Plug-in Hybrid Vehicles Pollute Nearly as Much as Gasoline Cars, Study Reveals

Plug-in hybrid electric vehicles release almost 5x more global warming pollution than lab-reported figures indicate, according to a recent analysis.

Widening Gap In Official and Real-World CO2 Output

Data reveals that PHEVs release just one-fifth less CO₂ than traditional gas and diesel cars, according to analysis carried out by a non-profit organization. This differs sharply with laboratory estimates, which assumed a 75% reduction in pollution.

Analysts studied information from in-vehicle energy use monitors of 800,000 vehicles sold in the EU from 2021 and 2023. They found 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 lab-reported figures are decreasing,” said a lead researcher involved in the report. “This discrepancy is growing and creates a significant problem. Consequently, PHEVs emit almost as heavily as petrol vehicles.”

Key Factors Behind the Emissions Gap

Analysts attributed most of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers driven in battery mode relative to total mileage. They found that just 27% of driving was done in electric mode, whereas official assumptions suggested 84%.

Additionally, when operating in electric mode, emission amounts were significantly higher than lab estimates. This happened because electric motors were not strong enough to operate alone, leading to combustion motors burning fossil fuels for almost a third of the distance covered in electric mode.

Regulatory and Economic Consequences

According to estimates, the underestimation of PHEV emissions allowed four major automaker groups to escape over €5bn in fines between 2021 and 2023, by artificially simplifying compliance with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could pay about €500 extra per year in running costs than would be assumed under lab tests.

“The bold claims that automakers like to make about their PHEV vehicles are obviously way off the truth,” commented a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the planet and cutting costs. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Discussion and Industry Lobbying

Plug-in hybrid cars have recently been brought back into political debates as carmakers have pressed the European Union to weaken CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced intense lobbying from the automotive sector and resistance from EU countries with large automotive manufacturing.

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

An external energy policy expert, who was not involved with the study, described the report a “highly valuable contribution” after years in which segments of the car sector argued there was insufficient information to accurately evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ output is significantly larger than for petrol or diesel vehicles,” they stated. “Any regulatory adjustments regarding PHEVs should be made with utmost caution and considering that evidence.”