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PHEVs release nearly 5x greater planet-heating pollution than official data indicate, according to a new analysis.

Growing Gap In Lab and Actual CO2 Output

Statistics reveals that PHEVs emit just one-fifth lower CO₂ than traditional gas and diesel vehicles, based on research carried out by a advocacy group. This differs significantly with laboratory tests, which assumed a 75% decrease in pollution.

Analysts examined data from in-vehicle fuel consumption monitors of 800,000 vehicles registered in the EU between 2021 and 2023. The team found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab figures, increased from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” said a senior researcher involved in the report. “That gap is widening and creates a serious issue. Consequently, PHEVs pollute almost as heavily as petrol cars.”

Primary Reasons Driving the Emissions Gap

Researchers attributed the majority of the gap to overestimates of the “utility factor” – the percentage of miles driven in battery power relative to total mileage. They determined that only 27% of driving was done in EV mode, while lab estimates suggested 84%.

Even, when running in electric mode, pollution levels were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful enough to operate alone, resulting to engines burning gasoline for almost one-third of the travel completed in EV mode.

Regulatory and Economic Consequences

According to calculations, the underestimation of PHEV CO2 output enabled four large automaker companies to escape more than €5bn in penalties between 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ standards.

Furthermore, owners of PHEVs would pay approximately €500 extra per year in running expenses than is assumed under lab conditions.

“The strong statements that automakers like to make about their PHEV cars are clearly way off the mark,” commented a automotive analyst. “Buyers are being misled into believing that by buying a PHEV, they are benefiting the environment and cutting costs. In reality, PHEVs are little improved than regular gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Lobbying

Hybrid cars have lately been drawn back into policy discussions as automakers have pressed the European Union to relax CO₂ standards. A proposed ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the car industry and resistance from EU countries with significant car industries.

Some senior officials have suggested PHEVs as a possible “flexibility” option to include in the regulation.

An external energy economics expert, who was unaffiliated with the research, described the analysis a “highly valuable contribution” after years in which parts of the automotive industry claimed there was too little data to accurately evaluate actual CO2 output.

“These findings demonstrate, beyond any doubt, that the difference between official and actual PHEV energy use and CO₂ emissions is significantly larger than for gasoline or conventional vehicles,” the expert said. “All regulatory adjustments regarding PHEVs should be implemented with utmost care and considering that evidence.”