One problem related to loud engine noise has been reported for the 2011 BMW 535. The most recently reported issues are listed below.
I got a 2011 BMW 535i xdrive with only 70000 miles on it, it gave me an error saying drivetrain malfunction. I took it to the dealership to run diagnose on it, they told me its ignition coil which they replace only for me to drive it for two days then the engine start making even louder noise and when I took it back, they said the engine is bad and need to be replaced. They found metal parts in the oil filter. How did they not know about it the first time? was there a recall they didn't do!.