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Plug-in hybrid cars release nearly five times greater global warming pollution than official figures show, as per a new analysis.

Widening Gap Between Official and Real-World Emissions

Statistics reveals that PHEVs release just 19% lower CO₂ than traditional gas and diesel vehicles, according to research carried out by a advocacy organization. This differs significantly with laboratory estimates, which assumed a 75% reduction in emissions.

Researchers studied data from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. They found 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.

“Real-world emissions are increasing, while lab-reported emissions are decreasing,” said a lead researcher involved in the study. “This gap is growing and poses a serious issue. Consequently, PHEVs pollute nearly as much as gasoline cars.”

Primary Reasons Behind the Emissions Gap

Researchers linked the majority of the gap to inflated estimates of the “electric driving share” – the percentage of kilometers travelled in battery mode relative to total distance. The team found that only 27% of driving was done in EV mode, while lab estimates assumed over four-fifths.

Even, when operating in EV mode, emission levels were well above lab estimates. This occurred because electric motors were not strong enough to operate independently, leading to engines using fossil fuels for nearly one-third of the travel completed in electric mode.

Regulatory and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output enabled several large automaker companies to avoid more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU fleet-average CO₂ standards.

Additionally, drivers of PHEVs could spend approximately €500 more annually in operating expenses than would be estimated under laboratory tests.

“The bold statements that automakers like to make about their plug-in hybrid cars are obviously far from the mark,” commented a automotive expert. “Buyers are being misled into thinking that by buying a PHEV, they are benefiting the planet and cutting costs. Actually, PHEVs are little better than regular gas and diesel cars in terms of energy use, CO₂ production, and operating costs.”

Policy Discussion and Automotive Pressure

Plug-in hybrid cars have lately been brought again into political debates as automakers have lobbied the European Union to relax CO₂ standards. A proposed ban on new internal combustion vehicles in 2035 has faced intense lobbying from the automotive sector and opposition from EU countries with large automotive manufacturing.

Some high-level politicians have proposed plug-in hybrids as a possible “compromise” option to introduce in the regulation.

An independent energy policy specialist, who was not involved with the study, described the analysis a “very useful contribution” after years in which parts of the car sector claimed there was too little information to properly evaluate real-world emissions.

“These findings show, without question, that the gap between lab and actual PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert stated. “All regulatory adjustments concerning PHEVs should be implemented with extreme care and in the light of this data.”