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Plug-in hybrid cars emit almost 5x more planet-heating emissions than official data show, as per a new analysis.

Growing Discrepancy Between Lab and Real-World CO2 Output

Statistics reveals that PHEVs release just one-fifth less CO₂ than traditional gas and diesel vehicles, based on research conducted by a advocacy organization. This differs significantly with lab estimates, which assumed a 75% decrease in emissions.

Analysts examined information from in-vehicle energy use meters of 800,000 cars sold in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are falling,” said a senior researcher involved in the report. “This gap is growing and poses a serious issue. Consequently, PHEVs emit almost as much as petrol cars.”

Primary Reasons Behind the Discrepancy

Researchers linked the majority of the gap to overestimates of the “utility factor” – the percentage of miles driven in battery mode relative to overall mileage. They found that only a quarter of travel was done in electric mode, whereas lab assumptions assumed over four-fifths.

Even, when running in EV mode, emission levels were significantly higher than lab projections. This happened because electric motors were insufficiently powerful enough to function alone, resulting to engines burning fossil fuels for almost one-third of the travel completed in EV mode.

Regulatory and Financial Consequences

Based on estimates, the lowballing of PHEV emissions allowed four large automaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ targets.

Additionally, owners of PHEVs would pay approximately €500 more annually in running expenses than would be estimated under laboratory tests.

“The bold statements that automakers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a automotive analyst. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. In reality, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating expenses.”

Policy Discussion and Automotive Pressure

Hybrid vehicles have lately been brought again into policy debates as automakers have pressed the EU to relax CO₂ standards. A planned prohibition on new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and opposition from EU countries with significant car industries.

Several high-level politicians have suggested PHEVs as a potential “compromise” option to include in the regulation.

One external energy policy specialist, who was unaffiliated with the research, described the analysis a “highly valuable addition” after a long period in which segments of the car industry claimed there was insufficient information to accurately assess actual CO2 output.

“These findings show, beyond any doubt, that the gap in official and actual PHEV fuel consumption and CO₂ output is much, much larger than for petrol or conventional vehicles,” they stated. “Any policy adjustments regarding PHEVs should be implemented with utmost care and considering this data.”