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Plug-in hybrid cars emit almost five times greater planet-heating emissions than official figures indicate, as per a recent analysis.

Growing Gap Between Lab and Real-World Emissions

Statistics reveals that PHEVs release just one-fifth less CO₂ than traditional petrol and diesel cars, according to research carried out by a non-profit group. That contrasts significantly with lab tests, which suggested a 75% reduction in pollution.

Researchers examined information from onboard fuel consumption meters of eight hundred thousand cars sold in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported emissions are falling,” said a lead analyst participating in the report. “That gap is widening and poses a significant problem. As a result, PHEVs emit nearly as heavily as petrol cars.”

Primary Reasons Behind the Emissions Gap

Researchers attributed most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric power relative to overall distance. They determined that just a quarter of driving was done in electric mode, whereas lab estimates suggested 84%.

Additionally, when operating in EV mode, emission levels were significantly higher than official projections. That happened because electric motors were insufficiently powerful enough to operate alone, leading to engines using gasoline for almost one-third of the travel covered in EV mode.

Policy and Economic Implications

Based on calculations, the lowballing of PHEV emissions allowed several large carmaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially simplifying compliance with EU average fleet CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 more per year in operating costs than is estimated under lab tests.

“The strong claims that manufacturers like to make about their PHEV cars are obviously way off the truth,” commented a transport analyst. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the environment and saving money. In reality, PHEVs are only slightly improved than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Policy Discussion and Industry Lobbying

Hybrid cars have recently been brought back into policy discussions as carmakers have lobbied the European Union to weaken CO₂ targets. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense lobbying from the car sector and opposition from EU countries with large car industries.

Several senior officials have proposed plug-in hybrids as a possible “compromise” solution to include in the regulation.

One external energy policy expert, who was not involved with the research, described the analysis a “highly valuable addition” after a long period in which segments of the automotive industry argued there was insufficient information to properly evaluate actual CO2 output.

“These findings show, without question, that the gap between lab and real-world PHEV energy use and CO₂ emissions is significantly larger than for petrol or conventional vehicles,” they stated. “Any policy adjustments concerning PHEVs should be implemented with utmost care and in the light of this data.”