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PHEVs produce nearly 5x greater global warming emissions than lab-reported figures show, according to a recent analysis.

Growing Gap Between Official and Actual Emissions

Statistics shows that PHEVs release just 19% less CO₂ than traditional petrol and diesel cars, according to research carried out by a advocacy group. That differs sharply with lab estimates, which assumed a 75% reduction in emissions.

Analysts examined information from in-vehicle energy use monitors of 800,000 vehicles sold in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from 3.5 times in 2021.

“Real-world emissions are rising, while official emissions are falling,” stated a senior researcher involved in the study. “That gap is growing and creates a serious problem. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Primary Reasons Driving the Emissions Gap

Researchers linked most of the difference to overestimates of the “utility factor” – the percentage of kilometers travelled in electric power relative to overall distance. The team found that only 27% of driving was completed in EV mode, whereas lab estimates suggested 84%.

Additionally, when operating in EV mode, pollution amounts were significantly higher than lab estimates. This occurred because EV motors were insufficiently powerful enough to operate alone, leading to engines burning gasoline for nearly one-third of the travel covered in EV mode.

Policy and Economic Implications

Based on calculations, the lowballing of PHEV CO2 output allowed several large automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend about €500 more annually in running expenses than is assumed under lab conditions.

“The bold statements that automakers like to make about their plug-in hybrid cars are obviously far from the mark,” stated a automotive analyst. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the planet and saving money. In reality, PHEVs are little improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Political Debate and Automotive Lobbying

Hybrid cars have recently been drawn again into policy debates as automakers have pressed the European Union to weaken CO₂ standards. A proposed ban on new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and opposition from EU countries with significant car manufacturing.

Several high-level officials have proposed plug-in hybrids as a possible “flexibility” option to include in the legislation.

One external energy policy specialist, who was not involved with the study, called the report a “very useful contribution” after a long period in which segments of the car sector argued there was too little data to accurately evaluate actual emissions.

“The results show, beyond any doubt, that the difference between lab and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or diesel cars,” the expert said. “All regulatory adjustments regarding PHEVs should be made with utmost care and considering this data.”