2008 BMW 5 Series 535i 4dr Sedan (3.0L 6cyl Turbo 6M)
This was my first BMW and I was really excited about buying it.
It worked fine for about 6 months and then the trouble started.
First it was the "reduced engine power" message related to the turbo system.
The result of multiple trips to the dealer consisted of: engine reprogramming, replacing the high pressure fuel pump, replacing injectors, replacing a fuel pressure sensor, and reconnecting a vacuum hose that the mechanic "forgot" to connect. The car has had three water pumps installed. I've also had the battery replaced two years after I bought the car (new), the auxiliary jack replaced (it only played through one channel when I got the car.
And a couple of other minor items.
It's also quick and fast, when it runs properly.
BMW solved the problem by discontinuing the engine that can in the 2008 model and a couple of years before and after. Anyone considering this car, do yourself a favor and pass on it.
The turbo/engine problem is fairly common. You can read about it on BMW owner's forums and boards.