies to escape over €5bn in fines between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend approximately €500 extra per year in running costs than is assumed under lab conditions.

“The strong statements that automakers like to make about their plug-in hybrid vehicles are clearly far from the truth,” stated a automotive analyst. “Consumers are being duped into thinking that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are only slightly improved than regular gas and diesel cars in terms of fuel use, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been brought back into political discussions as automakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced intense pressure from the car industry and resistance from member states with large car industries.

Some senior politicians have proposed plug-in hybrids as a possible “compromise” option to include in the legislation.

One independent energy policy specialist, who was not involved with the study, 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 actual emissions.

“These findings show, without question, that the difference in official and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or conventional cars,” they said. “All regulatory changes concerning PHEVs should be made with extreme caution and considering that evidence.”