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Plug-in hybrid cars release nearly 5x more global warming pollution than official data show, as per a recent analysis.

Widening Gap In Official and Real-World Emissions

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than conventional petrol and diesel cars, based on research carried out by a non-profit group. That differs sharply with lab tests, which suggested a 75% decrease in emissions.

Analysts studied data from onboard energy use meters of eight hundred thousand cars sold in Europe from 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official figures are falling,” said a lead analyst participating in the study. “That discrepancy is widening and poses a significant problem. Consequently, PHEVs emit almost as heavily as gasoline cars.”

Key Factors Behind the Emissions Gap

Analysts linked most of the gap to overestimates of the “electric driving share” – the ratio of kilometers travelled in electric mode relative to total distance. The team determined that only a quarter of driving was done in electric mode, while lab estimates assumed 84%.

Even, when operating in EV mode, emission levels were well above lab estimates. That occurred because electric motors were insufficiently powerful sufficient to function alone, leading to combustion motors using fossil fuels for almost a third of the travel covered in EV mode.

Policy and Financial Implications

Based on calculations, the lowballing of PHEV emissions enabled several large automaker groups to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with European Union average fleet CO₂ targets.

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

“The strong claims that manufacturers often promote about their PHEV vehicles are clearly way off the truth,” stated a automotive expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting money. Actually, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy use, CO₂ emissions, and running costs.”

Policy Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought again into political debates as carmakers have lobbied the European Union to relax CO₂ targets. A planned ban on new internal combustion vehicles in 2035 has faced intense lobbying from the automotive industry and opposition from member states with significant automotive manufacturing.

Several high-level politicians have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

One external energy policy expert, who was unaffiliated with the research, described the report a “highly valuable addition” after a long period in which parts of the automotive sector claimed there was too little information to properly assess real-world emissions.

“These findings show, without question, that the gap between official and actual PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or diesel cars,” they stated. “Any policy adjustments concerning PHEVs should be made with utmost caution and in the light of that data.”