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PHEVs release almost 5x more global warming emissions than official data indicate, according to a recent analysis.

Growing Gap In Lab and Actual CO2 Output

Data shows that PHEVs emit only 19% less CO₂ than conventional petrol and diesel vehicles, according to research carried out by a advocacy organization. This contrasts sharply with laboratory estimates, which suggested a three-quarters decrease in pollution.

Researchers studied data from onboard energy use monitors of 800,000 vehicles sold in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” said a lead researcher participating in the report. “This discrepancy is growing and poses a significant issue. Consequently, PHEVs pollute nearly as much as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers linked the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in electric power relative to overall distance. They found that only a quarter of travel was completed in EV mode, whereas official assumptions suggested 84%.

Additionally, when running in EV mode, emission amounts were well above lab projections. That occurred because electric motors were insufficiently powerful sufficient to operate independently, resulting to engines using fossil fuels for nearly a third of the distance covered in EV mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output allowed four major automaker groups to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would spend approximately €500 more per year in running expenses than is assumed under laboratory conditions.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are clearly far from the mark,” stated a transport expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Pressure

Hybrid cars have lately been brought again into political discussions as automakers have lobbied the European Union to weaken CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and resistance from member states with large automotive manufacturing.

Several senior officials have proposed plug-in hybrids as a possible “compromise” option to include in the legislation.

An independent energy economics expert, who was not involved with the study, called the report a “very useful addition” after a long period in which parts of the automotive industry claimed there was too little information to properly assess real-world CO2 output.

“The results show, without question, that the difference in official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or diesel vehicles,” the expert stated. “Any policy changes regarding PHEVs should be implemented with utmost care and considering that data.”