This is not the best forum to ask your question as most here are "rabid" fans of the car. And to a rabid fan, what's throwing many thousands of dollars on a well designed car with prestige and excellent driving ability. Anything that can go wrong on the Bimmer you are contemplating can and will go wrong, even on the Japanese miracle cars. Every car, if kept going long enough (not the garaged cars of collectors) will go through a standard list of parts that are very predicable.
If you are like me and have to learn many of life's lessons the hard way, you'll realize that if you flush your rad every two years, you probably won't have a head gasket problem. If you flush your auto tranny every three years, the trans will last a long time.
The question for you is this: is the car meaningful enough in your life to be worth throwing a lot of money at it? For example, if you throw $10,000 at the car, you'll have a brand new looking car outside and inside, with many engine components replaced and new tires; is it worth it to you? At resale time, you probably won't get all the money you put into the car.
If you buy Japanese, you'll have the same concerns. I owned a 92 Mazda Protégé, which I really drove long and hard. In the end, I had to replace everything except the engine and the tranny. Some items were replaced a couple of times, like the rad.
You will have problems with any older car you purchase, until all the items that "wear" are replaced.