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Plug-in hybrid electric vehicles release almost five times more planet-heating emissions than official data indicate, as per a recent analysis.

Growing Gap In Lab and Real-World Emissions

Data shows that PHEVs release just 19% less CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a advocacy organization. That differs significantly with laboratory tests, which assumed a 75% reduction in pollution.

Analysts examined information from onboard energy use meters of eight hundred thousand cars sold in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” stated a lead analyst participating in the report. “This gap is widening and creates a significant issue. Consequently, PHEVs pollute almost as heavily as petrol cars.”

Key Reasons Driving the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers driven in battery power relative to overall distance. The team found that just a quarter of travel was completed in electric mode, while official assumptions suggested over four-fifths.

Additionally, when running in electric mode, emission amounts were well above lab estimates. This happened because electric motors were not strong enough to function alone, resulting to combustion motors using fossil fuels for nearly one-third of the travel covered in electric mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV emissions allowed four major carmaker groups to escape over €5bn in fines from 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 more per year in running expenses than would be assumed under lab tests.

“The bold statements that manufacturers often promote about their PHEV cars are obviously way off the truth,” stated a automotive expert. “Buyers are being misled into believing that by buying a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly better than regular gas and diesel vehicles in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have recently been brought back into policy discussions as automakers have pressed the EU to weaken CO₂ targets. A planned prohibition on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the car industry and resistance from EU countries with large car manufacturing.

Several senior officials have proposed PHEVs as a potential “compromise” option to introduce in the regulation.

One external energy economics specialist, who was not involved with the research, described the analysis a “highly valuable contribution” after years in which segments of the automotive sector argued there was too little data to properly assess actual CO2 output.

“The results show, without question, that the gap in official and actual PHEV energy use and CO₂ emissions is significantly greater than for gasoline or diesel vehicles,” they said. “Any regulatory adjustments regarding PHEVs should be made with extreme care and considering that evidence.”