Its not much different than owning a mercedes of similar models.
The problems arise when the owner "tries to maintain it with used/worn parts and ustadee" - e.g. If the mechanic does not pay attention to the angle of the suspension when retightening the bolts - It may look OK - but soon the owner will experience a similar repair in 10% of the original life. If the owner does not pay attention to the gauges and overheats the engine - most BMW engines had a water pump design fault.
no doubt BMWs of any model/series are meant to be driven - they are a joy to drive but all that comes at a price - if you buy it dont expect it to repair it to 100% service specification with suzuki mehran approach.
Repairing german cars is not that difficult - it just requires a different approach as good sense and engineering go into it. Similarly you should not expect cheap chinese parts to work in place of genuine good quality parts.