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Plug-in hybrid electric vehicles release nearly 5x greater global warming emissions than lab-reported figures show, as per a recent analysis.

Growing Gap Between Official and Actual Emissions

Data shows that PHEVs release just 19% less CO₂ than traditional gas and diesel cars, according to research carried out by a non-profit group. This contrasts significantly with laboratory estimates, which suggested a 75% reduction in emissions.

Analysts examined information from in-vehicle energy use meters of 800,000 vehicles sold in the EU from 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 lab-reported emissions are falling,” said a lead analyst participating in the report. “That gap is widening and poses a significant issue. Consequently, PHEVs pollute almost as much as petrol cars.”

Key Reasons Behind the Discrepancy

Researchers linked most of the gap to overestimates of the “utility factor” – the percentage of miles travelled in battery power relative to total mileage. They found that only 27% of driving was done in electric mode, whereas official assumptions assumed over four-fifths.

Even, when operating in EV mode, emission levels were significantly higher than official projections. This occurred because electric motors were not strong enough to operate alone, leading to combustion motors burning gasoline for almost one-third of the travel completed in electric mode.

Policy and Economic Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several major carmaker companies to avoid over €5bn in penalties between 2021 and 2023, by artificially easing adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 more annually in operating expenses than is assumed under lab tests.

“The bold statements that automakers like to make about their PHEV vehicles are obviously far from the truth,” commented a automotive expert. “Consumers are being misled into thinking that by buying a PHEV, they are helping the planet and cutting money. Actually, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of energy use, CO₂ production, and running costs.”

Policy Debate and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn back into policy discussions as carmakers have lobbied the European Union to relax CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy pressure from the car industry and opposition from EU countries with significant car industries.

Some high-level officials have proposed plug-in hybrids as a possible “flexibility” option to include in the legislation.

An external energy economics specialist, who was not involved with the research, called the analysis a “highly valuable addition” after a long period in which segments of the automotive industry argued there was too little information to accurately evaluate real-world emissions.

“These findings show, without question, that the gap in lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for gasoline or diesel vehicles,” the expert stated. “All policy changes regarding PHEVs should be implemented with utmost care and considering that data.”