Plug in Hybrid Vehicles Pollute Almost as Much as Gasoline Cars, Study Finds

PHEVs produce almost five times more global warming emissions than official data indicate, according to a new report.

Growing Gap Between Official and Actual Emissions

Data reveals that PHEVs release only 19% less CO₂ than conventional gas and diesel vehicles, based on analysis carried out by a non-profit group. That differs sharply with laboratory estimates, which assumed a 75% reduction in pollution.

Analysts examined data from in-vehicle fuel consumption monitors of eight hundred thousand vehicles sold in Europe from 2021 and 2023. They discovered that real-world CO₂ emissions from PHEVs in 2023 were 4.9 times greater than lab estimates, up from 3.5 times in 2021.

“Actual CO2 output are rising, while official emissions are falling,” said a lead analyst participating in the study. “This gap is widening and creates a significant issue. As a result, PHEVs emit almost as much as gasoline cars.”

Key Factors Driving the Discrepancy

Researchers attributed the majority of the gap to inflated estimates of the “utility factor” – the ratio of kilometers travelled in electric power relative to overall mileage. They found that just a quarter of travel was completed in EV mode, whereas official assumptions suggested over four-fifths.

Even, when operating in electric mode, emission levels were significantly higher than lab estimates. This happened because electric motors were insufficiently powerful enough to function independently, resulting to combustion motors burning gasoline for almost a third of the travel completed in electric mode.

Policy and Financial Consequences

Based on calculations, the lowballing of PHEV CO2 output allowed several large carmaker groups to escape more than €5bn in fines from 2021 and 2023, by falsely easing adherence with EU average fleet CO₂ standards.

Furthermore, owners of PHEVs could spend approximately €500 extra per year in operating costs than is assumed under laboratory conditions.

“The strong statements that manufacturers often promote about their plug-in hybrid cars are clearly way off the truth,” commented a automotive expert. “Buyers are being duped into thinking that by purchasing a PHEV, they are helping the environment and cutting money. In reality, PHEVs are only slightly better than regular gas and diesel cars in terms of energy consumption, CO₂ production, and running expenses.”

Policy Debate and Industry Lobbying

Plug-in hybrid cars have lately been drawn again into political debates as carmakers have lobbied the EU to weaken CO₂ targets. A proposed ban on sales of new combustion engine vehicles in 2035 has faced intense pressure from the automotive industry and resistance from member states with large car industries.

Some high-level politicians have proposed plug-in hybrids as a possible “flexibility” option to introduce in the regulation.

An independent energy economics expert, who was not involved with the study, called the report a “very useful addition” after years in which segments of the car industry claimed there was too little information to properly assess real-world CO2 output.

“The results demonstrate, beyond any doubt, that the difference between official and actual PHEV fuel consumption and CO₂ emissions is much, much greater than for petrol or conventional cars,” the expert said. “All policy changes concerning PHEVs should be implemented with utmost caution and considering that evidence.”