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Plug-in hybrid electric vehicles produce almost five times more planet-heating emissions than lab-reported figures indicate, according to a recent analysis.

Growing Discrepancy Between Lab and Real-World CO2 Output

Statistics reveals that PHEVs emit only 19% lower CO₂ than conventional gas and diesel cars, according to research conducted by a advocacy organization. That differs sharply with laboratory estimates, which assumed a 75% reduction in emissions.

Researchers examined information from onboard fuel consumption monitors of 800,000 cars sold in Europe between 2021 and 2023. They found that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than lab figures, increased from 3.5 times in 2021.

“Actual CO2 output are increasing, while official emissions are decreasing,” stated a lead analyst participating in the study. “This gap is widening and poses a serious problem. Consequently, PHEVs pollute almost as heavily as petrol cars.”

Primary Reasons Behind the Discrepancy

Analysts linked the majority of the gap to overestimates of the “electric driving share” – the percentage of kilometers driven in battery mode relative to overall distance. They determined that only 27% of driving was done in electric mode, whereas lab estimates suggested 84%.

Even, when operating in EV mode, pollution amounts were well above lab projections. That occurred because electric motors were insufficiently powerful enough to function alone, leading to engines using gasoline for almost one-third of the travel covered in electric mode.

Policy and Economic Implications

Based on calculations, the lowballing of PHEV CO2 output enabled several large automaker groups to escape over €5bn in fines from 2021 and 2023, by artificially easing adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs could spend approximately €500 more per year in running costs than would be assumed under laboratory conditions.

“The bold statements that automakers like to make about their PHEV vehicles are clearly way off the truth,” stated a automotive expert. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the planet and saving money. In reality, PHEVs are only slightly improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ production, and operating expenses.”

Policy Discussion and Industry Lobbying

Plug-in hybrid cars have recently been drawn back into policy debates as automakers have pressed the EU to weaken CO₂ targets. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense pressure from the automotive sector and resistance from member states with significant automotive industries.

Some high-level politicians have suggested PHEVs as a potential “compromise” option to include in the legislation.

One external energy economics expert, who was unaffiliated with the research, called the report a “highly valuable addition” after years in which parts of the automotive sector argued there was too little data to properly evaluate actual emissions.

“The results demonstrate, beyond any doubt, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or diesel cars,” they stated. “Any regulatory changes concerning PHEVs should be made with utmost care and considering this data.”