Plug-in Hybrid electric Vehicles Emit Almost as Heavily as Gasoline Vehicles, Study Reveals

Plug-in hybrid electric vehicles release almost 5x more planet-heating pollution than lab-reported data indicate, according to a new report.

Growing Discrepancy In Lab and Real-World Emissions

Data shows that PHEVs emit just 19% lower CO₂ than traditional petrol and diesel cars, based on research conducted by a advocacy organization. That differs sharply with laboratory tests, which assumed a three-quarters reduction in pollution.

Researchers examined information from in-vehicle fuel consumption monitors of eight hundred thousand cars sold in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are falling,” stated a senior researcher involved in the study. “That gap is widening and creates a serious problem. As a result, PHEVs pollute almost as heavily as gasoline cars.”

Primary Factors Driving the Discrepancy

Analysts linked most of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in battery mode relative to overall mileage. The team determined that only 27% of travel was completed in EV mode, while lab assumptions assumed 84%.

Even, when running in electric mode, pollution amounts were well above official estimates. This occurred because electric motors were insufficiently powerful enough to function alone, resulting to engines burning gasoline for nearly one-third of the distance covered in EV mode.

Policy and Financial Consequences

According to calculations, the underestimation of PHEV CO2 output enabled several large automaker companies to escape over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would pay about €500 extra per year in running expenses than would be estimated under laboratory conditions.

“The bold claims that automakers often promote about their PHEV vehicles are clearly way off the truth,” stated a automotive analyst. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the planet and cutting money. Actually, PHEVs are little better than regular gas and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Policy Discussion and Industry Lobbying

Hybrid cars have recently been brought again into policy debates as carmakers have lobbied the EU to weaken CO₂ targets. A planned prohibition on new combustion engine cars in 2035 has faced heavy pressure from the car industry and opposition from EU countries with large automotive industries.

Some senior officials have proposed plug-in hybrids as a potential “compromise” option to introduce in the regulation.

One independent energy policy expert, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after a long period in which parts of the car industry claimed there was insufficient information to accurately assess real-world emissions.

“The results demonstrate, without question, that the gap between lab and real-world PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional vehicles,” the expert said. “All regulatory changes concerning PHEVs should be implemented with utmost caution and in the light of that evidence.”