Motor vehicles for long distance up to 20000km

Moin! as you can already see at the forum area, I am currently looking for a car for me. Forward to me: I am a beginner (18), I have had a driver’s license for a year and have so far driven 12000 km with a passat B6 (122 hp). Even if I think this statement is bitterly dangerous, I therefore attribute a touch of driving experience to myself. Since I start a job from summer, which requires me to drive about 800 km (~36000 per year) of motorways per week , I am looking for a suitable car. The previous pass is not suitable for this (1.4 l, petrol) and also not in my possession. The most important point for the car is the driving comfort. I want to be able to drive very unexcitedly constant 150-160 km/h, which is why a car in the compact class was not for me to discuss so far (noise insulation, suspension, seats, etc.) (learns me a better one!). Also because of the driving performance I tend to a diesel i Since I also want to drive the car six years on the level, the loss of value will be striking. Therefore, it is all the more important for me to have a car that reliably manages the mileage without major failures: Speak up to 4 years old, preferring to be even younger. I am absolutely open to manufacturers, although German manufacturers have a conscience due to quality and dealer/know-how density. The budget goes up to 20000. For me, things like Xenon are absolutely essential in terms of equipment, and more points would then be added to the manufacturer’s species fish (Aud A4 only with the inside S-Line, otherwise 4-spoke steering wheel). In the case of amateur research, a few models have come into my eye, but what I can’t do is to compare and assess experiences. My favourites so far: Mercedes C 200 ( W 204) Mercedes CLA 200 (Not less than 20000 for this the comfort and noise level should be unbeatable) Thank you for constructive comments!