I've got a 2007 S with auto that I bought new. After almost 7 years of ownership, here's where I stand on the car and BMW as a company:
The car hasn't been too bad for reliability, but I've been lucky. The only significant breakdown I've had was the plastic thermostat housing cracking at 60k. It cost me about $100 in parts and several hours to replace-- it would have been around $500 at the dealer to fix.
It has had some trouble with poor idle and hesitation that has mostly been fixed by doing a Seafoam treatment. This is a result of the direct injection which also plagues the larger BMW's.
Since new, it has had a timing chain rattle, especially when cold. Since I live near the Gulf coast and have always garaged the car, it has never been severe enough to spend the $1000 or so MINI would have charged me to actually fix the problem. This has been a major problem with the R56 and forums are full of folks that have had subsequent catastrophic failures with this item and huge expenses.
Now here's why I'll never buy another BMW, as much as I think their cars are "best in category" in many instances:
Any problems they've had with bad design and shoddy construction they've completely denied and, worse, have blamed them on the customer.
For example, I was told problems I was having with the high pressure fuel pump was because of the gas I was buying. BMW owners were told the same thing. Finally, after years of problems, BMW admitted that there was a problem and recalled the BMW's and replaced the fuel pumps. Except for MINIs, where they just warranted them for longer.
Another example is the timing chain issue. When I complained about the rattle, and I know I was one of thousands, I was told it was because I didn't keep enough oil in the car, which was a load of crap. SEVEN YEARS and after MINI owners spent thousands fixing the problem themselves, BMW finally tacitly admitted the failures and issued a recall. I just had mine done.
The water pump was another recall item, though I didn't have a problem with it and didn't really follow this issue. The thermostat housing is an ongoing issue and fails regularly, but MINI has not done a recall on it. It is stupid design, essentially a complex plastic part (I've heard it called a Jarvik because it looks like the artificial heart) consisting of two halves bonded together and bolted to the side of the engine. Of course, with all those heat cycles and all the bends and flanges and bonding, it eventually cracks. Appparently between 30k and 60k miles, typically. The replacement ones will likely fail in the same time period because, AFAIK, BMW has not redesigned it.
My wife recently fell in love with a BMW 535i. A 2010 with 14k miles for about $32k. I don't often tell her no when she really wants something, but this time no was the answer. I refuse to buy another car from a company that only stands behind its product when forced into a corner. And meanwhile tells the customer that its design flaws are the customer's fault.
Despite the few problems I've personally had, I really like the car. It is great fun to drive and is the most tossable street car I've ever owned. At this point, I think the weaknesses have been addressed and I wouldn't hesitate selling it to a friend. As a matter of fact, a friend has expressed interest in it as a car for his son and I would sell it to him in a minute, though I would certainly detail its history.
So no, I wouldn't buy another new one and I certainly wouldn't buy one with a newly designed drivetrain. If history is any indicator, you'll only be sorting out the design and construction issues for BMW and they won't appreciate the help.
