Phaeton purchase is pending, what is to be paid attention?

Hi, I hope a little support from you here! I have been driving my Mercedes W203 sports coupe for 2 years now and am now looking for the more… The Phaeton I liked the introduction very much, and since the prices for the vehicle are now working in the basement, I decided to treat myself to a Phaeton. Therefore I wanted to ask you what to pay attention to, which engine is known to be more vulnerable, what should you pay attention to when buying, maybe there are S I don’t care if I have a V6, V8 or V10, I am a quiet driver with my 6 years, more important it is to me that it should be long-lasting. I have set myself as a maximum limit of 17.000€. I think I can buy up to 150.000€ quietly, of course less kilometers are always better, but what would talk about it if it was a top maintained vehicle?? I hope that I am able to from you can learn a lot, I am anyway someone who likes to make, it won’t take long and my Phaeton will look much more beautiful optically than it is already, be it with beautiful rims, by a foling, or or or thanks for your help, which could protect me from a mispurchase ! ! !