I have a buzzing noise that appears at 1800-1900 rpm upon acceleration. It appears at the save rpm through all gears. Any ideas?

Killer bees?

Try checking to see how well the plastic panel below the steering wheel/instrument cluster is mounted. Mine started buzzing a bit once things started getting cold down here in Virginia.

I also had a much loader and persistent buzzing from the roof (Z4 coupe) that was only resolved when the dealer took the roof panels off. Much to my relief (because you wonder that maybe you are the only one that can discern the noise) it became obvious that the wiring lines through the roof had not been attached to their respective clips. So much for American build quality.

Much to my annoyance, my girlfriend usually insists that the stray noise I hear are only in my imagination. Good luck tracking the sound down.