The new WLTP method, which measures the fuel consumption of cars, is more truthful than the old NEDC method. Nevertheless, the differences between the stated consumption and the actual consumption are still large, especially with plug-in hybrids, which start their WLTP test with a full battery.
Owners do not use their car as intended
And that seems to be exactly the problem in practice, according to German researchers from the Fraunhofer Institute for Systems and Innovation Research (ISI). They analyzed information from more than 100,000 plug-in hybrids from Canada, China, Germany, the Netherlands, Norway and the US. And guess what? Owners do not use the cars as intended.
Plug-in hybrids are four times dirtier in practice
In practice, plug-in hybrids emit between 50 and 300 grams of CO2 per kilometer, according to research. And that is up to four times more than the emissions during laboratory tests (both NEDC and WLTP). The problem is twofold: plug-in owners drive more than is generally assumed (the electric range is therefore not sufficient) and they do not charge their car often enough.
Most PHEV riders only use hybrid mode
In theory, plug-in hybrids should be able to travel the first fifty kilometers electrically, for example, but there are hardly any people who use them like that. Most drivers always have their car in hybrid mode, with the fuel engine regularly assisting or even taking over.
Many people never charge their plug-in hybrid during the day
According to the researchers, PHEV drivers almost never charge their car during a working day or during other daily worries. They propose to encourage drivers to use their plug-in hybrids better: to charge them more often and to drive them more on their own.