First car to comfy commuting up to 15,000€ searched

Hello together, I’m just about to buy my first car and came across your forum. Unfortunately, I couldn’t find a really suitable and up-to-date topic, so I’m just going to open up a new one. The default is a day of use for daily commute of 150km mainly on the highway. That’s good over 30,000km a year and so I had thought of a diesel. A gas conversion would also have been possible, but fell due to the reduced range, the lück What is important to me is that the car is very comfortable for my body size (1,95m), is quiet in the interior, has as little fuel as possible (6th gear), has automatic air conditioning. Less important but still very pleasant would be a cruise control and a hands-free device. So far I had thought of a Golf IV 2.0 TDI (because of the 6th gear). However, since I have no idea of cars tenednally I wanted to ask you if you could recommend other cars. Another question would be, which mileage is still safe for such a vehicle (< or > 100,000km?). I hope you can give me another look at my project. VG and thank you very much, Pyro