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PHEVs produce almost 5x greater planet-heating emissions than official figures indicate, as per a new report.

Widening Gap In Lab and Actual Emissions

Data shows that PHEVs release just 19% less CO₂ than traditional gas and diesel cars, based on research carried out by a advocacy organization. This differs sharply with laboratory tests, which suggested a 75% decrease in emissions.

Analysts studied data from in-vehicle fuel consumption meters of eight hundred thousand cars sold in Europe between 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times higher than lab estimates, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while official emissions are decreasing,” said a senior researcher participating in the report. “That discrepancy is growing and poses a significant issue. As a result, PHEVs emit nearly as heavily as gasoline vehicles.”

Primary Factors Behind the Discrepancy

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the ratio of miles driven in battery mode compared to overall mileage. They determined that just a quarter of driving was completed in electric mode, while official assumptions suggested over four-fifths.

Additionally, when running in EV mode, pollution amounts were well above official estimates. That occurred because electric motors were insufficiently powerful enough to function independently, leading to engines burning fossil fuels for almost one-third of the distance covered in EV mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV CO2 output allowed four large carmaker groups to avoid over €5bn in penalties from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

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

“The bold statements that automakers often promote about their plug-in hybrid cars are obviously way off the truth,” commented a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of energy consumption, CO₂ emissions, and running expenses.”

Policy Debate and Automotive Lobbying

Plug-in hybrid cars have recently been drawn again into political debates as automakers have lobbied the EU to weaken CO₂ standards. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy pressure from the automotive sector and opposition from EU countries with significant automotive manufacturing.

Several senior politicians have suggested plug-in hybrids as a possible “flexibility” solution to include in the regulation.

An independent 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 industry claimed there was insufficient information to properly evaluate actual emissions.

“These findings demonstrate, without question, that the gap between lab and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel cars,” they stated. “Any regulatory changes regarding PHEVs should be implemented with utmost caution and considering that evidence.”