Owned this car for almost a year now. It is my fifth BMW and first M car. Other BMWs had no reliability problems and fairly good performance. This car is all performance and no reliability. First 2000 miles in the break-in period, it consumed a quart of engine oil every 100 miles. It seemed like it ran on engine oil and not gasoline. I had problems with transmission (SMG), tire allignment, and driver's window. But I don't know if any other car can match this car's performance, practicality and fun to drive. It is stealthy enough to not attract too much attention, and yet it is powerful enough to street race a Porsche non turbo. Love this car, will buy again when the new model comes out.
SMG is slow but fun and effective. Looks are great, acceleration is awesome, razorblade like handling, 5 seat, four door practicality, nice enough trunk space for at least two golf bags (more may fit but haven't tried). The iDrive has improved since my past 5-series.
Fuel economy is terrible, computer reads 10 mpg average in 70% city, 30% hwy driving. Every part in this car costs double compared to regular 5 series, even the horn costs extra. Reliability is probably comparable to Ferraris and Lambos. Never get in a fenderbender because it will cost a fortune.