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Plug-in hybrid electric vehicles produce almost five times more global warming pollution than official figures show, according to a recent report.

Growing Gap Between Lab and Actual CO2 Output

Data shows that PHEVs release just one-fifth less CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit group. That contrasts significantly with laboratory estimates, which suggested a 75% decrease in emissions.

Analysts examined data from in-vehicle fuel consumption monitors of 800,000 cars sold in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while lab-reported figures are falling,” stated a lead analyst participating in the report. “This gap is growing and creates a significant issue. As a result, PHEVs pollute almost as heavily as petrol vehicles.”

Primary Factors Behind the Emissions Gap

Researchers linked the majority of the difference to overestimates of the “electric driving share” – the percentage of kilometers travelled in battery power compared to total distance. The team determined that just a quarter of travel was completed in EV mode, whereas official assumptions assumed 84%.

Additionally, when running in electric mode, pollution levels were significantly higher than lab estimates. This occurred because electric motors were insufficiently powerful sufficient to operate alone, leading to engines burning fossil fuels for almost a third of the distance completed in electric mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV emissions enabled four major automaker companies to escape over €5bn in penalties between 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay about €500 more annually in operating expenses than is estimated under lab conditions.

“The bold statements that manufacturers like to make about their PHEV cars are obviously far from the truth,” commented a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and saving money. In reality, PHEVs are little better than regular petrol and diesel cars in terms of energy use, CO₂ emissions, and operating costs.”

Political Debate and Industry Lobbying

Hybrid cars have recently been brought back into political debates as carmakers have pressed the European Union to weaken CO₂ standards. A proposed ban on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and resistance from member states with significant automotive industries.

Several senior officials have proposed PHEVs as a possible “flexibility” option to include in the regulation.

An independent energy policy specialist, who was not involved with the research, called the analysis a “very useful contribution” after a long period in which segments of the car industry argued there was too little information to accurately assess actual CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ output is much, much larger than for petrol or diesel cars,” they said. “Any policy changes concerning PHEVs should be made with extreme care and in the light of that data.”