Experience Prius Plug In Battery

Hello together, someone here already has experience with the Prius Plug In?, I have now for three almost three months and am actually quite satisfied with it, my consumption is depending on the reloading possibility at 0.8 to 3.9 ltr. what I find absolutely ok, but what I do not really like is the Accu, which I have never been able to charge so fully that I could tell the ad that it is enough for 25km. At first it was times 22,8km but that is now becoming increasingly less, at the moment it is just 20,3km where the display after several hours of loading shows, I also have the feeling that the Accu gets empty faster and also charges itself less when rolling off the mountain, it was at the beginning still almost 3km where he has charged down my house mountain so now it is not 2km anymore, has the problem already someone with a Prius Plug In?, in my workshop they also do not know any advice, a mechanic meant it could be at the outside temperature, the best would be around 20°C, and that we have now approx.