Plug-in Hybrid Cars Emit Almost as Heavily as Petrol Vehicles, Study Reveals

Plug-in hybrid electric vehicles produce nearly five times greater planet-heating pollution than official data indicate, according to a recent report.

Widening Discrepancy In Lab and Real-World CO2 Output

Data shows that PHEVs release just 19% less CO₂ than traditional gas and diesel vehicles, based on research conducted by a non-profit organization. That contrasts significantly with laboratory estimates, which suggested a three-quarters decrease in pollution.

Analysts studied information from in-vehicle fuel consumption meters of 800,000 cars registered in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were nearly five times higher than lab figures, increased from 3.5 times in 2021.

“Real-world emissions are rising, while official emissions are decreasing,” stated a senior analyst involved in the report. “That discrepancy is growing and creates a serious problem. As a result, PHEVs pollute almost as much as gasoline cars.”

Primary Factors Behind the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “utility factor” – the percentage of kilometers driven in battery power relative to overall mileage. They found that only a quarter of driving was completed in electric mode, whereas official assumptions suggested 84%.

Even, when operating in EV mode, pollution amounts were significantly higher than official estimates. This occurred because EV motors were insufficiently powerful sufficient to operate independently, leading to combustion motors using gasoline for nearly one-third of the travel completed in EV mode.

Regulatory and Financial Implications

Based on estimates, the underestimation of PHEV CO2 output enabled four large automaker companies to escape more than €5bn in fines from 2021 and 2023, by falsely simplifying adherence with European Union fleet-average CO₂ targets.

Additionally, drivers of PHEVs could spend about €500 more annually in running expenses than would be estimated under laboratory conditions.

“The bold claims that manufacturers often promote about their PHEV vehicles are obviously far from the mark,” stated a transport expert. “Consumers are being misled into thinking that by purchasing a PHEV, they are benefiting the environment and saving costs. In reality, PHEVs are only slightly improved than standard gas and diesel cars in terms of energy consumption, CO₂ production, and running costs.”

Policy Discussion and Industry Pressure

Hybrid vehicles have lately been brought again into policy discussions as carmakers have lobbied the European Union to relax CO₂ targets. A planned ban on new combustion engine vehicles in 2035 has faced intense pressure from the car industry and resistance from EU countries with significant automotive manufacturing.

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

An independent energy economics specialist, who was not involved with the research, described the report a “highly valuable addition” after a long period in which segments of the car industry claimed there was insufficient data to accurately evaluate actual CO2 output.

“These findings show, without question, that the gap between official and real-world PHEV fuel consumption and CO₂ emissions is much, much greater than for gasoline or diesel vehicles,” the expert stated. “Any policy changes concerning PHEVs should be made with utmost caution and in the light of that evidence.”