🔗 Share this article

Plug-in hybrid cars release almost 5x more planet-heating emissions than lab-reported data indicate, according to a new report.

Growing Gap Between Official and Actual Emissions

Data reveals that PHEVs emit just 19% lower CO₂ than conventional petrol and diesel cars, according to research carried out by a advocacy group. This contrasts significantly with laboratory estimates, which assumed a three-quarters reduction in emissions.

Researchers examined data from in-vehicle fuel consumption monitors of 800,000 cars registered in Europe between 2021 and 2023. The team discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than lab figures, up from three and a half times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” stated a lead researcher involved in the study. “This gap is widening and poses a significant problem. As a result, PHEVs emit nearly as heavily as gasoline cars.”

Primary Factors Behind the Emissions Gap

Researchers linked most of the gap to inflated estimates of the “utility factor” – the ratio of kilometers driven in electric power compared to total mileage. They determined that only a quarter of driving was done in electric mode, whereas lab estimates assumed over four-fifths.

Even, when operating in electric mode, emission amounts were significantly higher than lab estimates. This occurred because electric motors were insufficiently powerful enough to function alone, leading to engines using fossil fuels for almost a third of the distance covered in EV mode.

Policy and Economic Consequences

Based on calculations, the underestimation of PHEV emissions enabled four large automaker companies to escape over €5bn in penalties between 2021 and 2023, by falsely easing adherence with European Union average fleet CO₂ targets.

Additionally, drivers of PHEVs could pay approximately €500 more annually in running costs than would be estimated under lab conditions.

“The strong statements that automakers like to make about their PHEV cars are obviously far from the mark,” stated a automotive expert. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little improved than regular petrol and diesel vehicles in terms of energy consumption, CO₂ production, and running expenses.”

Policy Discussion and Industry Pressure

Hybrid vehicles have recently been drawn again into political debates as automakers have pressed the EU to weaken CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced heavy lobbying from the automotive industry and opposition from EU countries with large automotive industries.

Several high-level politicians have suggested PHEVs as a possible “compromise” solution to introduce in the legislation.

An independent energy economics expert, who was unaffiliated with the study, called the report a “highly valuable addition” after years in which segments of the car industry argued there was too little data to properly assess real-world emissions.

“The results show, beyond any doubt, that the difference in official and real-world PHEV fuel consumption and CO₂ emissions is much, much larger than for gasoline or conventional cars,” the expert said. “All regulatory changes concerning PHEVs should be made with extreme caution and in the light of this data.”