Lexus experience tips Audi or Lexus

I have an Audi A4 2.5TDI and so soon a new car should come here… By chance I have come to Lexus Either the IS or the GS now ask my questions: How are these vehicles in general? Processing… Are there often problems with the vehicles? Certain Lexus diseases? (For the A4 e.g. crossbars) Are spare parts expensive or are there also cheap on the Internet (e.g. Audi parts without end and cheap) How much km can one drive with such a Lexus in the rule? By that I mean: My A4 has already 285,000km and it packs loosely some more! What must one pay attention to when buying special at lexus? thank you in advance Momek_ke