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PHEVs produce almost 5x greater planet-heating emissions than lab-reported data show, according to a recent analysis.

Widening Gap In Lab and Real-World CO2 Output

Statistics reveals that PHEVs release only one-fifth less CO₂ than conventional gas and diesel vehicles, according to analysis conducted by a advocacy organization. This contrasts sharply with lab estimates, which suggested a 75% decrease in pollution.

Researchers examined data from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, up from three and a half times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” said a lead analyst involved in the report. “This discrepancy is growing and creates a significant problem. As a result, PHEVs pollute almost as heavily as petrol cars.”

Primary Factors Behind the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “electric driving share” – the percentage of kilometers driven in battery power compared to total distance. The team found that only a quarter of driving was completed in electric mode, whereas official assumptions assumed 84%.

Even, when operating in electric mode, pollution levels were well above lab estimates. That happened because EV motors were not strong enough to function alone, leading to engines using gasoline for nearly a third of the travel covered in electric mode.

Regulatory and Financial Consequences

According to estimates, the lowballing of PHEV emissions enabled four major carmaker groups to escape more than €5bn in fines between 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs would pay about €500 extra per year in running costs than is assumed under laboratory tests.

“The strong statements that automakers like to make about their PHEV vehicles are obviously far from the mark,” commented a transport analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are only slightly improved than standard petrol and diesel cars in terms of fuel use, CO₂ production, and running costs.”

Political Debate and Industry Pressure

Hybrid vehicles have recently been brought back into political debates as carmakers have lobbied the European Union to relax CO₂ standards. A planned ban on new combustion engine cars in 2035 has faced intense pressure from the automotive sector and resistance from member states with large automotive manufacturing.

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

An external energy economics expert, who was unaffiliated with the research, called the analysis a “highly valuable contribution” after years in which parts of the automotive industry claimed there was too little information to properly evaluate actual CO2 output.

“These findings demonstrate, without question, that the difference in official and real-world PHEV energy use and CO₂ output is significantly larger than for gasoline or diesel vehicles,” they stated. “Any policy changes concerning PHEVs should be made with utmost caution and in the light of that data.”