Engine grinding sound?
 

At startup, I hear a quick engine grinding sound. I'm aware of the proper way to start a BMW engine...at the quick 3rd turn of key, the engine basically engages itself. It sounds like what I used to do to my CLK 430 when I'd forget the engine was already running and I'd turn the key and it would grind. Any idea what it could be?

My 2003 did that. Is it mostly in exhaust sound?

Not sure what you mean by "in exhaust sound"...but it's the same sound one would hear if their engine was already running and they turned the key. It just suddenly started happening and makes the grinding sound just about every other time I start her up.

Sounds different. Might need to get that looked at.

Quick question, How long does the sound last?

Just a quick second right before the engine starts...