335i or F01 730d

Hello together, I had to get an E92 335i before the end of the year (N55 engine). Now my father is also there without a car, since I still live at Hotel Mama at 22 and it will be about 3 years now I also in the question whether it should be a 335i or a 730d f01. Why? – I want my father also to have a lower seat and the car to move as soon as he needs it. That’s why a 7 would be really cool, because I really like the F01, but also a 335i a dream car would be the price range is very close both cars between 20- 23.000€. Which of the cars has a higher maintenance? I earn about 1800€ net + 450€ by the way. (sparted would be about 70% of the purchase price) The reason is simply that I somehow also want my father to drive a regular car if he needs it.