Just wondering if someone else had this too and what I could do about it.

The most relevant example I can give is:
(All speeds mentioned are in 6th gear) (note: it's a 3000cc engine)
When driving 110 km/h (about 1600rpm) I don't hear the engine running.
At 120 km/h (about 1750rpm) I hear the engine. It's not rattling or so but just the engine noise.
At 130 km/h (about 1900rpm) the engine noise if gone again.

The noise starts at about 1650rpm, peaks at 1750rpm and stops at about 1850rpm. Outside that range all is OK. In other gears I hear it too but it's most relevant in 6th on the highway (speed limit is 120km/h). Solution: I drive 140 km/h but sometimes that's very costly :whistle:

I went to the dealer already but they don't know what to look for. I would describe it as a resonance.

Also I wonder what the normal rpm value is for a 525D LCI 2008 (3000cc) car. In the demo car (same model) I'm pretty sure that 130 km/h had 1600rpm but my car has 1900rpm.

Any ideas?

It probably is resonance! Probably intrinsic to the engine and may even be slightly specific to your build...

I have the same noise in 6th gear and in the same rpm range as you describe. The sound is quite high and a bit irritating. I have not been back to the dealer though. I guess that the 530d may not have this sound and it could possibly be removed by a remap.

Anyone else who experiences this noise, do you have an idea where the noise comes from? Thanks

I have this too, although it isn't loud enough to disturb a conversation or need the volume turning up. Kind of a low growl really.

I remember another forum discussing this, they noticed the turbo vane actuator moving at about this rev range during tests. It did seem to just be a 'problem' on the 525d. I have just gotten used to really, as it doesn't bother me.

Naturally at 70mph in the UK, we are just below 120km/h - so the issue should never arise in the cruise over here... ;)

According to the opening post, 70mph is in the peak point of the rev range. I've yet to experience this as I've not yet purchased the 525d. I don't think it is that bad as I didn't notice it on either of my two test drives. Even if I can hear it, I'm sure it's something I will get used to. I'll have to see what happens.

I have to admit, I didn't notice it until I read about it. I went for a spin and held the revs around the various points, I could then make out the noise.

Seriously, you get more noise from some UK road surfaces at times. It does seem to be some kind of resonance, it's a bit like when the DPF regenerates - so it may be related to that somehow?

Thanks for confirming. Does seem like the kind of thing that is so subtle that it may go unnoticed or people will get used to very quickly. I'm much less concerned about this now.