Plug in Hybrid Cars Emit Nearly as Much as Gasoline Cars, Study Reveals

Plug-in hybrid cars emit almost five times more global warming emissions than lab-reported figures show, according to a new report.

Widening Discrepancy In Lab and Actual CO2 Output

Statistics reveals that PHEVs release just one-fifth lower CO₂ than conventional petrol and diesel vehicles, according to analysis carried out by a non-profit organization. This differs significantly with lab tests, which assumed a 75% reduction in emissions.

Researchers studied data from in-vehicle fuel consumption monitors of 800,000 cars registered in the EU from 2021 and 2023. They found that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official figures, up from 3.5 times in 2021.

“Real-world CO2 output are rising, while official emissions are falling,” said a lead analyst participating in the report. “This discrepancy is growing and poses a significant problem. Consequently, PHEVs emit nearly as much as gasoline cars.”

Primary Factors Driving the Emissions Gap

Researchers linked most of the difference to overestimates of the “utility factor” – the ratio of kilometers driven in battery power relative to overall distance. The team determined that only a quarter of travel was completed in EV mode, whereas lab estimates suggested over four-fifths.

Even, when operating in electric mode, pollution levels were significantly higher than lab estimates. That occurred because EV motors were not strong enough to operate independently, resulting to combustion motors burning fossil fuels for almost a third of the distance completed in EV mode.

Regulatory and Economic Consequences

Based on estimates, the underestimation of PHEV emissions enabled four major carmaker groups to avoid over €5bn in penalties between 2021 and 2023, by artificially simplifying adherence with European Union average fleet CO₂ standards.

Furthermore, drivers of PHEVs would pay approximately €500 more per year in running costs than would be assumed under laboratory tests.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are clearly way off the mark,” stated a automotive analyst. “Consumers are being misled into thinking that by buying a PHEV, they are benefiting the environment and saving money. In reality, PHEVs are little better than regular petrol and diesel cars in terms of fuel consumption, CO₂ production, and operating expenses.”

Political Discussion and Automotive Lobbying

Plug-in hybrid vehicles have lately been drawn again into policy discussions as carmakers have pressed the EU to weaken CO₂ targets. A proposed ban on new combustion engine vehicles in 2035 has faced intense pressure from the automotive sector and resistance from EU countries with large car manufacturing.

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

One independent energy policy specialist, who was not involved with the study, described the report a “highly valuable addition” after years in which segments of the automotive industry argued there was too little information to properly evaluate real-world CO2 output.

“The results show, beyond any doubt, that the gap in official and real-world PHEV energy use and CO₂ output is significantly greater than for gasoline or diesel vehicles,” the expert stated. “Any regulatory changes concerning PHEVs should be implemented with extreme caution and considering this data.”