🔗 Share this article

PHEVs produce nearly five times more planet-heating emissions than lab-reported figures indicate, according to a new report.

Growing Discrepancy Between Lab and Real-World CO2 Output

Data shows that PHEVs release just 19% less CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a non-profit group. That contrasts sharply with laboratory estimates, which assumed a 75% reduction in emissions.

Analysts studied information from in-vehicle fuel consumption meters of eight hundred thousand vehicles sold in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, up from 3.5 times in 2021.

“Real-world CO2 output are increasing, while official emissions are decreasing,” said a lead researcher participating in the study. “This discrepancy is widening and creates a significant issue. As a result, PHEVs pollute nearly as much as gasoline vehicles.”

Primary Reasons Behind the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric power relative to overall distance. They found that just 27% of travel was done in EV mode, whereas lab assumptions assumed 84%.

Even, when running in EV mode, pollution amounts were well above lab estimates. This happened because electric motors were not strong sufficient to operate alone, resulting to engines using gasoline for almost one-third of the travel completed in EV mode.

Regulatory and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output allowed four major automaker groups to avoid over €5bn in penalties between 2021 and 2023, by falsely easing compliance with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs would spend about €500 more annually in running expenses than is assumed under laboratory conditions.

“The strong statements that automakers often promote about their plug-in hybrid cars are obviously way off the truth,” stated a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and saving money. Actually, PHEVs are only slightly better than regular petrol and diesel cars in terms of energy use, CO₂ production, and operating expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have lately been drawn back into political discussions as carmakers have lobbied the European Union to relax CO₂ targets. A planned ban on new combustion engine cars in 2035 has faced intense lobbying from the car industry and opposition from member states with significant automotive manufacturing.

Several high-level politicians have suggested PHEVs as a potential “compromise” solution to include in the regulation.

An independent energy economics specialist, who was not involved with the study, called the analysis a “highly valuable contribution” after a long period in which parts of the car industry claimed there was insufficient information to properly evaluate actual emissions.

“The results show, without question, that the difference between lab and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel cars,” they stated. “Any policy changes concerning PHEVs should be made with utmost caution and considering this evidence.”