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PHEVs release nearly 5x greater planet-heating pollution than lab-reported figures show, as per a new analysis.

Widening Gap In Lab and Real-World CO2 Output

Statistics shows that PHEVs emit just 19% lower CO₂ than conventional gas and diesel cars, based on analysis conducted by a non-profit group. This contrasts significantly with lab estimates, which suggested a three-quarters reduction in emissions.

Analysts studied data from onboard fuel consumption monitors of 800,000 vehicles sold in Europe from 2021 and 2023. The team found that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, increased from three and a half times in 2021.

“Actual emissions are increasing, while official emissions are decreasing,” said a senior researcher participating in the report. “This gap is growing and poses a significant issue. Consequently, PHEVs emit nearly as heavily as petrol vehicles.”

Primary Factors Behind the Discrepancy

Researchers linked most of the difference to inflated estimates of the “electric driving share” – the percentage of miles driven in battery mode relative to overall distance. The team determined that just a quarter of travel was done in electric mode, whereas official estimates assumed 84%.

Even, when operating in EV mode, pollution amounts were well above official estimates. That happened because electric motors were insufficiently powerful sufficient to operate independently, leading to combustion motors using gasoline for almost a third of the travel completed in electric mode.

Regulatory and Financial Consequences

According to calculations, the lowballing of PHEV CO2 output enabled several large automaker groups to escape over €5bn in fines between 2021 and 2023, by falsely easing adherence with European Union fleet-average CO₂ targets.

Furthermore, drivers of PHEVs could spend about €500 more annually in running costs than would be estimated under lab tests.

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the mark,” stated a transport analyst. “Buyers are being misled into thinking that by buying a PHEV, they are helping the environment and cutting money. In reality, PHEVs are only slightly better than standard gas and diesel vehicles in terms of energy consumption, CO₂ emissions, and operating expenses.”

Policy Discussion and Industry Pressure

Hybrid vehicles have recently been drawn again into policy discussions as carmakers have pressed the European Union to weaken CO₂ targets. A proposed ban on sales of new internal combustion cars in 2035 has faced heavy pressure from the car sector and opposition from member states with large car industries.

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

One external energy economics expert, who was not involved with the research, described the analysis a “very useful contribution” after years in which parts of the car industry claimed there was too little data to properly evaluate real-world emissions.

“These findings show, without question, that the gap between official and actual PHEV energy use and CO₂ emissions is significantly greater than for petrol or diesel cars,” the expert stated. “Any policy adjustments concerning PHEVs should be made with utmost care and in the light of that data.”