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PHEVs release almost five times greater global warming pollution than official figures show, as per a new analysis.

Growing Gap Between Lab and Real-World Emissions

Data shows that PHEVs emit just 19% less CO₂ than conventional gas and diesel cars, according to analysis carried out by a advocacy organization. This contrasts sharply with lab estimates, which suggested a 75% decrease in emissions.

Analysts examined information from in-vehicle energy use monitors of 800,000 vehicles sold in the EU from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are falling,” stated a senior researcher involved in the study. “That discrepancy is growing and creates a serious issue. As a result, PHEVs pollute almost as heavily as petrol cars.”

Key Factors Driving the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in battery power relative to total distance. They found that only 27% of driving was completed in electric mode, while official estimates suggested 84%.

Additionally, when operating in electric mode, emission levels were significantly higher than lab projections. That occurred because electric motors were not strong enough to function independently, resulting to combustion motors using gasoline for almost one-third of the travel covered in EV mode.

Regulatory and Economic Implications

According to estimates, the lowballing of PHEV CO2 output enabled four major automaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ targets.

Additionally, owners of PHEVs would pay approximately €500 more per year in running costs than would be assumed under laboratory conditions.

“The strong claims that automakers like to make about their PHEV cars are clearly way off the truth,” stated a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are helping the planet and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Debate and Automotive Pressure

Plug-in hybrid vehicles have lately been drawn back into political discussions as carmakers have lobbied the EU to relax CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with large car manufacturing.

Some high-level politicians have suggested PHEVs as a potential “compromise” solution to introduce in the legislation.

One independent energy economics expert, who was not involved with the research, described the report a “highly valuable contribution” after years in which parts of the automotive sector argued there was insufficient information to accurately assess real-world emissions.

“These findings show, beyond any doubt, that the difference in official and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or conventional cars,” they stated. “All policy changes concerning PHEVs should be implemented with extreme caution and considering that data.”