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PHEVs release nearly five times greater global warming pollution than official figures indicate, according to a recent analysis.

Widening Discrepancy In Official and Actual CO2 Output

Statistics reveals that PHEVs emit just one-fifth less CO₂ than conventional gas and diesel vehicles, according to research carried out by a advocacy group. This differs sharply with lab estimates, which suggested a three-quarters reduction in emissions.

Analysts studied data from in-vehicle energy use meters of 800,000 vehicles sold in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Real-world emissions are rising, while lab-reported figures are decreasing,” stated a senior researcher involved in the report. “That gap is growing and poses a significant problem. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Reasons Behind the Emissions Gap

Researchers linked most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in battery power compared to total mileage. They determined that only a quarter of travel was completed in electric mode, while official assumptions assumed 84%.

Additionally, when running in electric mode, pollution amounts were significantly higher than lab projections. This happened because electric motors were not strong sufficient to operate alone, leading to engines burning fossil fuels for nearly one-third of the travel covered in EV mode.

Regulatory and Economic Consequences

According to estimates, the lowballing of PHEV CO2 output allowed several large automaker groups to avoid more than €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay about €500 more per year in operating expenses than is estimated under laboratory tests.

“The bold statements that manufacturers often promote about their plug-in hybrid cars are obviously far from the mark,” stated a transport expert. “Buyers are being duped into thinking that by buying a PHEV, they are helping the planet and saving costs. In reality, PHEVs are little better than regular gas and diesel cars in terms of fuel use, CO₂ production, and operating expenses.”

Political Debate and Industry Pressure

Plug-in hybrid cars have lately been drawn back into policy discussions as carmakers have pressed the EU to relax CO₂ standards. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car industry and opposition from member states with large automotive industries.

Several high-level politicians have suggested plug-in hybrids as a potential “flexibility” solution to include in the legislation.

An independent energy economics expert, who was not involved with the research, described the report a “very useful contribution” after years in which parts of the automotive sector argued there was too little information to properly assess actual emissions.

“The results demonstrate, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel vehicles,” the expert said. “All policy adjustments concerning PHEVs should be implemented with utmost care and in the light of this data.”