Budget interior tips and ideas

I painted my door panels black (from brown), painted the rear seat with black leather paint.
Used regular black paint on the roofliner, applied with a roller.

Front (BMW) seats were already black. I used black nylon carpet, sliced in 3 parts (front left & right and in front of the rearseat).
Mounted a console between the front seats that covers up the splitseam in the carpet nicely.