After a few seconds it is normal. I notice this more when the car is driven park then start again. Does not seem to make the noise when cold, only when hot...sitting and then restarting....Did oil change 0 40 M1 and dealer filter about 1k miles ago and oil level is on the mark.
Sound like when my M5 timing chain guide was coming apart.

 

This is totally normal

if it persists for more than a minute it may need chain tensioner work but the sound comes back

its normal

 

I have this same rattle on startups in the morning on cold start sometimes, or when It's sat for a while and then started. It's concerning but I guess normal...

 

My 1997 Mazda 1.5 5 speed had 280K and was like a mouse.
I change oil once a yr sometime 17-20K on an oil change and never warm it up, start and drive...and never a sound from that motor...sold it and bought a new 2.0 Mazda because of the abuse factor.
6.3 had cam issues, I never experience, but I hate ticking engine noise even for a few seconds. What oil are you all using.
I put in M1 0-40 euro formula from dealer.

 

mine rattles on startup too but almost sounds like its coming from the muffler area, as opposed the the engine rattling others have mentioned.... mine almost sounds like something is flapping in the exhaust and then goes away... annoying but i learned to live with it

 

that Mazda was a simpler engine that doesn't offer what the m157 offers

some things just are what they are. You seem disappointed in your e63 with all the negatives you've found so far... Hope it gets better for you

 

Mine rattles mostly on cold starts and only for between 1-3 seconds

 

The rattle is a worry but if that is normal.....Friends with others E's 2014/2015 2014 ML63 and 2015 S63 no rattle these are cars that I drive parked and then start where my car would rattle at time...not all the time but its a hit or miss...

 

the chain tensioner rattle is very well known to this and the m278 and a few other Benz engines; there is a service bulletin for m157 and m278 engines with excessive rattle and they will fix it and most of the time it just comes back. If it's a worry to you, my advice is to take it to your Benz dealership while it is under warranty and have them assess it so it is documented, and then if it becomes a major problem it will have been documented and they can repair it.

can't have it all. It's a trade off and I've learned that the cost of the car doesn't buy perfection. These are man made machines ... Even $200,000 s65's have issues and quirks as do $300k bentleys

like I said I hope you have a better experience or find something nicer to trade into

 

mine rattles when driving in the 30mph range when the engine is cold...is the chain tensioner rattle only an issue when starting the car?

 

yes, but you may have an issues with tensioner that is covered by this tsb

 

How about it rattling when wet> Drive through a pool of water when its raining and it sounds like an exhaust leak/blow off valve rattle