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Plug-in hybrid cars emit almost five times greater planet-heating pollution than official figures show, as per a recent report.

Widening Gap Between Official and Actual CO2 Output

Data shows that PHEVs release just one-fifth less CO₂ than traditional gas and diesel cars, based on research carried out by a advocacy organization. This contrasts significantly with laboratory tests, which assumed a three-quarters decrease in pollution.

Researchers examined information from in-vehicle energy use monitors of 800,000 vehicles sold in Europe from 2021 and 2023. They discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than official figures, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a lead researcher involved in the report. “This gap is widening and poses a serious problem. Consequently, PHEVs emit almost as much as petrol cars.”

Key Factors Behind the Discrepancy

Analysts attributed most of the gap to overestimates of the “utility factor” – the ratio of miles driven in battery power compared to overall mileage. The team determined that just a quarter of driving was done in electric mode, whereas official assumptions suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were significantly higher than official estimates. That happened because electric motors were not strong enough to function independently, resulting to combustion motors burning fossil fuels for almost one-third of the travel completed in EV mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output enabled four large carmaker groups to escape over €5bn in penalties from 2021 and 2023, by artificially simplifying adherence with European Union fleet-average CO₂ targets.

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

“The bold claims that manufacturers like to make about their PHEV vehicles are clearly far from the mark,” commented a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have lately been brought back into political discussions as automakers have lobbied the EU to weaken CO₂ targets. A planned ban on new internal combustion cars in 2035 has faced heavy pressure from the car industry and opposition from EU countries with large automotive manufacturing.

Some high-level officials have proposed PHEVs as a possible “flexibility” option to include in the regulation.

One independent energy economics specialist, who was unaffiliated with the research, called the report a “very useful addition” after years in which parts of the automotive sector argued there was too little information to properly assess real-world CO2 output.

“The results show, without question, that the gap in official and real-world PHEV energy use and CO₂ emissions is much, much greater than for gasoline or conventional cars,” they stated. “All policy changes concerning PHEVs should be implemented with extreme care and in the light of that data.”