Maybe now with gas above 2€/liter, we'll see more people charging their PHEVs. However they are also a rich person's toy, since you need to charge them at home to have the battery-powered miles be cheaper than the petrol-powered ones ergo you need a home with a garage.

At public chargers you pay much more than at home per kWh. On top of that, they have been incentivized (0,25 Regelung) for companies as fleet cars (Dienstwagen) and companies give out free petrol so you have no incentive to charge it at home using your own electricity when you can just fill up otherwise with free petrol.