Plug in Hybrid Vehicles Pollute Almost as Much as Petrol Vehicles, Study Finds

Plug-in hybrid electric vehicles emit nearly 5x more planet-heating pollution than lab-reported data indicate, as per a recent analysis.

Growing Discrepancy In Lab and Actual CO2 Output

Data reveals that PHEVs emit only 19% less CO₂ than conventional petrol and diesel cars, based on research carried out by a advocacy group. That differs significantly with lab estimates, which suggested a 75% reduction in pollution.

Analysts studied data from onboard energy use meters of 800,000 cars registered in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than official estimates, up from three and a half times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” said a senior researcher participating in the report. “This discrepancy is widening and poses a serious problem. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Key Reasons Behind the Discrepancy

Analysts attributed the majority of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in battery mode relative to total distance. They found that just a quarter of driving was done in electric mode, while official assumptions assumed over four-fifths.

Additionally, when running in electric mode, pollution amounts were well above official projections. This happened because EV motors were insufficiently powerful sufficient to function independently, leading to engines burning fossil fuels for almost a third of the distance completed in electric mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output allowed four major carmaker groups to avoid over €5bn in fines between 2021 and 2023, by artificially easing compliance with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend about €500 more annually in running costs than would be assumed under lab conditions.

“The strong claims that automakers like to make about their PHEV vehicles are clearly far from the truth,” commented a transport expert. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid cars have recently been brought back into policy debates as automakers have lobbied the European Union to weaken CO₂ standards. A proposed ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive sector and opposition from member states with significant car industries.

Several senior politicians have proposed PHEVs as a possible “compromise” solution to introduce in the regulation.

An external energy policy specialist, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which segments of the car sector argued there was too little data to properly evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference between lab and real-world PHEV fuel consumption and CO₂ output is much, much larger than for petrol or conventional cars,” the expert stated. “All regulatory changes regarding PHEVs should be implemented with utmost care and considering that data.”