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Plug-in hybrid electric vehicles emit almost 5x greater global warming emissions than lab-reported figures show, as per a recent report.

Widening Gap Between Official and Real-World CO2 Output

Statistics reveals that PHEVs emit just 19% less CO₂ than conventional petrol and diesel vehicles, based on analysis conducted by a non-profit group. This contrasts sharply with laboratory tests, which assumed a 75% decrease in emissions.

Researchers examined information from in-vehicle energy use meters of eight hundred thousand cars sold in the EU between 2021 and 2023. The team discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported emissions are decreasing,” stated a senior analyst involved in the study. “That gap is growing and creates a significant issue. Consequently, PHEVs pollute almost as much as petrol cars.”

Key Reasons Driving the Discrepancy

Researchers linked the majority of the gap to overestimates of the “utility factor” – the ratio of kilometers travelled in battery mode compared to total mileage. They determined that just a quarter of travel was completed in electric mode, whereas official assumptions suggested over four-fifths.

Additionally, when running in electric mode, pollution levels were well above official estimates. This occurred because EV motors were insufficiently powerful sufficient to operate independently, leading to engines burning fossil fuels for nearly one-third of the distance covered in electric mode.

Policy and Financial Consequences

Based on calculations, the underestimation of PHEV CO2 output allowed four large automaker groups to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ targets.

Furthermore, drivers of PHEVs would pay about €500 more annually in operating costs than would be estimated under lab conditions.

“The strong claims that manufacturers often promote about their plug-in hybrid vehicles are clearly far from the truth,” commented a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of fuel use, CO₂ production, and running expenses.”

Political Debate and Industry Pressure

Hybrid vehicles have lately been drawn again into political discussions as carmakers have lobbied the EU to weaken CO₂ standards. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive industry and resistance from EU countries with large automotive manufacturing.

Several high-level officials have proposed plug-in hybrids as a possible “compromise” option to introduce in the legislation.

An external energy economics specialist, who was unaffiliated with the research, described the report a “highly valuable addition” after years in which segments of the automotive sector argued there was too little information to accurately assess actual emissions.

“The results show, without question, that the gap in lab and actual PHEV fuel consumption and CO₂ output is much, much greater than for petrol or conventional cars,” the expert said. “Any regulatory changes concerning PHEVs should be made with utmost caution and considering this evidence.”