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

Growing Discrepancy In Official and Real-World Emissions

Statistics reveals that PHEVs emit just 19% less CO₂ than conventional petrol and diesel cars, based on research conducted by a non-profit group. That contrasts sharply with lab tests, which suggested a three-quarters reduction in emissions.

Researchers examined information from in-vehicle fuel consumption meters of 800,000 vehicles sold in Europe between 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times higher than official figures, increased from 3.5 times in 2021.

“Actual emissions are rising, while lab-reported figures are decreasing,” said a senior researcher involved in the report. “That discrepancy is growing and poses a serious problem. Consequently, PHEVs pollute almost as heavily as gasoline vehicles.”

Primary Reasons Driving the Discrepancy

Analysts attributed the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles travelled in electric power relative to total mileage. The team found that just 27% of driving was done in EV mode, whereas official assumptions assumed 84%.

Additionally, when operating in EV mode, pollution amounts were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful sufficient to function alone, resulting to combustion motors using gasoline for nearly one-third of the distance completed in electric mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV emissions enabled several large carmaker companies to avoid over €5bn in penalties from 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ standards.

Additionally, owners of PHEVs could pay about €500 more per year in operating costs than is estimated under lab conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid cars are clearly far from the mark,” stated a transport analyst. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the planet and saving money. Actually, PHEVs are only slightly better than regular gas and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Political Debate and Automotive Pressure

Hybrid cars have recently been brought back into policy debates as carmakers have lobbied the European Union to weaken CO₂ targets. A planned prohibition on sales of new internal combustion cars in 2035 has faced heavy lobbying from the automotive sector and resistance from EU countries with large automotive manufacturing.

Some senior officials have proposed PHEVs as a potential “compromise” solution to introduce in the regulation.

An independent energy economics expert, who was unaffiliated with the study, described the analysis a “very useful addition” after a long period in which parts of the car industry argued there was too little information to properly assess real-world emissions.

“The results show, without question, that the difference between official and actual PHEV energy use and CO₂ output is significantly greater than for petrol or conventional cars,” they stated. “Any policy changes concerning PHEVs should be made with extreme caution and considering this evidence.”