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Plug-in hybrid cars release almost five times greater planet-heating emissions than official figures show, as per a recent analysis.

Growing Gap Between Lab and Real-World CO2 Output

Statistics reveals that PHEVs release just 19% less CO₂ than conventional gas and diesel cars, according to research carried out by a non-profit group. That differs significantly with laboratory estimates, which suggested a three-quarters decrease in pollution.

Researchers studied data from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from three and a half times in 2021.

“Actual emissions are rising, while lab-reported emissions are decreasing,” stated a lead analyst involved in the report. “That gap is growing and creates a significant problem. Consequently, PHEVs pollute nearly as much as petrol cars.”

Key Factors Driving the Emissions Gap

Researchers linked most of the gap to inflated estimates of the “utility factor” – the percentage of kilometers travelled in battery power relative to total distance. They found that only 27% of driving was completed in electric mode, whereas lab estimates suggested 84%.

Additionally, when operating in EV mode, emission amounts were well above official estimates. That happened because electric motors were insufficiently powerful enough to operate alone, leading to combustion motors using fossil fuels for nearly one-third of the distance covered in EV mode.

Policy and Financial Implications

Based on calculations, the underestimation of PHEV emissions enabled four large automaker companies to escape more than €5bn in fines between 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ targets.

Furthermore, owners of PHEVs could spend about €500 more annually in running costs than is assumed under laboratory tests.

“The bold statements that automakers often promote about their plug-in hybrid cars are clearly far from the mark,” stated a automotive expert. “Consumers are being duped into believing that by purchasing a PHEV, they are helping the environment and cutting costs. In reality, PHEVs are little improved than standard petrol and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Political Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been brought again into political debates as automakers have pressed the EU to weaken CO₂ standards. A planned ban on new internal combustion cars in 2035 has faced heavy pressure from the automotive sector and opposition from EU countries with large automotive industries.

Some senior officials have suggested plug-in hybrids as a potential “compromise” option to include in the legislation.

An independent energy policy expert, who was unaffiliated with the study, described the analysis a “very useful contribution” after years in which parts of the automotive sector argued there was too little data to properly assess real-world emissions.

“These findings show, beyond any doubt, that the difference in lab and actual PHEV fuel consumption and CO₂ output is significantly larger than for petrol or diesel cars,” they stated. “Any regulatory changes regarding PHEVs should be implemented with extreme caution and considering this evidence.”