Plug-in Hybrid Vehicles Emit Nearly as Heavily as Gasoline Cars, Study Finds

PHEVs emit almost 5x greater planet-heating emissions than lab-reported figures show, as per a new report.

Growing Discrepancy Between Lab and Actual Emissions

Statistics reveals that PHEVs release only one-fifth less CO₂ than traditional petrol and diesel vehicles, according to research carried out by a advocacy group. This differs sharply with laboratory estimates, which suggested a three-quarters reduction in pollution.

Researchers examined information from in-vehicle fuel consumption monitors of eight hundred thousand cars registered in the EU from 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times greater than lab estimates, up from 3.5 times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” said a senior researcher involved in the report. “That discrepancy is growing and creates a significant issue. As a result, PHEVs emit almost as much as petrol vehicles.”

Key Factors Driving the Emissions Gap

Researchers linked most of the difference to inflated estimates of the “electric driving share” – the ratio of kilometers driven in electric mode relative to overall mileage. They found that only 27% of driving was done in electric mode, whereas lab estimates assumed over four-fifths.

Additionally, when running in EV mode, pollution amounts were well above official projections. This happened because electric motors were insufficiently powerful enough to operate independently, leading to combustion motors using gasoline for almost a third of the travel completed in EV mode.

Regulatory and Financial Implications

According to estimates, the underestimation of PHEV CO2 output allowed several major carmaker companies to escape over €5bn in penalties from 2021 and 2023, by falsely simplifying adherence with EU fleet-average CO₂ targets.

Furthermore, owners of PHEVs would pay about €500 extra annually in running costs than is assumed under lab conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid vehicles are obviously way off the truth,” commented a automotive analyst. “Buyers are being duped into believing that by buying a PHEV, they are benefiting the environment and cutting costs. Actually, PHEVs are little better than regular gas and diesel cars in terms of energy consumption, CO₂ emissions, and running expenses.”

Political Discussion and Industry Lobbying

Hybrid vehicles have recently been brought back into policy debates as automakers have lobbied the European Union to weaken CO₂ targets. A proposed ban on new combustion engine vehicles in 2035 has faced intense lobbying from the car industry and resistance from EU countries with large car industries.

Several senior officials have suggested PHEVs as a potential “flexibility” solution to introduce in the legislation.

One independent energy policy specialist, who was unaffiliated with the study, called the analysis a “very useful contribution” after a long period in which parts of the car sector claimed there was too little information to properly assess actual emissions.

“The results demonstrate, without question, that the gap between lab and real-world PHEV fuel consumption and CO₂ output is much, much greater than for gasoline or conventional cars,” the expert stated. “Any regulatory changes regarding PHEVs should be implemented with utmost caution and in the light of this evidence.”