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Plug-in hybrid electric vehicles release almost five times more global warming emissions than official figures show, as per a recent report.

Widening Gap Between Lab and Real-World CO2 Output

Statistics reveals that PHEVs emit only one-fifth less CO₂ than traditional petrol and diesel vehicles, according to research conducted by a advocacy organization. This contrasts sharply with lab tests, which suggested a three-quarters reduction in pollution.

Analysts studied information from in-vehicle energy use meters of 800,000 vehicles sold in Europe from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported emissions are decreasing,” said a lead researcher involved in the study. “That gap is widening and poses a serious problem. As a result, PHEVs pollute nearly as much as gasoline vehicles.”

Primary Factors Driving the Discrepancy

Analysts linked most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in battery power relative to total distance. They found that just a quarter of driving was done in EV mode, whereas lab assumptions suggested over four-fifths.

Additionally, when running in EV mode, emission amounts were significantly higher than official projections. This occurred because EV motors were not strong enough to function alone, leading to combustion motors using gasoline for nearly a third of the travel completed in EV mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV emissions allowed several major automaker groups to avoid over €5bn in penalties from 2021 and 2023, by falsely easing adherence with EU fleet-average CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 extra annually in running costs than would be assumed under lab conditions.

“The strong statements that manufacturers like to make about their plug-in hybrid cars are obviously way off the mark,” commented a transport analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Policy Debate and Automotive Pressure

Hybrid vehicles have recently been brought again into policy debates as automakers have lobbied the EU to relax CO₂ standards. A proposed prohibition on new internal combustion cars in 2035 has faced intense pressure from the automotive sector and resistance from member states with large car manufacturing.

Some senior politicians have suggested plug-in hybrids as a possible “compromise” option to introduce in the legislation.

One external energy policy expert, who was not involved with the study, described the report a “highly valuable contribution” after a long period in which parts of the automotive sector argued there was too little information to properly evaluate real-world CO2 output.

“These findings demonstrate, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for petrol or conventional cars,” the expert stated. “All policy adjustments regarding PHEVs should be implemented with utmost caution and in the light of this data.”