Volkswacht Bodensee - Study shows plug-in hybrids polluting far more than expected

The study by the International Council on Clean Transportation (ICCT), a lobbying group, looked at data from the onboard monitors of roughly 920,000 plug-in hybrids registered between 2021 and 2023.

It found a "substantial and fast-growing gap between real-world and type-approval CO2 emissions for PHEVs registered in 2021–2023".

The type-approval norms include an assumption by regulators about the pollution the vehicles would emit based on the distances they would be driving using the battery and the distances using internal combustion engines.

But the study found that average CO2 emissions in real-world driving were 3.5 times higher than the 2021 type-approval values, and 4.6 times higher than the 2023 type-approval values.

The growing difference was due to an assumption that bigger batteries would lead to increased driving on battery power, but the real-world use data did not bear this out.

The divergence "misleads consumers about expected energy costs" with plug-in hybrids, the ICCT said, as well as unduly opening them up to incentive schemes and skewing the determination whether automakers are complying with emissions rules.

The ICCT, which was behind the 2015 revelations about diesel emissions that became known as the "Dieselgate" scandal, urged the EU to not delay a planned 2027 update to the calculations that would reduce the discrepancy with real-world emissions.

It also called on the EU to use real-world data to guide further updates.

The publication of the study comes as certain automakers, particularly German carmakers, want to see plug-in hybrids continue to be included in the EU's strategy to decarbonise the auto sector.

Pushed by Germany, the EU last December abandoned its plans to ban the registration of new internal combustion engine vehicles in 2035.

Instead, carmakers are supposed to reduce CO2 levels by 90 percent from 2021 levels and compensate the remaining 10 percent.

However, Germany and its allies want the rules loosened further to give more place to hybrid vehicles, according to press reports.

A.Ammann--VB