The gap between official and real CO₂ emissions from plug-in hybrids continues to grow

Berlin. The gap between the official and actual CO₂ emissions of plug-in hybrids is growing. According to an analysis of new EU data by the environmental organization Transport & Environment (T&E), the real emissions from vehicles registered for the first time in 2024 averaged 145 grams of CO2 per kilometer. In the official WLTP measurement it was only 24 grams. A year earlier, 138 grams in practice compared to 28 grams in the test.

This means that standard and practical values ​​have recently developed in opposite directions: from 2023 to 2024, the official information on greenhouse gas emissions fell by around 15 percent, while real emissions increased by five percent. The difference between the two values ​​grew from 110 to 121 grams per kilometer within a year.

The deviation will also increase in the longer term. According to previous T&E evaluations, the real emissions of plug-in hybrids approved in 2021 were around 3.5 times the official value, in 2022 they were four times and in 2023 they were almost five times. For the 2024 vehicles, the factor is now around six. The development has continued uninterrupted since the EU practical measurements began in 2021.

The current evaluation is based on data from around 220,000 plug-in hybrids. Since 2021, new cars have had so-called on-board fuel consumption monitoring devices (OBFCM), which, among other things, record the actual fuel or energy consumption and the distance traveled. The data will be transmitted to the EU and is intended to show how much the values ​​in normal operation deviate from the results of the WLTP test procedure.

A key reason for the deviation is the so-called utility factor, which is taken into account in the manufacturer's information. It describes what proportion of the mileage of a plug-in hybrid is assumed to be electric when calculating the official CO2 value. In everyday life, this proportion is lower than assumed in the previous procedure. The EU has therefore decided on a gradual correction. A further adjustment is planned for 2027, but some car manufacturers and associations want to prevent this.

Plug-in hybrids have an internal combustion engine and at least one electric motor. Unlike normal hybrids, their battery can be charged externally. Ideally, in everyday life - for example when commuting or shopping - they are moved purely electrically; the combustion engine should switch on for long journeys.

In practice, however, many PHEV models are hardly charged - on the one hand, the electric range is short, especially in winter, and on the other hand, charging often takes a very long time. Most recently, German and Chinese manufacturers in particular brought models with larger batteries and significantly higher electric ranges of over 100 kilometers onto the market. It remains to be seen whether this will change user habits and improve CO₂ statistics in the coming years.