A strange 'electric golf cart' like whining noise is coming from the engine in my '11 X5 50i. The engine is a Twin-Scroll Turbo 4.4L V8.

Some patterns I've noticed:
-Doesn't happen when the engine is cold
-Doesn't happen until I really push the engine and then it won't stop for the rest of the day, even if I'm driving slow
-Whine is very noticeable after 2k rpm
-Not noticeable at higher speeds because of road and wind noise
-Seems to come from the right side (behind the glove box)
-The whine pitch is dependent on engine speed (rpm), not vehicle speed.
-Happens in neutral as well, so it's not the transmission or drive-train?

Has anybody else had this problem and had it fixed or rejected for service?

I took it in for service and they did hear the whining noise. They said they've never had a complaint about it.

Yesterday they called me and told me they can't diagnose the problem. Today, I emailed them:

I asked them:

Have you found the issue yet?

You might want to check the alternator or the oil pump for the whine. Another BMW owner had the same issue.

They answered:

We put in a tc case/puma case seeing what they want us to do. We think its possible alternator or oil pump (another vehicle in the shop a few months ago had the same issue) I have to wait on there approval/guidance It is there decision

I found out that:
PuMA is BMW's online technical hotline for delaers. The dealer fills out a form for submittal to BMW's technical gurus and then they send back a response outlining what they (BMW) want you (the dealer) to do to fix the car. Sometimes it's "replace such-and-such" and sometimes they ask for more diagnostic info.

TC is "Teile Clearing". It's German for "parts Clearance". It's BMW givintg the dealer approval to replace a part after we submit a PuMA case outlining what we did to determine that the part is the problem. It's something that BMW has in place so that dealers don't go al willy-nilly replacing $1000 Nav units for no reason or just for "tries-eez".

Is this a lengthy process? Should I ask for a loaner car?