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Plug-in hybrid cars emit almost 5x more planet-heating emissions than lab-reported data show, as per a new report.

Growing Gap In Lab and Actual Emissions

Statistics reveals that PHEVs release only one-fifth lower CO₂ than traditional petrol and diesel vehicles, according to analysis carried out by a advocacy group. That differs sharply with lab tests, which suggested a 75% decrease in pollution.

Analysts studied data from in-vehicle energy use monitors of 800,000 cars sold in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, up from three and a half times in 2021.

“Real-world emissions are increasing, while lab-reported emissions are falling,” said a senior researcher involved in the study. “This gap is widening and poses a significant issue. As a result, PHEVs pollute almost as much as petrol cars.”

Key Factors Behind the Emissions Gap

Researchers attributed most of the difference to overestimates of the “utility factor” – the ratio of miles travelled in electric mode compared to overall mileage. They found that just a quarter of travel was completed in EV mode, whereas official estimates assumed over four-fifths.

Additionally, when operating in electric mode, pollution amounts were well above official estimates. That occurred because EV motors were not strong enough to operate independently, leading to engines burning gasoline for almost a third of the travel completed in EV mode.

Policy and Financial Implications

According to estimates, the lowballing of PHEV CO2 output enabled four large automaker groups to escape more than €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would spend approximately €500 extra per year in running expenses than would be assumed under lab conditions.

“The strong statements that manufacturers like to make about their PHEV cars are obviously way off the mark,” commented a automotive expert. “Consumers are being duped into thinking that by purchasing a PHEV, they are helping the environment and cutting costs. Actually, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy use, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid vehicles have lately been drawn back into policy discussions as carmakers have pressed the European Union to weaken CO₂ targets. A proposed prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car sector and opposition from EU countries with significant automotive industries.

Several senior officials have proposed plug-in hybrids as a possible “compromise” solution to introduce in the legislation.

An independent energy economics expert, who was unaffiliated with the study, called the analysis a “highly valuable addition” after a long period in which segments of the car industry argued there was too little information to accurately assess actual CO2 output.

“The results demonstrate, without question, that the difference between lab and real-world PHEV energy use and CO₂ output is much, much larger than for petrol or conventional cars,” the expert stated. “All regulatory adjustments regarding PHEVs should be made with utmost caution and in the light of this evidence.”