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PHEVs release nearly 5x more planet-heating pollution than lab-reported figures indicate, according to a recent analysis.

Widening Discrepancy In Official and Actual CO2 Output

Data reveals that PHEVs release just 19% lower CO₂ than conventional petrol and diesel vehicles, according to research conducted by a non-profit organization. That differs significantly with laboratory estimates, which assumed a 75% decrease in pollution.

Analysts examined data from onboard fuel consumption meters of 800,000 cars registered in Europe between 2021 and 2023. They found that real-world CO₂ emissions from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Real-world emissions are rising, while official figures are decreasing,” stated a lead analyst participating in the study. “This discrepancy is widening and poses a serious problem. Consequently, PHEVs pollute almost as much as gasoline cars.”

Primary Factors Behind the Emissions Gap

Analysts attributed most of the difference to overestimates of the “utility factor” – the percentage of miles travelled in battery power relative to overall distance. The team determined that only 27% of driving was completed in EV mode, whereas lab estimates suggested over four-fifths.

Additionally, when operating in electric mode, pollution levels were well above lab estimates. That occurred because electric motors were insufficiently powerful enough to function independently, resulting to engines burning gasoline for almost a third of the distance covered in electric mode.

Policy and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output allowed several large automaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially simplifying compliance with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs would pay about €500 extra per year in running costs than is estimated under laboratory conditions.

“The bold statements that automakers like to make about their PHEV cars are obviously far from the truth,” stated a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the planet and saving costs. Actually, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel consumption, CO₂ emissions, and running expenses.”

Political Debate and Industry Pressure

Hybrid vehicles have lately been drawn again into policy discussions as carmakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on sales of new combustion engine cars in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with significant car industries.

Some high-level politicians have suggested PHEVs as a possible “compromise” solution to include in the regulation.

One independent energy economics expert, who was unaffiliated with the research, called the report a “highly valuable addition” after a long period in which parts of the car industry claimed there was insufficient information to properly assess real-world emissions.

“These findings show, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for petrol or diesel vehicles,” the expert said. “All policy changes regarding PHEVs should be implemented with utmost care and considering this data.”