🔗 Share this article

Plug-in hybrid electric vehicles emit almost five times more planet-heating pollution than official figures indicate, according to a recent report.

Widening Discrepancy Between Official and Actual Emissions

Data shows that PHEVs release only one-fifth less CO₂ than conventional petrol and diesel vehicles, according to research conducted by a advocacy organization. That differs sharply with lab tests, which assumed a 75% reduction in emissions.

Analysts studied data from in-vehicle fuel consumption monitors of 800,000 vehicles registered in the EU from 2021 and 2023. The team found that actual CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Real-world emissions are rising, while official figures are falling,” stated a senior researcher involved in the report. “That discrepancy is growing and poses a significant problem. Consequently, PHEVs pollute nearly as heavily as petrol vehicles.”

Key Factors Driving the Discrepancy

Researchers linked the majority of the difference to inflated estimates of the “utility factor” – the ratio of miles travelled in electric power compared to total mileage. The team determined that just 27% of travel was completed in EV mode, while lab estimates assumed over four-fifths.

Even, when running in EV mode, emission levels were significantly higher than lab projections. This occurred because EV motors were insufficiently powerful sufficient to function independently, resulting to combustion motors burning fossil fuels for nearly one-third of the travel completed in electric mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV CO2 output allowed four major automaker companies to escape over €5bn in penalties between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 extra annually in operating expenses than is assumed under laboratory tests.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are obviously way off the mark,” stated a automotive analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are only slightly improved than standard gas and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Political Debate and Automotive Lobbying

Plug-in hybrid vehicles have recently been brought back into policy debates as automakers have lobbied the EU to relax CO₂ standards. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the automotive sector and resistance from member states with significant automotive industries.

Some high-level politicians have suggested plug-in hybrids as a possible “flexibility” solution to introduce in the legislation.

One external energy policy expert, who was not involved with the research, described the analysis a “very useful addition” after years in which parts of the car sector argued there was too little data to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the gap in lab and real-world PHEV fuel consumption and CO₂ output is significantly larger than for gasoline or conventional cars,” they stated. “All policy changes concerning PHEVs should be made with utmost caution and considering this data.”