Yeah you really gotta want to own a used BMW - and enjoy working on them. If you want a high milage low maintenance car buy a Honda. I think BMW builds their cars to last as long as the lease. Not that it's poor quality but they are very difficult to service. So labor (time) is expensive, Then parts are expensive if you buy from BMW - a $500 brake vacuum pump from BMW costs $200 from the OEM. Then there's the whole thing about having to have proprietary diagnostic tools to do just about anything. But most things are DIYable just time consuming.
And BMW did things like giving free oil changes under warranty but then require a 15,000 mile oil. And claim the tranny fluid is lifetime (which really means until warranty expires). And then everything talks to a computer, even light bulbs, so everything is "special".
Fortunately the DIY community is all over what are common failures and when they happen and what to do to as PM. Valve stem seals are common over 120,000 miles and an expensive or difficult DIY job however switching to a lower temp thermostat and using a product from liqui-moly called motor saver seems to mitigate the problem if you do it soon enough. Oil burning is a common complaint but again using liqui-molly's Ceratec cleans that up pretty fast. You have to use a high grade, good detergent, premium gas like Shell or Chevron. Or put Techron in before each oil change to clean injectors. You have to do regular fluid flushes but if your idea of fun on a Saturday is working on the car then you've got plenty to do.
Why do it? Driving my M-sport is almost as good as sex. I had a Lexus, Infiniti and a 300ZX and this is better than the best of all three. 0-60 in 4.7 secs is crazy in a 4-door sedan. High end torque so I can mash the pedal from 70-90 in a split second. Four driving modes: Economy (LOL I get 15MPG), Sport (stiffens suspension, changes shift points), Sport Automatic (even more aggressive shift points), and Manual (bat **** crazy). The cool thing about Manual mode is that it down shifts for you. Maybe they all do that now but my Infiniti didn't.
As far as handling it blew me away. It straightens out clover leafs. Zero sway or lean thanks to the DSC that actually adjusts suspension not just brakes like other so called systems. I don't know what speed it would take to get it lose and I'm afraid to find out. Low profile 275's on the rear and 245's on the front. Adaptive steering that adjusts steering angle based on speed, accelerometer input etc. so no drifting LOL. Adaptive headlights (Hudson was ahead of his time). The frickin side bolsters even inflate in turns to hold you in place.
I'll do some mods in the future. I've already done some cosmetic things. I'l add a quad exhaust with a cutout so I can hear the V8. It has a nice low rumble now but it's so damn quiet in the car that you can't hear it.
Bottom line is don't buy a used BMW unless your hobby is working on it. And it helps to have access to a 2nd car ;)