Question of financing: sensible, or too much?

Hello in the round, I have a financing question. My old car will call for some repairs to the next TÜV (>1000 €) and is a small car, gasoline, 9 years old. I drive more than 50km of highway and city a day + excursions on weekends, more than 12 thousand a year. After 3 1/2 years I would like to have something more comfortable now. At the moment I could probably get rid of it between 2500 and 3500 euros. Desired vehicle is currently a 1 BMW, Diesel, 116d, from 2016, 43 tsd. km, from the Händl I would pay 4000 – 4500 €. The car costs 13500 €. 9000/9500 € would be to be financed. I would be able to pay a monthly rate of 161 € if I were to finance more than 60 months. Basically, this is acceptable to me, as I expect an additional salary increase of (net) 200 € in the summer and I have an indefinite job in the ÖD. } Question: Do I plan here with a too long funding period with a view to the age of the vehicle? The second point that concerns me is the maintenance. My car is now rather cheap. However, I do not see the striking differences between Golf, Astra and BMW in a free workshop. The Astra got away with the costs even worse than the 116d according to the ADAC used car check. In other threads I have read a lot about this, but who has a very concrete experience with models from 2015 on, I would be very grateful to ite to share. Greetings!