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PHEVs release almost 5x greater global warming emissions than lab-reported figures show, as per a new report.

Widening Discrepancy Between Lab and Real-World CO2 Output

Data shows that PHEVs release only one-fifth less CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a non-profit organization. That contrasts significantly with laboratory estimates, which assumed a 75% reduction in pollution.

Researchers studied data from in-vehicle energy use meters of 800,000 vehicles sold in Europe from 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” said a senior analyst involved in the study. “That gap is widening and poses a significant issue. As a result, PHEVs emit nearly as much as petrol cars.”

Primary Factors Driving the Emissions Gap

Researchers attributed the majority of the difference to inflated estimates of the “electric driving share” – the ratio of miles driven in battery mode relative to total mileage. The team determined that just 27% of travel was completed in electric mode, whereas lab assumptions suggested over four-fifths.

Additionally, when operating in EV mode, emission amounts were well above official projections. That occurred because electric motors were insufficiently powerful enough to operate independently, resulting to engines burning fossil fuels for nearly a third of the distance completed in EV mode.

Regulatory and Financial Implications

According to estimates, the underestimation of PHEV emissions enabled four large carmaker companies to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with EU average fleet CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 more annually in running costs than would be assumed under laboratory conditions.

“The bold claims that manufacturers often promote about their plug-in hybrid cars are obviously far from the truth,” commented a automotive analyst. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the planet and cutting money. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy use, CO₂ production, and running expenses.”

Policy Discussion and Automotive Pressure

Hybrid cars have recently been brought again into political debates as automakers have pressed the EU to relax CO₂ standards. A planned ban on sales of new internal combustion vehicles in 2035 has faced intense pressure from the car industry and resistance from EU countries with large automotive manufacturing.

Some high-level officials have proposed PHEVs as a possible “compromise” option to include in the regulation.

An external energy policy specialist, who was not involved with the research, described the report a “very useful contribution” after years in which parts of the automotive sector argued there was too little information to accurately evaluate actual emissions.

“The results show, without question, that the difference between official and actual PHEV fuel consumption and CO₂ output is significantly greater than for gasoline or conventional cars,” the expert stated. “All policy adjustments regarding PHEVs should be made with utmost care and in the light of that evidence.”