Ugh, Basil, I feel your pain. I suspect your engine is similar to mine... naturally aspirated inline six?
Being an owner myself, BMW does two things. One is the usual engineering mumbo-jumbo (as an engineer, I relate

). The more infuriating thing is when it is done intentionally.
For example, I had to replace the oil filter housing gasket. Top, driver side, easy-peasy access to three of the four bolts. But the fourth bolt was accessed from
behind!!! Yargh. Mirror, a myriad of flex joints and socket extensions, cell phone camera, my seven-year old's small hands, etc., to get the silly bolt out.
If you replace the battery without "reprogramming", your electrical bits will be wonky. I let my last battery get a bit too low - the car would not start on cold winter mornings. I popped in a new NAPA battery, but my rear defroster no longer worked. (Interestingly enough, in the three years since I replaced the battery, it seems to be regaining strength...)
But, the handling and silky smoothness of the inline six help forget and forgive...