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PHEVs release nearly five times more global warming pollution than lab-reported figures show, as per a new report.

Widening Discrepancy Between Official and Actual Emissions

Data shows that PHEVs emit only one-fifth lower CO₂ than traditional gas and diesel vehicles, according to research conducted by a advocacy organization. That differs significantly with laboratory estimates, which assumed a 75% decrease in pollution.

Researchers examined information from onboard energy use monitors of eight hundred thousand cars registered in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while official figures are decreasing,” stated a lead researcher participating in the report. “That discrepancy is widening and poses a significant problem. Consequently, PHEVs emit nearly as much as petrol vehicles.”

Primary Factors Driving the Emissions Gap

Researchers attributed most of the gap to overestimates of the “utility factor” – the ratio of miles driven in electric mode compared to total distance. They determined that just 27% of travel was done in electric mode, while official estimates suggested over four-fifths.

Additionally, when operating in electric mode, emission amounts were significantly higher than official estimates. This happened because EV motors were insufficiently powerful sufficient to operate independently, resulting to combustion motors burning fossil fuels for nearly one-third of the travel completed in EV mode.

Regulatory and Financial Implications

Based on calculations, the lowballing of PHEV CO2 output enabled four large carmaker companies to escape more than €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs could spend approximately €500 extra annually in running costs than would be assumed under laboratory conditions.

“The strong claims that automakers like to make about their plug-in hybrid cars are obviously way off the truth,” commented a transport expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly better than regular gas and diesel cars in terms of fuel consumption, CO₂ emissions, and running costs.”

Policy Discussion and Industry Pressure

Plug-in hybrid cars have lately been brought back into policy debates as carmakers have pressed the EU to weaken CO₂ standards. A proposed ban on sales of new combustion engine vehicles in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with large car manufacturing.

Some high-level politicians have proposed plug-in hybrids as a potential “compromise” option to introduce in the legislation.

One external energy economics expert, who was not involved with the study, called the report a “very useful contribution” after years in which segments of the automotive sector argued there was too little data to accurately evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ output is much, much larger than for petrol or diesel vehicles,” the expert said. “All regulatory adjustments concerning PHEVs should be made with extreme caution and in the light of that evidence.”