Chic diesel for highway 30,000 KM a year

Hello, I drive about 30,000 km (soldier) in the year, 90% of them are motorways. I am generally not such a racer and usually drive so 160 km/h, so that the consumption is kept within limits. Since my old car does quite a lot of problems, I could not really spare something so far. I mostly travel alone, sometimes I take 1-2 people with me, therefore the trunk should not be too tiny. There should fit already 3-4 travel bags in. The main focus is here however na The car should not be undermotorized either, i.e. 150hp. What question has been asked me recently, what kind of car should I take? Young used car with warranty but probably very expensive service etc. or a vehicle without and on good luck? I want to commute safely back and forth, little consumption, reliable and chic. Without having to worry about me constantly. Or is that utopian? Greetings