From the drivers (or possibly passenger) side A pillar/wheel arch/door shut area on speeds exceeding ~40mph?
Well, Since I bought my car back in August 2010, it's had an annoying flappy/rattly sound coming from that area that was definately speed related and definately something to do with the wind catching something.
I put the car into BMW where they recognised the noise, stripped the scuttle panel area, done numerous test drives and could not find what the problem was, I was SURE it was coming from the wheel arch area and even made them remove the inner liner to inspect but they came back with nothing, well no that's a lie the problem seemed to dissappear when they worked on it and it was fine 'til I hit 100mph+ on my own test track
So, i've lived with it since but it's always done my breasticles in, until the other day my friend who works at BMW txt me to tell me the fault is recognised and is on the internal computer (PuMA) and that the problem was actually a nut for securing the wing.....
BMW's measure: "Open the door, apply loctite 454 instant adhesive between the sliding element and the forward end of the side wall near the A pillar
The adhesive should be applied from the outside with the door half open, removal of the front door can therefore be avoided"
Not sure exactly what part it is, but once I find out i'll update with pics, just thought i'd let you's know incase you have the same issue as me!