🔗 Share this article

Plug-in hybrid electric vehicles produce almost 5x greater global warming pollution than lab-reported data show, according to a new analysis.

Widening Gap Between Official and Real-World Emissions

Statistics reveals that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel vehicles, according to analysis conducted by a non-profit organization. That differs sharply with laboratory estimates, which suggested a three-quarters decrease in pollution.

Analysts examined data from onboard fuel consumption meters of eight hundred thousand cars sold in Europe from 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” said a lead analyst involved in the study. “This discrepancy is widening and creates a significant issue. Consequently, PHEVs pollute almost as heavily as petrol vehicles.”

Key Factors Behind the Emissions Gap

Analysts attributed most of the difference to overestimates of the “utility factor” – the ratio of miles driven in battery power relative to total mileage. They found that just 27% of driving was done in EV mode, while official estimates suggested over four-fifths.

Additionally, when running in EV mode, emission amounts were well above lab estimates. This happened because EV motors were not strong enough to function alone, resulting to engines using gasoline for nearly one-third of the travel completed in EV mode.

Policy and Financial Implications

According to estimates, the lowballing of PHEV emissions enabled four large carmaker groups to avoid more than €5bn in fines from 2021 and 2023, by artificially easing compliance with European Union average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend approximately €500 extra per year in running costs than is estimated under laboratory conditions.

“The bold statements that manufacturers often promote about their PHEV vehicles are clearly far from the truth,” commented a automotive analyst. “Consumers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ production, and running costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn again into policy debates as carmakers have lobbied the European Union to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive industry and opposition from member states with large car industries.

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

An independent energy policy expert, who was not involved with the research, described the report a “very useful contribution” after a long period in which segments of the car sector argued there was too little information to properly evaluate real-world CO2 output.

“These findings show, beyond any doubt, that the gap in lab and actual PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel cars,” the expert said. “All policy changes regarding PHEVs should be implemented with utmost caution and in the light of that data.”