Plug-in Hybrid electric Vehicles Pollute Nearly as Heavily as Petrol Cars, Study Reveals

Plug-in hybrid electric vehicles release nearly 5x greater planet-heating emissions than lab-reported figures show, as per a new report.

Growing Discrepancy In Lab and Real-World CO2 Output

Data shows that PHEVs release just 19% less CO₂ than traditional gas and diesel cars, based on analysis conducted by a non-profit organization. That contrasts significantly with lab tests, which assumed a 75% decrease in pollution.

Researchers examined data from onboard fuel consumption monitors of eight hundred thousand vehicles registered in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater 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 senior researcher participating in the report. “This gap is widening and creates a serious problem. Consequently, PHEVs pollute nearly as heavily as gasoline cars.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the gap to overestimates of the “electric driving share” – the percentage of miles driven in electric mode compared to overall mileage. The team determined that only 27% of driving was done in electric mode, while lab assumptions assumed over four-fifths.

Even, when operating in EV mode, pollution amounts were significantly higher than official projections. This occurred because EV motors were insufficiently powerful enough to function independently, resulting to engines using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Economic Implications

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

Additionally, drivers of PHEVs could pay about €500 more per year in running costs than would be estimated under laboratory tests.

“The bold statements that manufacturers like to make about their PHEV vehicles are obviously far from the truth,” stated a automotive expert. “Consumers are being misled into believing that by buying a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly better than standard petrol and diesel vehicles in terms of energy use, CO₂ production, and operating costs.”

Political Debate and Automotive Pressure

Hybrid vehicles have recently been brought again into political debates as automakers have pressed the EU to weaken CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced intense pressure from the automotive industry and opposition from EU countries with large car manufacturing.

Some high-level politicians have proposed plug-in hybrids as a potential “flexibility” solution to introduce in the regulation.

An independent energy policy expert, who was unaffiliated with the research, described the analysis a “very useful addition” after a long period in which parts of the automotive sector argued there was too little information to properly assess real-world CO2 output.

“The results show, beyond any doubt, that the difference in lab and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional vehicles,” the expert stated. “Any policy changes regarding PHEVs should be implemented with extreme caution and considering that evidence.”