Plug in Hybrid Cars Pollute Almost as Heavily as Petrol Cars, Study Finds

PHEVs release nearly five times more planet-heating pollution than official figures show, according to a recent analysis.

Widening Discrepancy In Official and Real-World CO2 Output

Statistics reveals that PHEVs emit just 19% less CO₂ than conventional gas and diesel vehicles, based on research conducted by a non-profit group. This differs significantly with laboratory estimates, which assumed a three-quarters reduction in emissions.

Analysts examined information from onboard fuel consumption monitors of eight hundred thousand cars sold in the EU between 2021 and 2023. They discovered that actual CO₂ output from PHEVs in 2023 were 4.9 times greater than official estimates, increased from 3.5 times in 2021.

“Actual CO2 output are rising, while lab-reported figures are decreasing,” said a senior researcher participating in the study. “This discrepancy is growing and poses a significant issue. As a result, PHEVs pollute almost as much as petrol cars.”

Primary Factors Behind the Discrepancy

Researchers attributed most of the difference to inflated estimates of the “utility factor” – the percentage of miles travelled in battery power compared to total distance. They determined that just a quarter of travel was completed in electric mode, whereas lab estimates assumed over four-fifths.

Even, when operating in electric mode, pollution amounts were well above official projections. This happened because EV motors were insufficiently powerful sufficient to operate independently, resulting to engines burning fossil fuels for almost one-third of the travel covered in EV mode.

Policy and Financial Implications

According to calculations, the lowballing of PHEV CO2 output allowed four large automaker companies to escape over €5bn in fines from 2021 and 2023, by artificially simplifying adherence with EU average fleet CO₂ standards.

Furthermore, drivers of PHEVs could pay about €500 more annually in running costs than would be assumed under lab tests.

“The bold claims that manufacturers often promote about their plug-in hybrid vehicles are obviously far from the mark,” commented a automotive analyst. “Buyers are being duped into thinking that by buying a PHEV, they are benefiting the planet and saving costs. In reality, PHEVs are only slightly improved than standard gas and diesel vehicles in terms of fuel use, CO₂ emissions, and operating costs.”

Policy Debate and Industry Lobbying

Plug-in hybrid vehicles have recently been drawn back into political debates as automakers have pressed the EU to weaken CO₂ standards. A planned prohibition on new internal combustion vehicles in 2035 has faced intense pressure from the car sector and resistance from EU countries with large car industries.

Several senior officials have suggested plug-in hybrids as a possible “compromise” option to introduce in the legislation.

One independent energy economics expert, who was not involved with the study, called the report a “very useful addition” after a long period in which parts of the automotive sector argued there was insufficient information to accurately assess real-world emissions.

“These findings show, beyond any doubt, that the gap between lab and real-world PHEV energy use and CO₂ output is much, much larger than for gasoline or diesel cars,” the expert said. “All regulatory changes concerning PHEVs should be made with extreme care and in the light of that data.”