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PHEVs emit nearly five times more global warming emissions than official figures show, as per a new report.

Growing Gap Between Lab and Real-World CO2 Output

Data reveals that PHEVs release just one-fifth lower CO₂ than traditional gas and diesel cars, based on analysis carried out by a non-profit group. That differs significantly with laboratory tests, which assumed a three-quarters decrease in emissions.

Researchers examined data from in-vehicle fuel consumption meters of 800,000 cars sold in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from 3.5 times in 2021.

“Actual emissions are rising, while official emissions are decreasing,” said a senior analyst participating in the study. “That gap is growing and poses a significant problem. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Driving the Emissions Gap

Analysts linked the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric power compared to overall distance. The team found that only 27% of driving was done in EV mode, whereas official assumptions assumed 84%.

Even, when operating in EV mode, pollution levels were well above lab projections. This happened because electric motors were not strong enough to operate independently, resulting to engines burning gasoline for almost a third of the travel completed in electric mode.

Regulatory and Economic Implications

According to calculations, the underestimation of PHEV CO2 output enabled four large carmaker companies to avoid over €5bn in penalties from 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ standards.

Additionally, owners of PHEVs would spend approximately €500 extra per year in running expenses than is estimated under lab conditions.

“The strong claims that manufacturers often promote about their PHEV vehicles are obviously way off the mark,” commented a transport analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Debate and Industry Pressure

Plug-in hybrid vehicles have recently been drawn back into political discussions as carmakers have pressed the European Union to weaken CO₂ standards. A proposed prohibition on new combustion engine vehicles in 2035 has faced intense pressure from the automotive industry and resistance from member states with large car manufacturing.

Some high-level politicians have suggested plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

One external energy economics expert, who was unaffiliated with the research, called the report a “very useful addition” after years in which segments of the automotive industry argued there was too little information to properly evaluate real-world emissions.

“The results show, without question, that the difference between official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or diesel vehicles,” the expert said. “All policy changes concerning PHEVs should be made with extreme caution and in the light of that data.”