Plug in Hybrid Vehicles Pollute Nearly as Heavily as Petrol Vehicles, Report Finds

Plug-in hybrid electric vehicles emit almost five times greater global warming emissions than lab-reported data show, as per a new report.

Growing Discrepancy In Lab and Real-World Emissions

Statistics shows that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel cars, based on research carried out by a non-profit organization. That differs significantly with laboratory tests, which suggested a three-quarters decrease in pollution.

Researchers studied data from in-vehicle energy use meters of 800,000 vehicles registered in Europe from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while lab-reported emissions are decreasing,” said a senior researcher involved in the report. “This gap is growing and poses a significant problem. As a result, PHEVs pollute nearly as much as petrol vehicles.”

Primary Reasons Driving the Discrepancy

Researchers linked most of the gap to overestimates of the “utility factor” – the percentage of kilometers driven in electric mode relative to total distance. They determined that just 27% of driving was completed in EV mode, while lab estimates suggested over four-fifths.

Additionally, when operating in EV mode, emission amounts were well above official projections. This occurred because EV motors were not strong enough to operate alone, resulting to combustion motors burning fossil fuels for nearly a third of the travel completed in EV mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV CO2 output enabled four major carmaker companies to avoid over €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Furthermore, owners of PHEVs would spend about €500 more annually in operating expenses than would be assumed under lab conditions.

“The strong statements that manufacturers often promote about their PHEV vehicles are obviously way off the mark,” stated a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and cutting money. In reality, PHEVs are little improved than standard petrol and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Policy Discussion and Industry Pressure

Hybrid vehicles have recently been brought again into policy discussions as carmakers have lobbied the EU to weaken CO₂ targets. A planned ban on sales of new combustion engine cars in 2035 has faced heavy pressure from the automotive sector and resistance from member states with large car industries.

Some high-level officials have suggested plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

One external energy policy expert, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after years in which segments of the car sector claimed there was too little data to properly assess actual emissions.

“The results demonstrate, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or conventional vehicles,” they said. “Any regulatory changes concerning PHEVs should be implemented with extreme caution and in the light of that data.”