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PHEVs emit almost five times greater planet-heating emissions than lab-reported data show, as per a new analysis.

Widening Discrepancy Between Lab and Actual Emissions

Statistics reveals that PHEVs release just 19% lower CO₂ than traditional gas and diesel vehicles, according to research carried out by a advocacy group. This differs significantly with laboratory estimates, which suggested a 75% reduction in pollution.

Analysts examined information from in-vehicle energy use monitors of 800,000 vehicles sold in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are increasing, while official figures are decreasing,” said a senior researcher participating in the study. “This discrepancy is widening and poses a serious issue. Consequently, PHEVs emit nearly as heavily as gasoline cars.”

Key Reasons Driving the Discrepancy

Analysts linked the majority of the difference to inflated estimates of the “utility factor” – the percentage of kilometers travelled in electric mode relative to overall mileage. The team determined that just 27% of driving was done in EV mode, whereas lab estimates assumed 84%.

Additionally, when operating in EV mode, emission levels were well above lab projections. That happened because electric motors were not strong sufficient to operate alone, resulting to engines burning gasoline for almost a third of the distance completed in electric mode.

Regulatory and Economic Implications

Based on estimates, the lowballing of PHEV emissions enabled four major carmaker groups to escape over €5bn in fines from 2021 and 2023, by falsely easing compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs would spend approximately €500 more per year in operating costs than would be estimated under lab conditions.

“The bold statements that manufacturers like to make about their plug-in hybrid vehicles are clearly way off the truth,” commented a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of fuel consumption, CO₂ production, and running costs.”

Political Debate and Automotive Pressure

Plug-in hybrid vehicles have recently been brought back into policy discussions as carmakers have lobbied the European Union to weaken CO₂ standards. A planned prohibition on sales of new combustion engine vehicles in 2035 has faced heavy lobbying from the car industry and resistance from EU countries with significant car industries.

Several senior politicians have suggested PHEVs as a potential “compromise” option to introduce in the legislation.

An independent energy economics specialist, who was not involved with the research, called the analysis a “very useful contribution” after a long period in which segments of the car sector argued there was too little data to accurately assess real-world emissions.

“These findings show, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or diesel vehicles,” they stated. “Any regulatory changes concerning PHEVs should be made with extreme care and in the light of that data.”