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Plug-in hybrid electric vehicles emit almost five times greater global warming pollution than official data show, as per a recent analysis.

Widening Gap In Lab and Real-World Emissions

Data reveals that PHEVs release only 19% less CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy organization. This differs significantly with laboratory estimates, which suggested a 75% decrease in pollution.

Analysts studied data from in-vehicle energy use monitors of eight hundred thousand vehicles sold in the EU between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, increased from three and a half times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are decreasing,” said a senior researcher participating in the study. “That gap is widening and creates a significant issue. As a result, PHEVs pollute almost as heavily as gasoline vehicles.”

Key Factors Driving the Discrepancy

Analysts linked most of the gap to overestimates of the “electric driving share” – the ratio of miles driven in electric power relative to total mileage. The team determined that just 27% of travel was done in EV mode, whereas lab assumptions suggested 84%.

Additionally, when running in electric mode, pollution amounts were significantly higher than lab estimates. That occurred because EV motors were insufficiently powerful enough to function independently, leading to combustion motors using fossil fuels for almost a third of the travel covered in electric mode.

Policy and Economic Consequences

Based on estimates, the lowballing of PHEV emissions enabled four major automaker groups to escape more than €5bn in fines between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Additionally, drivers of PHEVs would spend about €500 more annually in running costs than is assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid cars are clearly far from 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. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of energy use, CO₂ production, and operating expenses.”

Policy Debate and Industry Pressure

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

Some high-level politicians have proposed PHEVs as a potential “flexibility” solution to introduce in the regulation.

One independent energy policy expert, who was not involved with the research, called the analysis a “very useful contribution” after years in which segments of the automotive sector claimed there was insufficient information to properly assess real-world emissions.

“These findings demonstrate, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert said. “All regulatory changes regarding PHEVs should be made with extreme caution and considering that evidence.”