Plug in Hybrid electric Vehicles Emit Nearly as Much as Petrol Vehicles, Study Finds

Plug-in hybrid cars produce almost 5x greater planet-heating pollution than official data show, as per a new analysis.

Growing Discrepancy In Official and Real-World Emissions

Statistics shows that PHEVs emit just one-fifth less CO₂ than traditional petrol and diesel cars, according to analysis carried out by a advocacy organization. That contrasts significantly with lab estimates, which assumed a 75% decrease in pollution.

Analysts examined data from in-vehicle energy use meters of eight hundred thousand cars sold in Europe from 2021 and 2023. They found that actual CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab figures, up from 3.5 times in 2021.

“Real-world emissions are rising, while lab-reported emissions are decreasing,” stated a lead researcher involved in the report. “This discrepancy is widening and poses a significant problem. Consequently, PHEVs emit nearly as heavily as gasoline vehicles.”

Key Reasons Driving the Emissions Gap

Researchers linked most of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in electric mode compared to overall mileage. They found that only 27% of travel was completed in electric mode, whereas official estimates assumed 84%.

Even, when operating in EV mode, pollution amounts were significantly higher than official estimates. That occurred because electric motors were not strong enough to function alone, leading to engines using gasoline for almost a third of the distance covered in electric mode.

Policy and Economic Implications

According to estimates, the underestimation of PHEV CO2 output enabled four major carmaker groups to avoid more than €5bn in fines from 2021 and 2023, by artificially easing adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs would spend approximately €500 extra per year in running expenses than would be assumed under laboratory tests.

“The strong claims that manufacturers often promote about their plug-in hybrid cars are clearly far from the mark,” commented a transport expert. “Buyers are being misled into thinking that by purchasing a PHEV, they are helping the environment and saving money. Actually, PHEVs are little better than standard gas and diesel cars in terms of fuel use, CO₂ production, and running expenses.”

Political Debate and Automotive Pressure

Hybrid cars have recently been brought back into policy discussions as automakers have lobbied the EU to relax CO₂ standards. A proposed prohibition on sales of new internal combustion vehicles in 2035 has faced intense pressure from the automotive industry and resistance from EU countries with significant car industries.

Several high-level officials have proposed plug-in hybrids as a possible “compromise” solution to introduce in the regulation.

An external energy policy expert, who was unaffiliated with the research, described the analysis a “highly valuable addition” after a long period in which parts of the automotive industry argued there was insufficient data to properly assess real-world emissions.

“These findings show, without question, that the gap in official and actual PHEV fuel consumption and CO₂ emissions is significantly greater than for petrol or diesel cars,” they said. “Any regulatory changes regarding PHEVs should be made with utmost caution and in the light of that evidence.”