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PHEVs produce almost 5x greater planet-heating pollution than lab-reported figures show, according to a recent report.

Widening Gap Between Official and Actual CO2 Output

Statistics shows that PHEVs release only one-fifth lower CO₂ than conventional petrol and diesel vehicles, based on analysis carried out by a non-profit organization. That contrasts significantly with laboratory estimates, which suggested a three-quarters reduction in pollution.

Researchers studied information from in-vehicle fuel consumption monitors of 800,000 vehicles sold in Europe between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are decreasing,” said a lead researcher involved in the report. “This discrepancy is widening and poses a significant problem. As a result, PHEVs emit almost as heavily as gasoline vehicles.”

Primary Reasons Behind the Emissions Gap

Researchers attributed the majority of the gap to inflated estimates of the “electric driving share” – the percentage of miles driven in battery mode relative to overall mileage. They determined that just 27% of driving was done in EV mode, whereas lab estimates suggested over four-fifths.

Additionally, when running in electric mode, pollution levels were well above lab projections. That happened because electric motors were not strong enough to operate alone, leading to engines using gasoline for nearly one-third of the travel covered in electric mode.

Regulatory and Financial Implications

According to calculations, the lowballing of PHEV emissions enabled several large automaker companies to avoid more than €5bn in penalties between 2021 and 2023, by falsely simplifying compliance with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 more annually in running expenses than would be assumed under lab tests.

“The bold statements that automakers like to make about their PHEV vehicles are obviously way off the truth,” commented a automotive analyst. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are little better than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Pressure

Hybrid cars have recently been drawn again into political discussions as automakers have lobbied the European Union to relax CO₂ targets. A proposed ban on new internal combustion cars in 2035 has faced intense lobbying from the car industry and opposition from EU countries with significant car industries.

Several high-level officials have proposed PHEVs as a potential “compromise” solution to introduce in the regulation.

One independent energy economics specialist, who was not involved with the research, described the report a “highly valuable contribution” after years in which segments of the car industry argued there was insufficient data to properly evaluate real-world emissions.

“The results demonstrate, without question, that the difference between lab and actual PHEV energy use and CO₂ emissions is much, much larger than for petrol or diesel vehicles,” the expert said. “All policy changes concerning PHEVs should be implemented with extreme care and considering that data.”