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Plug-in hybrid cars release almost five times greater global warming emissions than official data show, as per a new analysis.

Growing Gap Between Lab and Actual CO2 Output

Statistics reveals that PHEVs emit only 19% less CO₂ than conventional petrol and diesel vehicles, according to analysis carried out by a advocacy organization. That contrasts significantly with lab tests, which suggested a three-quarters reduction in emissions.

Researchers studied information from in-vehicle energy use monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times higher than lab estimates, increased from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are falling,” stated a senior analyst participating in the report. “This gap is widening and poses a serious issue. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Researchers linked most of the gap to overestimates of the “utility factor” – the percentage of kilometers travelled in electric power compared to total distance. They determined that only a quarter of driving was done in EV mode, whereas lab estimates assumed 84%.

Even, when running in electric mode, pollution amounts were well above lab estimates. That occurred because EV motors were not strong sufficient to function independently, leading to engines burning fossil fuels for almost a third of the distance covered in electric mode.

Regulatory and Financial Consequences

Based on estimates, the underestimation of PHEV CO2 output enabled four large carmaker companies to avoid over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could spend approximately €500 more annually in running expenses than is assumed under laboratory conditions.

“The strong statements that manufacturers like to make about their plug-in hybrid vehicles are obviously way off the mark,” stated a automotive expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are helping the environment and cutting money. Actually, PHEVs are little improved than standard gas and diesel cars in terms of fuel consumption, CO₂ emissions, and operating costs.”

Policy Discussion and Automotive Lobbying

Hybrid cars have lately been drawn back into policy discussions as carmakers have lobbied the European Union to weaken 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 car industries.

Some senior politicians have proposed PHEVs as a potential “flexibility” solution to introduce in the legislation.

An independent energy policy specialist, who was unaffiliated with the study, described the report a “very useful contribution” after years in which segments of the automotive sector claimed there was too little data to accurately evaluate real-world CO2 output.

“These findings demonstrate, beyond any doubt, that the difference in lab and actual PHEV energy use and CO₂ output is much, much greater than for gasoline or conventional vehicles,” they said. “Any regulatory adjustments concerning PHEVs should be implemented with extreme caution and considering this data.”