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PHEVs release almost five times more global warming pollution than lab-reported data indicate, according to a recent report.

Widening Gap In Lab and Actual Emissions

Statistics shows that PHEVs release just one-fifth less CO₂ than traditional gas and diesel cars, according to analysis carried out by a advocacy group. That contrasts significantly with lab tests, which suggested a 75% reduction in emissions.

Researchers examined data from onboard fuel consumption meters of eight hundred thousand vehicles sold in the EU from 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than official figures, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official figures are falling,” said a lead analyst involved in the report. “That discrepancy is growing and creates a significant problem. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Reasons Driving the Discrepancy

Analysts attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric mode relative to overall mileage. The team determined that just 27% of driving was completed in EV mode, whereas official estimates assumed over four-fifths.

Additionally, when operating in EV mode, pollution levels were significantly higher than lab estimates. That occurred because EV motors were not strong enough to operate independently, leading to combustion motors using fossil fuels for almost one-third of the distance covered in electric mode.

Policy and Economic Consequences

Based on estimates, the underestimation of PHEV CO2 output enabled four large carmaker groups to avoid more than €5bn in penalties between 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 extra annually in running costs than would be estimated under laboratory tests.

“The bold statements that manufacturers like to make about their PHEV vehicles are clearly far from the truth,” commented a transport analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are helping the environment and cutting money. In reality, PHEVs are little improved than standard petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have lately been drawn back into political debates as automakers have pressed the European Union to relax CO₂ targets. A proposed ban on sales of new combustion engine cars in 2035 has faced heavy lobbying from the car industry and opposition from member states with significant automotive industries.

Some high-level politicians have proposed plug-in hybrids as a possible “flexibility” solution to introduce in the regulation.

One external energy economics expert, who was unaffiliated with the study, described the report a “very useful addition” after a long period in which parts of the automotive industry argued there was insufficient information to properly assess actual emissions.

“These findings show, without question, that the gap in official and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or diesel cars,” they said. “Any policy adjustments regarding PHEVs should be implemented with utmost caution and in the light of that evidence.”