Edit: Adding some numbers from https://www.zeit.de/mobilitaet/2020-09/plug-in-hybrid-studie... (sorry, german)
43% of the private owners use the charging option, 18% of the company owned cars. However, due to tax incentives, 63% of all cars registered per year are company owned cars.
The incentives are that you get a substantial tax break if you register a plug-in (or electric) car - leading to the odd result that 40% of all Porsche Panameras registered are plug-in hybrid cars.
Some environment group argue that lower range PHEV is evil because it's just for cheat but I against. PHEV should cover daily use range (YMMV 30-60km?) but shouldn't need much because they have engine for fallback. Equipping mostly unneeded batteries is definitely bad for environment.
It’s also important to keep in mind that the numbers for electric vehicles often include plug-in hybrids. They’re a neat idea in theory, but in practice, they often serve as a hybrid car and never get plugged in. The gains from those vehicles are somewhat limited, except that they are included in the subsidies for electric cars in Germany.