History of problems
personally i like the 8 series.heard the guy that designed it were canned for it but not sure if it is true.12cyl motors are gonna cost more just because they take more of everything and nothing is easy to get to.but depends on how the car is and how it was maintained.ive worked on some that were unroadworthy but ran great and some that looked really clean that always having issues.vent valves,throttles,o2 sensors,headlight issues due to the folding headlights and oil leaks are common.but i can say that about almost all bmws
The 12 cylinder is basically two inline 6's that are mated and many components appear twice - such as the water pump. Having owned a 91 850i, I can attest that it is very expensive to repair these cars. I did miss the car after selling it so bought an 840ci. Electronics are still an issue - most traceable to the General Module in the dash below the steering wheel. Most common complaint is actually outside temperature related: Under 40F, the contacts in the GM don't function properly and one finds that the windows, wipers, courtesy lights and door locks will not work - or they will flash on/off intermittantly.This creates a real problem because the windows seal into the roof - and you won't be able to get in the car. If this starts happening to you best leave one of the windows down about 1 inch during colder whether.