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

Plug-in hybrid electric vehicles produce almost five times greater planet-heating pollution than official figures show, as per a recent analysis.

Widening Gap In Lab and Actual CO2 Output

Data reveals that PHEVs emit only one-fifth less CO₂ than conventional gas and diesel vehicles, according to analysis carried out by a advocacy organization. That differs significantly with lab tests, which suggested a three-quarters reduction in pollution.

Researchers studied data from in-vehicle energy use meters of 800,000 vehicles sold in Europe between 2021 and 2023. The team found that real-world CO₂ output from PHEVs in 2023 were nearly five times higher than lab figures, up from 3.5 times in 2021.

“Actual CO2 output are increasing, while lab-reported figures are falling,” said a lead analyst participating in the study. “That gap is widening and creates a serious issue. As a result, PHEVs pollute almost as much as petrol cars.”

Primary Factors Driving the Discrepancy

Analysts linked the majority of the difference to overestimates of the “electric driving share” – the percentage of miles driven in electric mode compared to total distance. The team found that only 27% of driving was completed in electric mode, whereas official estimates suggested 84%.

Additionally, when operating in EV mode, pollution amounts were well above lab estimates. That occurred because electric motors were not strong sufficient to operate alone, resulting to engines using gasoline for nearly a third of the distance completed in EV mode.

Regulatory and Economic Implications

Based on estimates, the underestimation of PHEV CO2 output enabled several major automaker groups to avoid more than €5bn in fines between 2021 and 2023, by artificially easing compliance with EU fleet-average CO₂ targets.

Additionally, drivers of PHEVs could pay about €500 more annually in running expenses than is estimated under lab conditions.

“The bold statements that automakers often promote about their plug-in hybrid cars are obviously way off the truth,” stated a transport expert. “Buyers are being misled into believing that by purchasing a PHEV, they are helping the environment and saving costs. Actually, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and operating costs.”

Political Discussion and Automotive Lobbying

Plug-in hybrid cars have lately been brought back into policy discussions as carmakers have lobbied the European Union to relax CO₂ targets. A proposed prohibition on sales of new combustion engine vehicles in 2035 has faced intense pressure from the automotive industry and opposition from member states with large automotive industries.

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

One external energy economics specialist, who was not involved with the research, called the analysis a “highly valuable addition” after a long period in which parts of the car industry claimed there was too little information to accurately evaluate real-world CO2 output.

“The results show, without question, that the gap in official and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or conventional cars,” the expert said. “All regulatory adjustments regarding PHEVs should be implemented with utmost care and considering that evidence.”