Plug-in Hybrid electric Cars Emit Almost as Much as Gasoline Vehicles, Report Finds

PHEVs produce almost five times more planet-heating pollution than official data indicate, according to a recent report.

Growing Gap In Lab and Actual CO2 Output

Data reveals that PHEVs emit only 19% lower CO₂ than traditional gas and diesel vehicles, based on analysis conducted by a advocacy group. This contrasts significantly with laboratory tests, which suggested a 75% reduction in emissions.

Analysts studied information from onboard energy use monitors of 800,000 cars registered in the EU between 2021 and 2023. The team discovered that real-world CO₂ output from PHEVs in 2023 were 4.9 times higher than official estimates, increased from three and a half times in 2021.

“Real-world CO2 output are rising, while lab-reported emissions are falling,” said a senior researcher participating in the report. “This gap is growing and creates a serious issue. As a result, PHEVs emit nearly as heavily as petrol vehicles.”

Key Reasons Driving the Emissions Gap

Analysts attributed the majority of the difference to overestimates of the “electric driving share” – the ratio of kilometers driven in electric mode relative to total distance. They found that just 27% of travel was completed in electric mode, whereas lab estimates assumed 84%.

Additionally, when operating in EV mode, pollution amounts were significantly higher than official estimates. That occurred because electric motors were insufficiently powerful enough to operate alone, leading to combustion motors burning fossil fuels for nearly a third of the distance covered in EV mode.

Regulatory and Economic Consequences

According to calculations, the lowballing of PHEV CO2 output enabled several large carmaker companies to avoid over €5bn in fines between 2021 and 2023, by falsely easing compliance with EU average fleet CO₂ targets.

Furthermore, drivers of PHEVs would pay about €500 more per year in operating costs than would be assumed under lab tests.

“The strong statements that manufacturers often promote about their PHEV vehicles are clearly way off the truth,” stated a automotive expert. “Buyers are being misled into believing that by purchasing a PHEV, they are benefiting the planet and cutting costs. In reality, PHEVs are only slightly better than regular petrol and diesel vehicles in terms of fuel use, CO₂ production, and running costs.”

Political Debate and Automotive Lobbying

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

Several senior officials have proposed plug-in hybrids as a possible “flexibility” option to introduce in the regulation.

One external energy economics expert, who was unaffiliated with the study, described the report a “very useful addition” after a long period in which parts of the automotive industry claimed there was insufficient data to properly evaluate real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference in lab and real-world PHEV fuel consumption and CO₂ emissions is significantly larger than for petrol or conventional cars,” the expert said. “Any policy adjustments concerning PHEVs should be implemented with extreme care and considering this data.”